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Anatomy and Physiology of Animals/Urinary System

Objectives
After completing this section, you should know:
 * Understand the parts of the urinary system.
 * The structure and function of a kidney.
 * The structure and function of a kidney tubule or nephron.
 * The processes of filtration, reabsorption, secretion and concentration that convert blood to urine in the kidney tubule.
 * The function of antidiuretic hormone in producing concentrated urine.
 * The composition, storage and voiding of normal urine.
 * Abnormal constituents of urine and their significance.
 * The functions of the kidney in excreting nitrogenous waste, controlling water levels and regulating salt concentrations and acid-base balance.
 * That birds do not have a bladder.

Homeostasis
It is defined as the processes in which the animals or humans regulate their internal temperature. Homeostasis is the maintenance of a stable internal environment. Homeostasis is a term coined in 1959 to describe the physical and chemical parameters that an organism must maintain to allow proper functioning of its component cells, tissues, organs, and organ systems.

Recall that enzymes function best when within a certain range of temperature and pH, and that cells must strive to maintain a balance between having too much or too little water in relation to their external environment. Both situations demonstrate homeostasis. Just as we have a certain temperature range (or comfort zone), so our body has a range of environmental (internal as well as external) parameters within which it works best. Multicellular organisms accomplish this by having organs and organ systems that coordinate their homeostasis. In addition to the other functions that life must perform (recall the discussion in our Introduction chapter), unicellular creatures must accomplish their homeostasis within but a single cell!

Single-celled organisms are surrounded by their external environment. They move materials into and out of the cell by regulation of the cell membrane and its functioning. Most multicellular organisms have most of their cells protected from the external environment, having them surrounded by an aqueous internal environment. This internal environment must be maintained in such a state as to allow maximum efficiency. The ultimate control of homeostasis is done by the nervous system. Often this control is in the form of negative feedback loops. Heat control is a major function of homeostatic conditions that involves the integration of skin, muscular, nervous, and circulatory systems.

The difference between homeostasis as a single cell performs it and what a multicelled creature does derives from their basic organizational plan: a single cell can dump wastes outside the cell and just be done with it. Cells in a multicelled creature, such as a human or cat, also dump wastes outside those cells, but like the trash can or dumpster outside my house/apartment, those wastes must be carted away. The carting away of these wastes is accomplished in my body by the circulatory system in conjunction with the excretory system. For my house, I have the City of Phoenix sanitation department do that (and get to pay each month for their service!).

The ultimate control of homeostasis is accomplished by the nervous system (for rapid responses such as reflexes to avoid picking up a hot pot off the stove) and the endocrine system (for longer-term responses, such as maintaining the body levels of calcium, etc.). Often this homeostatic control takes the form of negative feedback loops. There are two types of biological feedback: positive and negative. Negative feedback turns off the stimulus that caused it in the first place. Your house’s heater (or cooler for those of us in the Sun Belt) acts on the principle of negative feedback. When your house cools off below the temperature set by your thermostat, the heater is turned on to warm air until the temperature is at or above what the thermostat is set at. The thermostat detects this rise in temperature and sends a signal to shut off the heater, allowing the house to cool of until the heater is turned on yet again and the cycle (or loop) continues.

Water In The Body
Water is essential for living things to survive because all the chemical reactions within a body take place in a solution of water. An animal’s body consists of up to 80% water. The exact proportion depends on the type of animal, its age, sex, health and whether or not it has had sufficient to drink. Generally animals do not survive a loss of more than 15% of their body water.

In vertebrates almost 2/3rd of this water is in the cells (intracellular fluid). The rest is outside the cells (extracellular fluid) where it is found in the spaces around the cells (tissue fluid), as well as in the blood and lymph. Water is considered to be the source of life. It is important for animal life because of the following reasons:

(i) Water is vital body fluid which is essential for regulating the processes such as, digestion , transport of nutrients and excretion. Water dissolves ionic and large number of polar organic compounds. Thus, it transports the products of digestion to the place of requirement of the body.

(ii) Water regulates the body temperature by the process of sweating and evaporation.

(iii) Water is a medium for all metabolic reactions in the body. All metabolic reactions in the body take place in solution phase.

(iv) Water provides habitat for various animals in the form of ponds and rivers, sea, etc.

Diagram 12.1 - Water in the body

Maintaining Water Balance
Animals lose water through their skin and lungs, in the faeces and urine. These losses must be made up by water in food and drink and from the water that is a by-product of chemical reactions. If the animal does not manage to compensate for water loss the dissolved substances in the blood may become so concentrated they become lethal. To prevent this happening various mechanisms come into play as soon as the concentration of the blood increases. A part of the brain called the hypothalamus is in charge of these homeostatic processes. The most important is the feeling of thirst that is triggered by an increase in blood concentration. This stimulates an animal to find water and drink it.

The kidneys are also involved in maintaining water balance as various hormones instruct them to produce more concentrated urine and so retain some of the water that would otherwise be lost (see later in this Chapter and Chapter 16).

Desert Animals
Coping with water loss is a particular problem for animals that live in dry conditions. Some, like the camel, have developed great tolerance for dehydration. For example, under some conditions, camels can withstand the loss of one third of their body mass as water. They can also survive wide daily changes in temperature. This means they do not have to use large quantities of water in sweat to cool the body by evaporation.

Smaller animals are more able than large ones to avoid extremes of temperature or dry conditions by resting in sheltered more humid situations during the day and being active only at night.

The kangaroo rat is able to survive without access to any drinking water at all because it does not sweat and produces extremely concentrated urine. Water from its food and from chemical processes is sufficient to supply all its requirements.

Excretion
Animals need to excrete because they take in substances that are excess to the body’s requirements and many of the chemical reactions in the body produce waste products. If these substances were not removed they would poison cells or slow down metabolism. All animals therefore have some means of getting rid of these wastes.

The major waste products in mammals are carbon dioxide that is removed by the lungs, and urea that is produced when excess amino acids (from proteins) are broken down. Urea is filtered from the blood by the kidneys.

Diagram 12.2 - The position of the organs of the urinary system in a dog

BY GIZAW MEKONNEN

The Kidneys And Urinary System
The urinary system, also known as the renal system or urinary tract, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, control levels of electrolytes and metabolites, and regulate blood pH. The urinary tract is the body's drainage system for the eventual removal of urine.[1] The kidneys have an extensive blood supply via the renal arteries which leave the kidneys via the renal vein. Each kidney consists of functional units called nephrons. Following filtration of blood and further processing, wastes (in the form of urine) exit the kidney via the ureters, tubes made of smooth muscle fibres that propel urine towards the urinary bladder, where it is stored and subsequently expelled from the body by urination (voiding). The female and male urinary system are very similar, differing only in the length of the urethra.

Urine is formed in the kidneys through a filtration of blood. The urine is then passed through the ureters to the bladder, where it is stored. During urination, the urine is passed from the bladder through the urethra to the outside of the body.

800–2,000 milliliters (mL) of urine are normally produced every day in a healthy human. This amount varies according to fluid intake and kidney function.

The kidneys in mammals are bean-shaped organs that lie in the abdominal cavity attached to the dorsal wall on either side of the spine (see diagram 12.2). An artery from the dorsal aorta called the renal artery supplies blood to them and the renal vein drains them.

Diagram 12.3 - The urinary system

To the naked eye kidneys seem simple enough organs. They are covered by a fibrous coat or capsule and if cut in half lengthways (longitudinally) two distinct regions can be seen - an inner region or medulla and the outer cortex. A cavity within the kidney called the pelvis collects the urine and carries it to the ureter, which connects with the bladder where the urine is stored temporarily. Rings of muscle (sphincters) control the release of urine from the bladder and the urine leaves the body through the urethra (see diagrams 12.3 and 12.4).

Diagram 12.4 - The dissected kidney

Kidney Tubules Or Nephrons
It is only when you examine kidneys under the microscope that you find that their structure is not simple at all. The cortex and medulla are seen to be composed of masses of tiny tubes. These are called kidney tubules or nephrons (see diagrams 12.5 and 12.6). A human kidney consists of over a million of them.

Diagram 12.5 - Several kidney tubules or nephrons

Diagram 12.6 - A kidney tubule or nephron

At one end of each nephron, in the cortex of the kidney, is a cup shaped structure called the (Bowman’s or renal) capsule. It surrounds a tuft of capillaries called the glomerulus that carries high-pressure blood. Together the glomerulus and capsule act as a blood-filtering device (see diagram 12.7). The holes in the filter allow most of the contents of the blood through except the red and white cells and large protein molecules. The fluid flowing from the capsule into the rest of the kidney tubule is therefore very similar to blood plasma and contains many useful substances like water, glucose, salt and amino acids. It also contains waste products like urea.

Processes Occurring In The Nephron
After entering the glomerulus the filtered fluid flows along a coiled part of the tubule (the proximal convoluted tubule) to a looped portion (the Loop of Henle) and then to the collecting tube via a second length of coiled tube (the distal convoluted tubule) (see diagram 12.6). From the collecting ducts the urine flows into the renal pelvis and enters the ureter.

Note that the glomerulus, capsule and both coiled parts of the tubule are all situated in the cortex of the kidney while the loops of Henle and collecting ducts make up the medulla (see diagram 12.5).

As the fluid flows along the proximal convoluted tubule useful substances like glucose, water, salts, potassium ions, calcium ions and amino acids are reabsorbed into the blood capillaries that form a network around the tubules. Many of these substances are transported by active transport and energy is required.

Diagram 12.7 - Filtration in the glomerulus and capsule

In a separate process, some substances, particularly potassium, ammonium and hydrogen ions, and drugs like penicillin, are actively secreted into the distal convoluted tubule.

By the time the fluid has reached the collecting ducts these processes of absorption and secretion have changed the fluid originally filtered into the Bowman’s capsule into urine. The main function of the collecting ducts is then to remove more water from the urine if necessary. These processes are summarised in diagram 12.8.

Normal urine consists of water, in which waste products such as urea and salts such as sodium chloride are dissolved. Pigments from the breakdown of red blood cells give urine its yellow colour.

The Production Of Concentrated Urine
Because of the high pressure of the blood in the glomerulus and the large size of the pores in the glomerulus/capsule-filtering device, an enormous volume of fluid passes into the kidney tubules. If this fluid were left as it is, the animal’s body would be drained dry in 30 minutes. In fact, as the fluid flows down the tubule, over 90% of the water in it is reabsorbed. The main part of this reabsorption takes place in the collecting tubes.

The amount of water removed from the collecting ducts is controlled by a hormone called antidiuretic hormone (ADH) produced by the pituitary gland, situated at the base of the brain. When the blood becomes more concentrated, as happens when an animal is deprived of water, ADH is secreted and causes more water to be absorbed from the collecting ducts so that concentrated urine is produced. When the animal has drunk plenty of water and the blood is dilute, no ADH is secreted and no or little water is absorbed from the collecting ducts, so dilute urine is produced. In this way the concentration of the blood is controlled precisely.

Diagram 12.8 - Summary of the processes involved in the formation of urine

Fresh Water Fish
Although the skin of fish is more or less waterproof, the gills are very porous. The body fluids of fish that live in fresh water have a higher concentration of dissolved substances than the water in which they swim. In other words the body fluids of fresh water fish are hypertonic to the water (see chapter 3). Water therefore flows into the body by osmosis. To stop the body fluids being constantly diluted fresh water fish produce large quantities of dilute urine.

Marine Fish
Marine fish like the sharks and dogfish have body fluids that have the same concentration of dissolved substances as the water (isotonic) have little problem with water balance. However, marine bony fish like red cod, snapper and sole, have body fluids with a lower concentration of dissolved substances than seawater (they are hypotonic to seawater). This means that water tends to flow out of their bodies by osmosis. To make up this fluid loss they drink seawater and get rid of the excess salt by excreting it from the gills.

Marine Birds
Marine birds that eat marine fish take in large quantities of salt and some only have access to seawater for drinking. Bird’s kidneys are unable to produce very concentrated urine, so they have developed a salt gland. This excretes a concentrated salt solution into the nose to get rid of the excess salt.

Diabetes And The Kidney
There are two types of diabetes. The most common is called sugar diabetes or diabetes mellitus and is common in cats and dogs especially if they are overweight. It is caused by the pancreas secreting insufficient insulin, the hormone that controls the amount of glucose in the blood. If insulin secretion is inadequate, the concentration of glucose in the blood increases. Any increase in the glucose in the blood automatically leads to an increase in glucose in the fluid filtered into the kidney tubule. Normally the kidney removes all the glucose filtered into it, but these high concentrations swamp this removal mechanism and urine containing glucose is produced. The main symptoms of this type of diabetes are the production of large amounts of dilute urine containing glucose, and excessive thirst.

The second type of diabetes is called diabetes insipidus. The name comes from the main symptom, which is the production of large amounts of very dilute and “tasteless” urine. It occurs when the pituitary gland produces insufficient ADH, the hormone that stimulates water re-absorption from the kidney tubule. When this hormone is lacking, water is not absorbed and large amounts of dilute urine are produced. Because so much water is lost in the urine, animals with this form of diabetes can die if deprived of water for only a day or so.

Other Functions Of The Kidney
The excretion of urea from the body and the maintenance of water balance, as described above, are the main functions of the kidney. However, the kidneys have other roles in keeping conditions in the body stable i.e. in maintaining homeostasis. These include:
 * controlling the concentration of salt ions (Na+, K+, Cl-) in the blood by adjusting how much is excreted or retained;
 * maintaining the correct acidity of the blood. Excess acid is constantly being produced by the normal chemical reactions in the body and the kidney eliminates this.

Normal Urine
Normal urine consists of water (95%), urea, salts (mostly sodium chloride) and pigments (mostly from bile) that give it its characteristic colour.

Abnormal Ingredients Of Urine
If the body is not working properly, small amounts of substances not normally present may be found in the urine or substances normally present may appear in abnormal amounts.
 * The presence of glucose may indicate diabetes (see above).
 * Urine with red blood cells in it is called haematuria, and may indicate inflammation of the kidney,or urinary tract, cancer or a blow to the kidneys.
 * Sometimes free haemoglobin is found in the urine. This indicates that the red blood cells in the blood have haemolysed (the membrane has broken down) and the haemoglobin has passed into the kidney tubules.
 * The presence of white blood cells in the urine indicates there is an infection in the kidney or urinary tract.
 * Protein molecules are usually too large to pass into the kidney tubule so no or only small amounts of proteins like albumin is normally found in urine. Large quantities of albumin indicate that the kidney tubules have been injured or the kidney has become diseased. High blood pressure also pushes proteins from the blood into the tubules.
 * Casts are tiny cylinders of material that have been shed from the lining of the tubules and flushed out into the urine.
 * Mucus is not usually found in the urine of healthy animals but is a normal constituent of horses’ urine, giving it a characteristic cloudy appearance.

Tests can be carried out to identify any abnormal ingredients of urine. These tests are normally done by “stix”, which are small plastic strips with absorbent ends impregnated with various chemicals. A colour change occurs in the presence of an abnormal ingredient.

Excretion In Birds
Birds’ high body temperature and level of activity means that they need to conserve water. Birds therefore do not have a bladder and instead of excreting urea, which needs to be dissolved in large amounts of water, birds produce uric acid that can be discharged as a thick paste along with the feces. This is the white chalky part of the bird droppings that land on you or your car.

CONCLUSION

BY GIZAW MEKONNEN
 * The excretory system consists of paired kidneys and associated blood supply. Ureters transport urine from the kidneys to the bladder and the urethra with associated sphincter muscles controls the release of urine.
 * The kidneys have an important role in maintaining homeostasis in the body. They excrete the waste product urea, control the concentrations of water and salt in the body fluids, and regulate the acidity of the blood.
 * A kidney consists of an outer region or cortex, inner medulla and a cavity called the pelvis that collects the urine and carries it to the ureter.
 * The tissue of a kidney is composed of masses of tiny tubes called kidney tubules or nephrons. These are the structures that make the urine.
 * High-pressure blood is supplied to the nephron via a tuft of capillaries called the glomerulus. Most of the contents of the blood except the cells and large protein molecules filter from the glomerulus into the (Bowmans) capsule. This fluid flows down a coiled part of the tubule (proximal convoluted tubule) where useful substances like glucose, amino acids and various ions are reabsorbed. The fluid flows to a looped portion of the tubule called the Loop of Henle where water is reabsorbed and then to another coiled part of the tubule (distal convoluted tubule) where more reabsorbtion and secretion takes place. Finally the fluid passes down the collecting duct where water is reabsorbed to form concentrated urine.

Worksheet
Use this Excretory System Worksheet to help you learn the parts of the urinary system, the kidney and kidney tubule and their functions.

Test Yourself
The Urinary System Test Yourself can then be used to see if you understand this rather complex system.

1. Add the following labels to the diagram of the excretory system shown below. Bladder | ureter | urethra | kidney | dorsal aorta | vena cava | renal artery | vein

2. Using the words/phrases in the list below fill in the blanks in the following statements.
 * cortex | amino acids | renal | glucose | water reabsorption | large proteins |
 * bowman’s capsule | diabetes mellitus | secreted | antidiuretic hormone (ADH) | blood cells |
 * glomerulus | concentration of the urine | medulla | nephron |

a) Blood enters the kidney via the ......................... artery.

b) When cut across the kidney is seen to consist of two regions, the outer.............. and the inner..............

c) Another word for the kidney tubule is the...............................

d) Filtration of the blood occurs in the..............................

e) The filtered fluid (filtrate) enters the.............................

f) The filtrate entering the e) above is similar to blood but does not contain.................. or....................

g) As the fluid passes along the first coiled part of the kidney tubule.................. and.................... are removed.

h) The main function of the loop of Henle is.............................................................

i) Hydrogen and potassium ions are.............................. into the second coiled part of the tubule.

j) The main function of the collecting tube is..................................................

k) The hormone...................................... is responsible for controlling water reabsorption in the collecting tube.

Write short answer for following question

l) When the pancreas secretes inadequate amounts of the hormone insulin the condition known as............................... results. This is most easily diagnosed by testing for................................ in the urine.What is Homeostasis?

2. Give 2 examples of homeostasis.

3. List 3 ways in which animals keep their body temperature constant when the weather is hot.

4. How does the kidney compensate when an animal is deprived of water to drink? 6. Describe how panting helps to reduce the acidity of the blood.

/Test Yourself Answers/

Websites

 * http://www.biologycorner.com/bio3/nephron.html Biology Corner. A fabulous drawing of the kidney and nephron to print off, label and colour in with clear explanation of function.
 * http://health.howstuffworks.com/adam-200032.htm How Stuff Works. This animation traces the full process of urine formation and reabsorption in the kidneys, its path down the ureter to the bladder, and its excretion via the urethra. Needs Shockwave.
 * http://en.wikipedia.org/wiki/Nephron Wikipedia. A bit more detail than you need but still good clear explanations and lots of information.

Glossary

 * Link to Glossary


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Anatomy and Physiology of Animals/Reproductive System

Objectives
After completing this section, you should know:
 * the role of mitosis and meiosis in the production of gametes (sperm and ova)
 * that gametes are haploid cells
 * that fertilization forms a diploid zygote
 * the major parts of the male reproductive system and their functions
 * the route sperm travel along the male reproductive tract to reach the penis
 * the structure of a sperm and the difference between sperm and semen
 * the difference between infertility and impotence
 * the main parts of the female reproductive system and their functions
 * the ovarian cycle and the roles of FSH, LH, oestrogen and progesterone
 * the oestrous cycle and the signs of heat in rodents, dogs, cats and cattle
 * the process of fertilization and where it occurs in the female tract
 * what a morula and a blastocyst are
 * what the placenta is and its functions

Reproductive System
In biological terms sexual reproduction involves the union of gametes - the sperm and the ovum - produced by two parents. Each gamete is formed by meiosis (see Chapter 3). This means each contains only half the chromosomes of the body cells (haploid). Fertilization results in the joining of the male and female gametes to form a zygote which contains the full number of chromosomes (diploid). The zygote then starts to divide by mitosis (see Chapter 3) to form a new animal with all its body cells containing chromosomes that are identical to those of the original zygote (see diagram 13.1).

Diagram 13.1 - Sexual reproduction

The offspring formed by sexual reproduction contain genes from both parents and show considerable variation. For example, kittens in a litter are all different although they (usually) have the same mother and father. In the wild this variation is important because it means that when the environment changes some individuals may be better adapted to survive than others. These survivors pass their “superior” genes on to their offspring. In this way the characteristics of a group of animals can gradually change over time to keep pace with the changing environment. This “survival of the fittest” or “natural selection” is the mechanism behind the theory of evolution.

Fertilization
In most fish and amphibia (frogs and toads) fertilization of the egg cells takes place outside the body. The female lays the eggs and then the male deposits his sperm on or at least near them.

In reptiles and birds, eggs are fertilized inside the body when the male deposits the sperm inside the egg duct of the female. The egg is then surrounded by a resistant shell, “laid” by the female and the embryo completes its development inside the egg.

In mammals the sperm are placed in the body of the female and the eggs are fertilized internally. They then develop to quite an advanced stage inside the body of the female. When they are born they are fed on milk excreted from the mammary glands and protected by their parents until they become independent.

Sexual Reproduction In Mammals
The reproductive organs of mammals produce the gametes (sperm and egg cells), help them fertilize and then support the developing embryo.

The Male Reproductive System
The male reproductive system consists of a pair of testes that produce sperm (or spermatozoa), ducts that transport the sperm to the penis and glands that add secretions to the sperm to make semen (see diagram 13.2).

The various parts of the male reproductive system with a summary of their functions are shown in diagram 13.3.

Diagram 13.2. The reproductive organs of a male dog

Diagram 13.3 - Diagram summarizing the functions of the male reproductive organs

The Testicles
Sperm need temperatures between 2 and 10 degrees Centigrade lower than the body temperature to develop. This is the reason why the testes are located in a bag of skin called the scrotal sacs (or scrotum) that hangs below the body and where the evaporation of secretions from special glands can further reduce the temperature. In many animals (including humans) the testes descend into the scrotal sacs at birth but in some animals they do not descend until sexual maturity and in others they only descend temporarily during the breeding season. A mature animal in which one or both testes have not descended is called a cryptorchid and is usually infertile if both testicles have not descended.

The problem of keeping sperm at a low enough temperature is even greater in birds that have a higher body temperature than mammals. For this reason bird’s sperm are usually produced at night when the body temperature is lower and the sperm themselves are more resistant to heat.

The testes consist of a mass of coiled tubes (the seminiferous or sperm producing tubules) in which the sperm are formed by meiosis (see diagram 13.4). Cells lying between the seminiferous tubules produce the male sex hormone testosterone.

When the sperm are mature they accumulate in the collecting ducts and then pass to the epididymisbefore moving to the sperm duct or vas deferens. The two sperm ducts join the urethra just below the bladder, which passes through the penis and transports both sperm and urine.

Ejaculation discharges the semen from the erect penis. It is brought about by the contraction of the epididymis, vas deferens, prostate gland and urethra.

Diagram 13.4 - The testis and a magnified seminiferous tubule

Semen
Semen consists of 10% sperm and 90% fluid and as sperm pass down the ducts from testis to penis, (accessory) glands add various secretion...

Accessory Glands
Three different glands may be involved in producing the secretions in which sperm are suspended, although the number and type of glands varies from species to species.

Seminal vesicles are important in rats, bulls, boars and stallions but are absent in cats and dogs. When present they produce secretions that make up much of the volume of the semen, and transport and provide nutrients for the sperm.

The prostate gland is important in dogs and humans. It produces an alkaline secretion that neutralizes the acidity of the male urethra and female vagina.

Cowper’s glands (bulbourethral glands) have various functions in different species. The secretions may lubricate, flush out urine or form a gelatinous plug that traps the semen in the female reproductive system after copulation and prevents other males of the same species fertilizing an already mated female. Cowper’s glands are absent in bears and aquatic mammals.

The Penis
The penis consists of connective tissue with numerous small blood spaces in it. These fill with blood during sexual excitement causing erection.

Penis Form And Shape
Dogs, bears, seals, bats and rodents have a special bone in the penis which helps maintain the erection (see diagram 13.2). In some animals (e.g. the bull, ram and boar) the penis has an “S” shaped bend that allows it to fold up when not in use. In many animals the shape of the penis is adapted to match that of the vagina. For example, the boar has a corkscrew shaped penis, there is a pronounced twist in bulls’ and it is forked in marsupials like the opossum. Some have spines, warts or hooks on them to help keep them in the vagina and copulation may be extended to help retain the semen in the female system. Mating can last up to three hours in minks, and dogs may “knot” or “tie” during mating and can not separate until the erection has subsided.

Sperm
Sperm are made up of three parts: a head consisting mainly a prominent haploid nucleus which carries the genetic material and also an acrosome, a midpiece containing many mitochondria to provide the energy and a tail that provides propulsion (see diagram 13.5).

Diagram 13.5 - A sperm

A single ejaculation may contain 2-3 hundred million sperm but even in normal semen as many as 10% of these sperm may be abnormal and infertile. Some may be dead while others are inactive or deformed with double, giant or small heads or tails that are coiled or absent altogether.

When there are too many abnormal sperm or when the sperm concentration is low, the semen may not be able to fertilize an egg and the animal is infertile. Make sure you don't confuse infertility with impotence, which is the inability to copulate successfully.

Sperm do not live forever. They have a definite life span that varies from species to species. They survive for between 20 days (guinea pig) to 60 days (bull) in the epididymis but once ejaculated into the female tract they only live from 12 to 48 hours. When semen is used for artificial insemination, storage under the right conditions can extend the life span of some species.

Artificial Insemination
In many species the male can be artificially stimulated to ejaculate and the semen collected. It can then be diluted, stored and used to inseminate females. For example bull semen can be diluted and stored for up to 3 weeks at room temperature. If mixed with an antifreeze solution and stored in “straws” in liquid nitrogen at minus 79oC it will keep for much longer. Unfortunately the semen of chickens, stallions and boars can only be stored for up to 2 days.

Dilution of the semen means that one male can be used to fertilise many more females than would occur under natural conditions. There are also advantages in the male and female not having to make physical contact. It means that owners of females do not have to buy expensive males and the possibility of transmitting sexually transmitted diseases is reduced. Routine examination of the semen for sperm concentration, quality and activity allows only the highest quality semen to be used so a high success rate is ensured.

Since the lifespan of sperm in the female tract is so short and ova only survive from 8 to 10 hours the timing of the artificial insemination is critical. Successful conception depends upon detecting the time that the animal is “on heat” and when ovulation occurs.

The Female Reproductive Organs
The female reproductive system consists of a pair of ovaries that produce egg cells or ova and fallopian tubes where fertilisation occurs and which carry the fertilised ovum to the uterus. Growth of the foetus takes place here. The cervix separates the uterus from the vagina or birth canal, where the sperm are deposited (see diagram 13.6).

Diagram 13.6. - The reproductive system of a female rabbit

Note that primates like humans have a uterus with a single compartment but in most mammals the uterus is divided into two separate parts or horns as shown in diagram 13.6.

The Ovaries
Ovaries are small oval organs situated in the abdominal cavity just ventral to the kidneys. Most animals have a pair of ovaries but in birds only the left one is functional to reduce weight (see below).

The ovary consists of an inner region (medulla) and an outer region (cortex) containing egg cells or ova. These are formed in large numbers around the time of birth and start to develop after the animal becomes sexually mature. A cluster of cells called the follicle surrounds and nourishes each ovum.

The Ovarian Cycle
The ovarian cycle refers to the series of changes in the ovary during which the follicle matures, the ovum is shed and the corpus luteum develops (see diagram 13.7).

Numerous undeveloped ovarian follicles are present at birth but they start to mature after sexual maturity. In animals that normally have only one baby at a time only one ovum will mature at once but in litter animals several will. The mature follicle consists of outer cells that provide nourishment. Inside this is a fluid-filled space that contains the ovum.

A mature follicle can be quite large, ranging from a few millimetres in small mammals to the size of a golf ball in large animals. It bulges out from the surface of the ovary before eventually rupturing to release the ovum into the abdominal cavity. Once the ovum has been shed, a blood clot forms in the empty follicle. This develops into a tissue called the corpus luteum that produces the hormone progesterone (see diagram 13.9). If the animal becomes pregnant the corpus luteum persists, but if there is no pregnancy it degenerates and a new ovarian cycle usually.

Diagram 13.7 - The ovarian cycle showing from the top left clockwise: the maturation of the ovum over time, followed by ovulation and the development of the corpus luteum in the empty follicle

The Ovum
When the ovum is shed the nucleus is in the final stages of meiosis (cell division). It is surrounded by few layers of follicle cells and a tough membrane called the zona pellucida (see diagram 13.8).

Diagram 13.8 - An ovum

The Oestrous Cycle
The oestrous cycle is the sequence of hormonal changes that occurs through the ovarian cycle. These changes influence the behaviour and body changes of the female (see diagram 13.9).

Diagram 13.9 - The oestrous cycle

The first hormone involved in the oestrous cycle is follicle stimulating hormone (F.S.H.), secreted by the anterior pituitary gland (see chapter 16). It stimulates the follicle to develop. As the follicle matures the outer cells begin to secrete the hormone oestrogen and this stimulates the mammary glands to develop. It also prepares the lining of the uterus to receive a fertilised egg. Ovulation is initiated by a surge of another hormone from the anterior pituitary, luteinising hormone (L.H.). This hormone also influences the development of the corpus luteum, which produces progesterone, a hormone that prepares the lining of the uterus for the fertilised ovum and readies the mammary glands for milk production. If no pregnancy takes place the corpus luteum shrinks and the production of progesterone decreases. This causes FSH to be produced again and a new oestrous cycle begins.

For fertilisation of the ovum by the sperm to occur, the female must be receptive to the male at around the time of ovulation. This is when the hormones turn on the signs of “heat”, and she is “in season” or “in oestrous”. These signs are turned off again at the end of the oestrous cycle.

During the oestrous cycle the lining of the uterus (endometrium) thickens ready for the fertilised ovum to be implanted. If no pregnancy occurs this thickened tissue is absorbed and the next cycle starts. In humans and other higher primates, however, the endometrium is shed as a flow of blood and instead of an oestrous cycle there is a menstrual cycle.

The length of the oestrous cycle varies from species to species. In rats the cycle only lasts 4–5 days and they are sexually receptive for about 14 hours. Dogs have a cycle that lasts 60–70 days and heat lasts 7–9 days and horses have a 21-day cycle and heat lasts an average of 6 days.

Ovulation is spontaneous in most animals but in some, e.g. the cat, and the rabbit, ovulation is stimulated by mating. This is called induced ovulation.

Signs Of Oestrus Or Heat

 * When on heat a bitch has a blood stained discharge from the vulva that changes a little later to a straw coloured one that attracts all the dogs in the neighbourhood.
 * Female cats “call” at night, roll and tread the carpet and are generally restless but will “stand” firm when pressure is placed on the pelvic region (this is the lordosis response).
 * A female rat shows the lordosis response when on heat. It will “mount” other females and be more active than normal.
 * A cow mounts other cows (bulling), bellows, is restless and has a discharge from the vulva.

Breeding Seasons And Breeding Cycles
Only a few animals breed throughout the year. This includes the higher primates (humans, gorillas and chimpanzees etc.), pigs, mice and rabbits. These are known as continuous breeders.

Most other animals restrict reproduction to one or two seasons in the year-seasonal breeders (see diagram 13.10). There are several reasons for this. It means the young can be born at the time (usually spring) when feed is most abundant and temperatures are favourable. It is also sensible to restrict the breeding season because courtship, mating, gestation and the rearing of young can exhaust the energy resources of an animal as well as make them more vulnerable to predators.

Diagram 13.10 - Breeding cycles

The timing of the breeding cycle is often determined by day length. For example the shortening day length in autumn will bring sheep and cows into season so the foetus can gestate through the winter and be born in spring. In cats the increasing day length after the winter solstice (shortest day) stimulates breeding. The number of times an animal comes into season during the year varies, as does the number of oestrous cycles during each season. For example a dog usually has 2-3 seasons per year, each usually consisting of just one oestrous cycle. In contrast ewes usually restrict breeding to one season and can continue to cycle as many as 20 times if they fail to become pregnant.

Fertilization
The opening of the fallopian tube lies close to the ovary and after ovulation the ovum is swept into its funnel-like opening and is moved along it by the action of cilia and wave-like contractions of the wall.

Copulation deposits several hundred million sperm in the vagina. They swim through the cervix and uterus to the fallopian tubes moved along by whip-like movements of their tails and contractions of the uterus. During this journey the sperm undergo their final phase of maturation so they are ready to fertilize the ovum by the time they reach it in the upper fallopian tube.

High mortality means only a small proportion of those deposited actually reach the ovum. The sperm attach to the outer zona pellucida and enzymes secreted from a gland in the head of the sperm dissolve this membrane so it can enter. Once one sperm has entered, changes in the zona pellucida prevent further sperm from penetrating. The sperm loses its tail and the two nuclei fuse to form a zygote with the full set of paired chromosomes restored.

Development Of The Morula And Blastocyst
As the fertilised egg travels down the fallopian tube it starts to divide by mitosis. First two cells are formed and then four, eight, sixteen, etc. until there is a solid ball of cells. This is called a morula. As division continues a hollow ball of cells develops. This is a blastocyst (see diagram 13.11).

Implantation
Implantation involves the blastocyst attaching to, and in some species, completely sinking into the wall of the uterus.

The Placenta And Fetal Membranes
As the embryo increases in size, the placenta, umbilical cord and fetal membranes (often known collectively as the placenta) develop to provide it with nutrients and remove waste products (see diagram 13.12). In later stages of development the embryo becomes known as a fetus.

The placenta is the organ that attaches the fetus to the wall of the uterus. In it the blood of the fetus and mother flow close to each other but never mix (see diagram 13.13). The closeness of the maternal and fetal blood systems allows diffusion between them. Oxygen and nutrients diffuse from the mother’s blood into that of the fetus and carbon dioxide and excretory products diffuse in the other direction. Most maternal hormones (except adrenaline), antibodies, almost all drugs (including alcohol), lead and DDT also pass across the placenta. However, it protects the fetus from infection with bacteria and most viruses.

Diagram 13.11 - Development and implantation of the embryo

Diagram 13.12. The fetus and placenta

The fetus is attached to the placenta by the umbilical cord. It contains arteries that carry blood to the placenta and a vein that returns blood to the fetus. The developing fetus becomes surrounded by membranes. These enclose the amniotic fluid that protects the fetus from knocks and other trauma (see diagram 13.12).

Diagram 13.13 - Maternal and fetal blood flow in the placenta

Hormones During Pregnancy
The corpus luteum continues to secrete progesterone and oestrogen during pregnancy. These maintain the lining of the uterus and prepare the mammary glands for milk secretion. Later in the pregnancy the placenta itself takes over the secretion of these hormones.

Chorionic gonadotrophin is another hormone secreted by the placenta and placental membranes. It prevents uterine contractions before labour and prepares the mammary glands for lactation. Towards the end of pregnancy the placenta and ovaries secrete relaxin, a hormone that eases the joint between the two parts of the pelvis and helps dilate the cervix ready for birth.

Pregnancy Testing
The easiest method of pregnancy detection is ultrasound which is noninvasive and very reliable Later in gestation pregnancy can be detected by taking x-rays.

In dogs and cats a blood test can be used to detect the hormone relaxin.

In mares and cows palpation of the uterus via the rectum is the classic way to determine pregnancy. It can also be done by detecting the hormones progesterone or equine chorionic gonagotrophin (eCG) in the urine. A new sensitive test measures the amount of the hormone, oestrone sulphate, present in a sample of faeces. The hormone is produced by the foal and placenta, and is only present when there is a living foal.

In most animals, once pregnancy is advanced, there is a window of time during which an experienced veterinarian can determine pregnancy by feeling the abdomen.

Gestation Period
The young of many animals (e.g. pigs, horses and elephants) are born at an advanced state of development, able to stand and even run to escape predators soon after they are born. These animals have a relatively long gestation period that varies with their size e.g. from 114 days in the pig to 640 days in the elephant.

In contrast, cats, dogs, mice, rabbits and higher primates are relatively immature when born and totally dependent on their parents for survival. Their gestation period is shorter and varies from 25 days in the mouse to 31 days in rabbits and 258 days in the gorilla.

The babies of marsupials are born at an extremely immature stage and migrate to the pouch where they attach to a teat to complete their development. Kangaroo joeys, for example, are born 33 days after conception and opossums after only 8 days.

Signs Of Imminent Birth
As the pregnancy continues, the mammary glands enlarge and may secrete a milky substance a few days before birth occurs. The vulva may swell and produce thick mucus and there is sometimes a visible change in the position of the foetus. Just before birth the mother often becomes restless, lying down and getting up frequently. Many animals seek a secluded place where they may build a nest in which to give birth.

Labour
Labour involves waves of uterine contractions that press the foetus against the cervix causing it to dilate. The foetus is then pushed through the cervix and along the vagina before being delivered. In the final stage of labour the placenta or “afterbirth” is expelled.

Adaptations Of The Fetus To Life Outside The Uterus
The fetus grows in the watery, protected environment of the uterus where the mother supplies oxygen and nutrients, and waste products pass to her blood circulation for excretion. Once the baby animal is born it must start to breathe for itself, digest food and excrete its own waste. To allow these functions to occur blood is re-routed to the lungs and the glands associated with the gut start to secrete. Note that newborn animals can not control their own body temperature. They need to be kept warm by the mother, litter mates and insulating nest materials.

Milk Production
Cows, manatees and primates have two mammary glands but animals like pigs that give birth to large litters may have as many as 12 pairs. Ducts from the gland lead to a nipple or teat and there may be a sinus where the milk collects before being suckled (see diagram 13.14).

Diagram 13.14 - A mammary gland

The hormones oestrogen and progesterone stimulate the mammary glands to develop and prolactin promotes the secretion of the milk. Oxytocin from the pituitary gland releases the milk when the baby suckles. The first milk is called colostrum. It is a rich in nutrients and contains protective antibodies from the mother. Milk contains fat, protein and milk sugar as well as vitamins and most minerals although it contains little iron. Its actual composition varies widely from species to species. For example whale’s and seal’s milk has twelve times more fat and four times more protein than cow’s milk. Cow’s milk has far less protein in it than cat’s or dog’s milk. This is why orphan kittens and puppies cannot be fed cow’s milk.

Reproduction In Birds
Male birds have testes and sperm ducts and male swans, ducks, geese and ostriches have a penis. However, most birds make do with a small amount of erectile tissue known as a papilla. To reduce weight for flight most female birds only have one ovary - usually the left, which produces extremely yolky eggs. The eggs are fertilised in the upper part of the oviduct (equivalent to the fallopian tube and uterus of mammals) and as they pass down it albumin (the white of the egg), the membrane beneath the shell and the shell are laid down over the yolk. Finally the egg is covered in a layer of mucus to help the bird lay it (see diagram 13.15).

Most birds lay their eggs in a nest and the hen sits on them until they hatch. Ducklings and chicks are relatively well developed when they hatch and able to forage for their own food. Most other nestlings need their parents to keep them warm, clean and fed. Young birds grow rapidly and have voracious appetites that may involve the parents making up to 1000 trips a day to supply their need for food.

Diagram 13.15 - Female reproductive organs of a bird

Summary

 * Haploid gametes (sperm and ova) are produced by meiosis in the gonads (testes and ovaries).
 * Fertilization involves the fusing of the gametes to form a diploid zygote.
 * The male reproductive system consists of a pair of testes that produce sperm (or spermatozoa), ducts that transport the sperm to the penis and glands that add secretions to the sperm to make semen.
 * Sperm are produced in the seminiferous tubules, are stored in the epididymis and travel via the vas deferens or sperm duct to the junction of the bladder and the urethra where various accessory glands add secretions. The fluid is now called semen and is ejaculated into the female system down the urethra that runs down the centre of the penis.
 * Sperm consist of a head, a midpiece and a tail.
 * Infertility is the inability of sperm to fertilize an egg while impotence is the inability to copulate successfully.
 * The female reproductive system consists of a pair of ovaries that produce ova and fallopian tubes where fertilization occurs and which carry the fertilized ovum to the uterus. Growth of the fetus takes place here. The cervix separates the uterus from the vagina, the birth canal and where the sperm are deposited.
 * The ovarian cycle refers to the series of changes in the ovary during which the follicle matures, the ovum is shed and the corpus luteum develops.
 * The oestrous cycle is the sequence of hormonal changes that occurs through the ovarian cycle. It is initiated by the secretion of follicle stimulating hormone (F.S.H.), by the anterior pituitary gland which stimulates the follicle to develop. The follicle secretes oestrogen which stimulates mammary gland development. luteinising hormone (L.H.) from the anterior pituitary initiates ovulation and stimulates the corpus luteum to develop. The corpus luteum produces progesterone that prepares the lining of the uterus for the fertilized ovum.
 * Signs of oestrous or heat differ. A bitch has a blood stained discharge, female cats and rats are restless and show the lordosis response, while cows mount other cows, bellow and have a discharge from the vulva.
 * After fertilization in the fallopian tube the zygote divides over and over by mitosis to become a ball of cells called a morula. Division continues to form a hollow ball of cells called the blastocyst. This is the stage that implants in the uterus.
 * The placenta, umbilical cord and fetal membranes (known as the placenta) protect and provide the developing fetus with nutrients and remove waste products.

Worksheet
Reproductive System Worksheet

Test Yourself
1. Add the following labels to the diagram of the male reproductive organs below.
 * testis | epididymis | vas deferens | urethra | penis | scrotal sac | prostate gland

Diagram of the Male Reproductive System

2. Match the following descriptions with the choices given in the list below.
 * accessory glands | vas deferens or sperm duct | penis | scrotum | fallopian tube | testes | urethra | vagina | uterus | ovary | vulva
 * a) Organ that delivers semen to the female vagina
 * b) Where the sperm are produced
 * c) Passage for sperm from the epididymis to the urethra
 * d) Carries both sperm and urine down the penis
 * e) Glands that produce secretions that make up most of the semen
 * f) Bag of skin surrounding the testes
 * g) Where the foetus develops
 * h) This receives the penis during copulation
 * i) Where fertilisation usually occurs
 * j) Ova travel along this tube to reach the uterus
 * k) Where the ova are produced
 * l) The external opening of the vagina

3. Which hormone is described in each statement below?
 * a) This hormone stimulates the growth of the follicles in the ovary
 * b) This hormone converts the empty follicle into the corpus luteum and stimulates it to produce progesterone
 * c) This hormone is produced by the cells of the follicle
 * d) This hormone is produced by the corpus luteum
 * e) This hormone causes the mammary glands to develop
 * f) This hormone prepares the lining of the uterus to receive a fertilised ovum

4. State whether the following statements are true or false. If false write in the correct answer.
 * a) Fertilisation of the egg occurs in the uterus
 * b) The fertilised egg cell contains half the normal number of chromosomes
 * c) The morula is a hollow ball of cells
 * d) The mixing of the blood of the mother and foetus allows nutrients and oxygen to transfer easily to the foetus
 * e) The morula implants in the wall of the uterus
 * f) The placenta is the organ that supplies the foetus with oxygen and nutrients
 * g) Colostrum is the first milk
 * h) Young animals often have to be given calcium supplements because milk contains very little calcium

/Test Yourself Answers/

Websites

 * http://www.anatomicaltravel.com/CB_site/Conception_to_birth3.htm Anatomical travel.  Images of fertilisation and the development of the (human) embryo through to birth.
 * http://www.uchsc.edu/ltc/fert.swf Fertilisation. A great animation of fertilisation, formation of the zygote and first mitotic division. A bit advanced but still worth watching.
 * http://www.uclan.ac.uk/facs/health/nursing/sonic/scenarios/salfordanim/heart.swf Sonic. An animation showing the foetal blood circulation through the placenta to the changes allowing circulation through the lungs after birth.
 * http://en.wikipedia.org/wiki/Estrus Wikipedia. As always, good interesting information although some terms and concepts are beyond the requirements of this level.

Glossary

 * Link to Glossary

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
Past LSAT Explained/Main Idea(RC)

Main Idea (Reading Comprehension) This global question is a perennial favorite RC question. It is important you remember not only what the author is saying but why he is saying. The author is leading you to a certain point. All the LSAT passages are well-written (if convoluted) and scholar piece of writing. Though hidden under the loads of difficult ideas and facts, the main idea itself is pretty evident and unequivocal (otherwise the LSAC will have a hard time defending the answer to 100,000 test takers).

title: Past LSAT Explained/Main Idea(RC)


text:
Past LSAT Explained/Global(RC)

Reading Comprehension Global Questions require that you have read the entire passage in order to answer the question. The question tests your skill in seeing the forest not just the tree. Often the Global questions are easier because there are much more information to work with.

title: Past LSAT Explained/Global(RC)


text:
Wikijunior:Visual Math/form numbers up to 5

1 1 1 1 1 _  _  _  _  _  _  _

2 2 2 2 2 _  _  _  _  _  _  _

3 3 3 3 3 _  _  _  _  _  _  _

4 4 4 4 4 _  _  _  _  _  _  _

5 5 5 5 5 _  _  _  _  _  _  _


text:
Econometric Theory/SLR

$$\begin{align} & Y_{i}=\beta _{1}+\beta _{2}X_{i}+U_{i} \\ & E(U|X)=0 \\ & Var(U|X)=Var(Y|X)=\sigma ^{2} \\ & Y_{i}=\beta _{1}+\beta _{2}X_{i}+U_{i} \\ & \widehat{Y_{i}}=\widehat{\beta _{1}}+\widehat{\beta _{2}}X_{i} \\ & \widehat{U_{i}}=Y_{i}-\widehat{Y_{i}} \\ \end{align}$$

Use of $$\beta_{1}$$ or $$\beta_{0}$$ to denote the Y-intercept is solely discretionary.

$$\begin{align} & \widehat{\beta _{2}}=\frac{\sum{(Y_{i}-\bar{Y}})(X_{i}-\bar{X})}{\sum{(X_{i}-\bar{X})^{2}}} \\ & \widehat{\beta _{1}}=\bar{Y}-\widehat{\beta _{2}}\bar{X} \\ & Var(\widehat{\beta _{2}})=\frac{\sigma ^{2}}{\sum{(X_{i}-\bar{X})^{2}}} \\ & Var(\widehat{\beta _{1}})=\frac{\sum{X_{i}^{2}}*\sigma ^{2}}{n*\sum{(X_{i}-\bar{X})^{2}}} \\ & \widehat{\sigma ^{2}}=\frac{\sum{\widehat{U_{i}^{2}}}}{n-2} \\ \end{align}$$

U and $$\epsilon$$ have both been used to denote the error term.

$$\begin{align} & S_{2}^{2}=\widehat{Var(\widehat{\beta _{2}})}=\frac{\widehat{\sigma ^{2}}}{\sum{(X_{i}-\bar{X})^{2}}} \\ & S_{1}^{2}=\widehat{Var(\widehat{\beta _{1}})}=\frac{\sum{X_{i}^{2}}*\widehat{\sigma ^{2}}}{n*\sum{(X_{i}-\bar{X})^{2}}} \\ & S.E.(\widehat{\beta _{2}})=\sqrt{\widehat{Var(\widehat{\beta _{2}})}} \\ & S.E.(\widehat{\beta _{1}})=\sqrt{\widehat{Var(\widehat{\beta _{1}})}} \\ \end{align}$$

$$S^2$$ is used to denote a sample variance, S.E. standard error.

$$\begin{align} & TSS=\sum{(Y_{i}-\bar{Y})^{2}} \\ & ESS=\sum{(\widehat{Y_{i}}-\bar{Y})^{2}} \\ & RSS=\sum{\widehat{U_{i}^{2}}} \\ \end{align}$$

TSS may also be presented as SST for the Total Sum of Squares, ESS as SSE (error) and RSS as SSR (residuals). Depending on the text, ESS and RSS may become very confusing, as there is great variety in the terminology used.

$$R^{2}=\frac{ESS}{TSS}=1-\frac{RSS}{TSS}$$

$$\widehat{\log (Y)}=\widehat{\beta _{1}}+\widehat{\beta _{2}}\log (X)$$

title: Econometric Theory/SLR


text:
User:Whiteknight/Count Ticker

= About This Page =

The Wikicharts page counter on the toolserver is actively counting page hits for en.wikibooks. The results are listed below. More information about this page can be found here:

 * /About/
 * /Script/

Archives

 * 2007/October

 * 2007/November

 * 2007/December

 * 2008/January

 * 2008/February

= Reports =

title: User:Whiteknight/Count Ticker


text: User:Whiteknight/AnalyticsReport

title: User:Whiteknight/AnalyticsReport


text:
Automobile Repair/Nissan/Maxima (4th Generation)/Replacing the engine thermal transmitter

The Thermal Transmitter is a small thermometer, that reads the coolant temperature and transmits that information to the dash board. This should not be confused with the coolant temperature sensor, that sends the coolant temperature to the ECU (cars computer). The Thermal Transmitter should only be replaced if your dash board is showing bad temperature readings.

Tools/Parts needed

 * A medium size adjustable wrench
 * A Phillips-head screw driver
 * A new thermal transmitter

Procedure

 * If you have a stock intake, remove air box by losing the Phillips-head hose clamp.
 * Then remove the intake duck, by removing the two Phillips-heads attached to the front of the car and pull it out.
 * Now look just to the right of the engine, at the hose that comes out of the engine, it connected to a sort pipe. There are two wires going into it, the one closes to you is the thermal transmitter and the one just behind it is the Coolant Temperature sensor.
 * Remove the cable from the thermal transmitter, it just pulls off.
 * Now use your medium size adjustable wrench, to remove the thermal transmitter (don't worry no antifreeze will not come out).
 * Install the new one with you adjustable wrench and reattach the wire.
 * Now reinstall the intake duck and the air box making sure the Phillips-heads are tight.


text:
Automobile Repair/Nissan/Maxima (4th Generation)/Replacing the engine coolant temperature sensor

The Engine Coolant Temperature Sensor is a small thermometer, that reads the coolant temperature and transmits that information to the ECU (cars computer). This should not be confused with the Thermal Transmitter, that sends the coolant temperature to the dash board. The Engine Coolant Temperature Sensor should only be replaced if your ECU is showing a coolant temperature code and your coolant temperature is fine.

Tools/Parts needed

 * A medium size adjustable wrench
 * A Phillips-head screw driver
 * A new Engine Coolant Temperature Sensor

Procedure

 * 1) If you have a stock intake, remove air box by losing the Phillips-head hose clamp.
 * 2) Then remove the intake duck, by removing the two Phillips-heads attached to the front of the car and pull it out.
 * 3) Now look just to the right of the engine, at the hose that comes out of the engine, it connected to a sort pipe.  There are two wires going into it, the one closest to you is the thermal transmitter and the one just behind it is the Coolant Temperature sensor.
 * 4) Remove the cable from the Coolant Temperature Sensor, you have to push the tab in to get it off (if your having trouble use a screw driver to push it in).
 * 5) Now use your medium size adjustable wrench, to remove the Coolant Temperature Sensor (don't worry no antifreeze will not come out).
 * 6) Install the new one with your adjustable wrench and reattach the wire.
 * 7) Now reinstall the intake duck and the air box making sure the Phillips-heads are tight.


text: User:Whiteknight/BookReport

title: User:Whiteknight/BookReport


text:
Geometry/Chapter 21

A collection of theorems about chords of a circle can be summarized as under.

1.''' If a straight line drawn from the centre of a circle bisects a chord which does not pass through the centre, it cuts the chord at right angles. Conversely, if it cuts the chord at right angles, it bisects it.''' (Euclid III. 3)

2. One circle, and only one, can pass through any three points not in the same straight line.

3.If from a point within a circle more than two equal straight lines can be drawn to the circumference, that point is the centre of the circle. (Euclid III. 9)

4.'''Equal chords of a circle are equidistant from the centre. Conversely, chords which are equidistant from the centre are equal'''. (Euclid III. 14)

title: Geometry/Chapter 21


text:
User:(void*)

qv (void*)

title: User:(void*)


text: User:Whiteknight/BrowserReport

title: User:Whiteknight/BrowserReport


text:
Category:User:Whiteknight/Analytics

These pages are part of my page counting efforts. The most recent page counts can be found at User:Whiteknight/Analytics.

title: Category:User:Whiteknight/Analytics


text:
Category:User:Whiteknight/Outlines

These pages are all outlines for various projects. These are planning pages, not project pages. For a complete list, see my Book Foundry

title: Category:User:Whiteknight/Outlines


text:
Category:User:Whiteknight/New Book Guide

The pages in this category are part of my New book Guide.


text:
Blender 3D: Noob to Pro/Landscape Modeling I: Basic Terrain

Introduction
I worked with a group to make a small animation for class and I was responsible for the environment modeling. I really liked the results of the process I used, so I decided to share it with others. By the end of this tutorial you'll have the know-how to create your own flexible, realistic terrain utilizing multiple textures for different ground types. This tutorial assumes that you have the very basic understanding of using Blender (how to add/remove a mesh, how to change views, etc...) I use the following textures in this demo. Feel free to use them if you don't have something on hand to use.

NOTE: This page uses a different grass texture for licensing reasons (sorry).

Creating the Canvas
The "canvas" that we'll use for our terrain is an evenly spaced grid of vertices. Open a new project, delete the default cube, and add a grid mesh. Use whatever size you want. The more vertices you have, the more detailed and realistic your landscape will appear, but don't get crazy with it since we'll apply subsurfacing at the end to smooth it out. At the same time, you do want enough vertices to prevent sharp edges, and we'll need them in the second tutorial when we cover texture stenciling. So consider how big you want your landscape and try to find a reasonable balance. I like to start with 100x100. The grid will be pretty small, so scale the entire thing up, let's say by a factor of 20. This grid will be used to build our landscape by pulling hills and mountains out of it.

Noob Note: If you don't want to have to delete the default cube every time you open a new file, just delete the cube once so you have the blank window (only lamp and camera left). Then select File - Save default settings or hit Ctrl+U. From now on, each new project you create will start off without the cube.

Molding the Mountains
The key to making good mountains is using the proportional edit mode (OKEY) and constantly adjusting the radius of influence. If you've already gone through the Mountains Out Of Molehills tutorial then this section will be familiar. One major difference is that in this tutorial I recommend rotating the 3D view around so you have a good view of all three axes instead of working in the front or sides view. Using the proportional editing tool affects multiple vertices, and it helps to see what effect your changes are having as you make them.
 * Go ahead and turn on proportional editing, either by pressing OKEY or clicking on the grey ring on the 3D View header. You have to be in Edit Mode to select this option. Once proportional editing is enabled, the ring will appear orange and a new drop-down menu will appear next to it with different falloff styles.  Select Smooth if it is not already selected.
 * Select any random vertex and grab it (GKEY). You will see a ring around the vertex you are grabbing.  This is the radius of influence, and only vertices inside this ring are affected by the transformation.  If you are doing this in the orthographic view from the front, side, or top, then this will be obvious.  But if you're at a view where you can see all three axes, then it may be less obvious.
 * Restrict movement to the z-axis (ZKEY) and translate the vertex upward. Throughout this entire process you ONLY want to translate along the z-axis.  If you start moving vertices in the x or y directions, things become distorted and you get some nasty creases.  Play around with adjusting the size of the radius of influence (Mouse Wheel) to get steeper or flatter hills.

Note: You'll notice in my screenshot that I have reduced the size of my grid. For simplicity's sake, I didn't feel like filling an entire 100x100 grid with mountains since this can take some time.
 * Keep repeating this process with different size radii and different heights until you have a decent mountain range, but leave an area flat. We'll be using that spot later in the second tutorial.  Don't be afraid to occasionally translate some vertices down instead of up to create depressions in the hills.  Remember, variety is the spice of life.  Very few things in nature are naturally geometric, so mix up your hills and especially make sure they overlap.  How often do you see a nice, smooth hill all by itself in nature?

 * Well now, that's looking pretty good! Now, there's one problem with our hills so far.  They're too smooth!  Let's bumpify them a little.  Change the falloff type from Smooth to Random.
 * Select a single vertex and grab it (GKEY). We're still working on the z-axis only, to restrict your movement with the ZKEY.  Now when you move the vertex up and down, all vertices in the radius of influence will also move but with a random falloff instead of smoothly.  It only takes a little movement to get the effect we want, so something around 0.5-1.0 is enough.  Mix up moving up and down with different vertices, again to add variety to the scene.
 * Once you have your landscape the way you like it, add a subsurf modifier under the Editing tab (F9) and select Catmull-Clark. This will smooth out your terrain a little so that it's not too rough.  Given the number of vertices you already have, it's not necessary to have a higher render value than 1 unless you just REALLY want it to be smooth, but I don't recommend it.  Land is supposed to be bumpy and rocky, we just don't want sharp edges.

Noob note: If you're making mountains using Random Falloff and the peaks stick up too much: in Edit mode, select the points in the area around the peak using circle select, then press WKEY and click 'Smooth' until you're satisfied (or, in the Editing tab (F9), click the 'Smooth' button).

Useful Tip Proportional editing can be used on multiple vertices simultaneously. This is especially useful if you're trying to create a cliff face or a river bed. Use the box tool (BKEY) to select a group of vertices and then translate them. Keep in mind that the size of the radius of influence determines how many vertices around EACH VERTEX will be influenced. So suppose you have a 5 vertex radius, that means that 5 vertices all the way around your selected region will be influenced.

Texturing the Terrain
Alright! We've got some pretty nice hills now! But there's still a few problems. Hills shouldn't be white, and hills shouldn't be SHINY! Let's dress them up a little, shall we?
 * With your landscape selected, go to the Shading Panel (F5) and add a new material.
 * Under the Shaders tab, drop the Specular value to 0.
 * Go to the Texture tab (F6) and add a new texture.
 * In the Texture Type drop down menu, select Image.
 * Two new tabs will appear. In the Image tab, click Load and load a texture from file.
 * In the Map Image tab, increase the Xrepeat and Yrepeat. Depending on the size of your terrain and the image that you use (please use something that tiles!), these values will vary.  I've used 10 for each in this tutorial.

(Noob note: Render the scene (F12) to see the applied texture) (Noob note: A quicker way to do this is by using the render preview tool, 3d view window - render preview, View--> Render Preview or press SHIFT--> PKEY) (Noob note: you may also select shaded in the Viewport Shading menu next to where you select object mode or edit mode to see your texture on your mountains without rendering, however it does slow your computer down some which could make editing frustrating. So only do this if you want to see what your textures look like, then switch back to solid for more editing.)

 * Finally, let's do something about the lighting. Go to Object Mode (TAB) if you're not already there and select the lamp.  Choose the Shading Panel (F5) and then click the icon that looks like a light bulb to display the Lamp buttons. Change the lamp to a sun and up the energy to 1.5.  You may also need to increase the distance if your terrain is large, or rotate it around if you don't like where it's pointing.  The dashed line coming out of the light is the direction.  Play around with different angles and energy values for the sun to get different times of day in your scene.

And there you have it! Your landscape is now textured with some nice grass to make it look a little more realistic. Play around with hill sizes and roughness if you're not satisfied with your landscape, but try not to be too picky. Nature shouldn't look too sculpted. Remember, you won't notice a change in texture unless you render your image.

NOTE If you went with the suggested 100x100 grid, the rendering process could definitely take some time depending on your system, especially if you have ray tracing and shadows enabled. To boost the rendering speed, go to the Scene panel (F10) and under Rendering, disable the buttons that say Shadow and Ray. Also note that because we've created some hills, your camera may now be under the terrain. Switch to the camera view (NUM0) to see what your camera sees and move it if you need to.

Join us next time as we explore how to make the landscape look even better using texture stenciling!

Reader Contributions
I'm mainly doing this so the hills look better and more realistic. Reading this will consume more time than doing it. I'm making everything clear for beginners. It will only take about 8 minutes more for your hills to end up like this:

 * 1) First step to achieve it is to switch from the default lamp to Sun.
 * 2) You do this by clicking on the default and go to the shading tab (F5)
 * 3) Click on Sun.
 * 4) Go to rotate manipulator mode with Ctrl Alt R.
 * 5) Rotate the sun until the dotted line is in your desired position. That is where the main energy will go. It will differ if you want to achieve the different time of day. You can make the distance greater or less with dist.. I kept mine at default 30.
 * 6) Now let's make more realistic, paler sunlight.
 * 7) In the RGB slider, set R for 1, G for 1, and B for .848.
 * 8) Set energy for 1.63. This will all differ for different times of day, so set your east and west in your head, and the later into the day, the further the sun to the west and the more orange. For midday, keep the energy on 1.63 and put the sun right above your hills. I set mine for earlier in the morning.
 * 9) Now click on the picture of a globe to change the background.
 * 10) Click on the blend button for a more realistic looking sky. On the left of the World toolbar, that will be the color of lower down in the sky and the right sliders will be the color of the top of the sky. Naturally, the top should be darker blue than the bottom.
 * 11) It will differ for different times of the day. So you might want something different from this. But I set up mine for the morning using the settings below:
 * 12) * The left HoRGB sliders to 0.50, 0.68, and 1.
 * 13) * The right ZeRGB sliders to 0.11, 0.25, and 0.66.
 * 14) Now for the texture. This won't differ for the times of day, but it will differ for what type of landscape you want.
 * 15) Download a nice texture from google or an artists website.
 * 16) Go back to Blender, go to Texture buttons (F6)
 * 17) Click add new
 * 18) Select image for the texture type
 * 19) Go to the image toolbar, and upload the texture. Blender will only allow you to upload from the Blender documents, unless if you click on the up and down arrows on the top left of the screen and choose the place where you saved the texture (or picture).
 * 20) After uploading, the X and Y repeats should be smallish, like 6x6, so the changes aren't noticeable. It will look ugly in the preview, but it will look nice after its wrapped.
 * 21) Render, and 1 minute later, voila! Those are nice looking hills!
 * 22) Now boast in front of your friends!

Noob Note: You need to have your landscape selected if you are in object mode to change the texture, otherwise it will change the texture of the world.

Reader Contributions 2
You can have an even better result if you use the texture to "bumpmap" the mountains.
 * 1) Press F5 until you are into Material Buttons
 * 2) Select the Map to tab
 * 3) Click on Nor once (the Col option must stay selected as well)
 * 4) Slide the Nor slider to 5 or more (might differ depending on texture size and repeat options)
 * 5) Render with F12

Reader Contributions 3
Alternately from making the hill model manually, you can use a program like L3DT. It uses various algorithms to generate very detailed and realistic terrain heightmaps. It also lets you edit them in a more intuitive way than Blender does. After you have L3DT make your height map, you can export it as a .x file, which you can import into Blender. Noob Note: That can be done by going into File->Import->DirectX(.x). And there you have a very realistic landscape mesh with a lot less work. (Noob Question: I want to use Unity3d game engine to create a game, but i want to use blender to create landscapes. To create massive world landscapes, does anybody have any tips? as Unity limits any mesh to 65000 vertices, which i've already passed with my method without doing half the map.)

-If you are using unity 3d just use it for the terrain. Download the terrain toolbox and just use .raw images. Or simply generate from there and save. 65,000 verts is plenty btw. If you insist on using blender for the terrain then model a high poly terrain fist consisting of around 1 mil+ verts. bake the normal map and ambient occlusion decimate your terrain to around 10k or w/e looks good for the game. Then bam you got 10k terrain that looks like 1mil. But to be honest blender terrain texturing is a pain compared to unity. Anyhow hope that helps.


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User:Orwell Mill~enwikibooks

Hello!

My name is António Pequeno and I am 23 years old. I live and work in Évora, Portugal. I graduated in management from the University of Évora and now I'm doing trainig as an accountant and manager at Caritas in my Diocese.

Besides management I'm interested in economics, history, law and languages. Now I am trying to learn russian and arabic.

I'm a Benfica fan.

title: User:Orwell Mill~enwikibooks


text:
Talk:Muggles' Guide to Harry Potter/Characters/Harry Potter

After Hogwarts
The following appeared on Rowling's official site for the month of October 2007:

Wizard of the Month: Harry Potter (1980 - )

The Boy Who Lived, only known survivor of the Avada Kedavra curse and conqueror of Lord Voldemort, also known as Tom Riddle. Harry Potter joined the reshuffled Auror Department under Kingsley Shacklebolt at age 17, rising to become Head of said department in 2007.

The implication is that Harry became an Auror within two months of the death of Voldemort (at least entering the three years training that McGonagall talks about at that point) and was Head of the department within seven years. Hmm.

Is there anyone
who also thinks that the choice of Auror for profession is an authorial mistake? Following the consistent line of the books until suddenly for no real reason (except, as Harry himself mentions, a flattering Death Eater in disguise, and the desire to spite Umbridge), there is one obvious thing Harry Potter would be going to do. Finishing Voldemort off for good, and then in the peace of the Wizarding World, play Quidditch for England, in Seeker position. - After growing out of the age for professional sports, one might imaginate a professorship at Hogwarts (except for the fact that Hogwarts seems to require celibacy from his teachers?), under the influence of Dumbledore whose greatest pleasure lies in teaching, as it does for Harry Potter when teaching Dumbledore's Army. It is true that his subject would of course be Defence Against the Dark Arts, but why as a practitioner and not a teacher?--131.159.76.213 (discuss) 19:15, 15 March 2017 (UTC)

 * I sort of suspect the author was sort of casting around for a career, much as Harry was prior to the Careers conference in book 5. I argue that Hogwarts doesn't require celibacy; that's more of a lack of awareness on the part of the students. (I'll point at Hagrid and Olympe, for starters, and will mention that McGonagall, according to the author, was married and widowed. One cannot imagine Lockhart as being celibate... Dumbledore is, of course, a special case, and I suspect strongly that there are protective charms that prevent any of the teachers from concerning themselves with any of the students.) But yes, I can't help thinking that Harry as Quidditch star, and then as teacher, is a better fit for his personality than the plodding policeman's round of an Auror after Voldemort gets snuffed. Chazz (talk) 02:53, 16 March 2017 (UTC)


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User talk:Moohasha

Welcome message
Come introduce yourself at the new users page. If you have any questions, you can ask there or contact me personally. Urbane  (Talk)   (Contributions)  18:15, 1 October 2007 (UTC)

Image Problems
Thanks for uploading images on Wikibooks. However, the images may soon be deleted unless we can determine the copyright holder and copyright status. The Wikimedia Foundation is very careful about the images included in Wikibooks because of copyright law (see Wikibooks' Copyright policy).

The copyright holder is usually the creator, the creator's employer, or the last person who was transferred ownership rights. Copyright information on images is signified using copyright templates. The three basic license types on Wikibooks are open content, public domain, and fair use. Find the appropriate template in Image copyright tags and place it on the image page like this:.

Please signify the copyright information on all images you have uploaded or will upload. Remember that images without this important information or giving false information can be deleted by an administrator. If you have any questions, ask them at the Staff lounge. Thank you. Urbane  (Talk)   (Contributions)  19:23, 1 October 2007 (UTC)
 * Thanks for updating the license info on those images! I think you missed a few though - I found this one. To find the others, use the untagged and unlicensed tabs at the top of your userpage. – Mike.lifeguard  | talk 01:49, 2 October 2007 (UTC)
 * When you update license info, please edit the image page instead of uploading the image again and using the drop-down box. There seems to be some error happening - the license template doesn't get added if you do it that way for reasons unknown. Thanks! – Mike.lifeguard  | talk 03:33, 5 October 2007 (UTC)

Thank you thank you(!) for uploading images with good license and source info! This makes my life a ton easier :) – Mike.lifeguard  | talk 00:11, 14 December 2007 (UTC)

title: User talk:Moohasha


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User:Whiteknight/Scripting Wikibooks

This book is for wikibookian programmers who are interested in using Javascript to modify and extend the Wikibooks interface for personal use. We will cover some of the functions that exist in MediaWiki:common.js as well as other global javascripts, and how they can be used to make scripting tasks easier. --Whiteknight (Page) (Talk) 18:39, 1 October 2007 (UTC)

The Plan

 * Target Audience: Wikibookians who are interested in scripting.
 * Scope: Will cover the MediaWiki:Common.js file, and common Javascript tasks.
 * Prerequisites: Javascript, Using Wikibooks
 * Corequisites: none.

Wikibooks Scripts Overview

 * Included Scripts
 * Global Variables
 * Wikibits.js
 * Site Javascript
 * Common.js
 * Personal Javascripts
 * Extension Scripts

Common Tasks

 * addOnloadHook
 * Importing Scripts
 * Adding Links and Tabs
 * Changing Text and Appearance
 * Editing Tools

Advanced Tasks

 * AJAX Requests
 * Semiautomated Editing
 * Creating Interactive Forms
 * Cross-Browser Issues

Existing Scripts

 * Existing User Scripts
 * Extending common.js

Resources

 * Javascript

title: User:Whiteknight/Scripting Wikibooks


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Corps-Style Marching/Technique/Posture

The primary purpose of proper posture in corps-style marching is to present the performer as a confident, aggressive individual. This is accomplished by making every element of the body, from the feet to the head, appear as tall and big and strong as possible, and relaxing muscles to eliminate all appearance of tension.

For wind players, posture also serves the secondary purpose of eliminating constrictions in the airstream from the bottom of the lungs to the mouth. This improves dynamic flexibility, as well as tone quality and the breath support that is needed to maintain it.

All other elements of corps-style marching depend on proper posture to be effective.

Weight Distribution
Proper distribution of the body's weight along the feet is the most fundamental part of maintaining correct posture. Incorrect weight distribution makes it impossible to maintain upper-body posture while moving (especially at slower tempos) and can create great difficulty in standing still for long periods of time.

With both feet flat on the ground, approximately 70% of the body's weight should be supported by the balls of both feet, and the remaining 30% on the heels. When done properly, in combination with the rest of the elements described in this chapter, this will cause the entire body to be straight up and down.

Most performers, when standing properly, will actually feel as if they are leaning forwards somewhat. This is because most people typically lean back slightly when they stand, so that actually standing perfectly vertical is noticeably "more forwards" than they are used to. Some performers, upon noticing this sensation, will actually force themselves to lean backwards so that they feel like they are standing straight up and down. Others, knowing that they should feel as if they are leaning forwards, will actually introduce a deliberate forward lean into their posture (usually at the waist, although sometimes at the ankles), causing them to actually be leaning forwards. Although both of these tendencies are trivial for an instructor, who can see the performer's entire body, to notice and correct, the performer himself can notice and correct these flaws by paying attention to the distribution of weight on his feet.

Proper weight distribution, in addition to being the most fundamental part of keeping the entire body straight, is also essential for proper fluid movement. As will be explained later, with every step the performer takes the entire weight of the body must be shifted from one foot to the other. By putting most of the weight towards the front of his foot, the performer is better able to control his momentum and therefore both the direction and timing of his steps.

Foot Placement
When standing still, feet are generally placed either alongside each other, parallel and pointing straight ahead, or with ankles together, toes pointed 45 degrees apart (22.5 degrees on either side of straight ahead). The first method is known generally as "feet-forward", while the second is typically referred to as "feet-45". Feet-45 is widely considered to be more aesthetically pleasing than feet-forward, and is also a way of paying homage to marching music's military roots, but is considerably more difficult to clean. While feet-forward is trivial to teach and understand, feet-45 relies on the performer's muscle memory to understand, which requires that it be taught properly in the first place.

To ensure similar angles throughout the ensemble, groups that use feet-45 typically have guides made of wood or heavy cardboard that they can place between the performer's feet to set them at the correct angle. The performer lines his feet up along both arms of the footguide and memorizes the feeling in his ankles and upper thigh, and then recreates that feeling whenever he is standing with the ensemble.

title: Corps-Style Marching/Technique/Posture