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NOTE: This system is also called the "Urinary System"

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NOTE: This system is also called the "Urinary System"

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Introduction
The various activities of the body create waste by-products that must be expelled in order to maintain health. To excrete certain fluid wastes, the body has a specialized filtering and recycling system known as the urinary, or excretory, system. Solid wastes are eliminated, or egested, through the large intestine ( see digestive system).

In most mammals, including humans, wastes are absorbed from tissues into the passing bloodstream and transported to one of two identical organs called kidneys. In the kidneys, wastes and excess water are removed from the blood as urine. The urine then passes through tubes, called ureters, into a saclike organ called the bladder. From the bladder the urine is excreted, or passed out of the body, through another tube called the urethra.

The Human Urinary System
In the kidneys, excess water and useful blood components such as amino acids, glucose, ions, and various nutrients are reabsorbed into the bloodstream, leaving a concentrated solution of waste material called final, or bladder, urine. It consists of water, urea (from amino-acid metabolism), inorganic salts, creatinine, ammonia, and pigmented products of blood breakdown, one of which (urochrome) gives urine its typically yellowish color. Any substances that cannot be reabsorbed into the blood remain in the urine.

From the kidneys, urine is carried through the ureters by waves of contractions in the ureteral walls. The ureters pass urine to the bladder for temporary storage. The bladder is a muscular organ at the bottom of the abdomen that expands like a sack as it fills. The bladder of an average adult human is uncomfortably distended when it holds a volume of about ¹/ ₃ quart (320 milliliters) of urine. When the bladder is full, nerve endings in the bladder wall are touched off. Impulses from the nerve endings are carried to the brain, triggering the bladder walls to contract and the sphincter, a ringlike muscle that guards the entrance from bladder to urethra, to relax. The response to the nerve signals is part involuntary and part learned and voluntary. Now urination can take place through the urethra, a tube lined with mucous membranes. The male urethra ends at the tip of the penis; the female urethra ends just above the entrance to the vagina. Normally the bladder empties completely. ( See also anatomy, human.)

Urinary Systems of Other Species
The urinary system of most nonmammalian vertebrates also includes paired kidneys and ureters, and, except for birds, a bladder for the temporary storage of urine. The urinary bladders of amphibians are simply pockets in an internal chamber called the cloaca. The urinary bladders of fishes are expandable parts of the urinary duct. With the exception of ostriches and rheas, birds do not have a urinary bladder.

The composition of urine and the manner in which it is excreted varies from animal to animal. Urine's composition tends to mirror the water needs of the organism. Freshwater animals usually excrete very dilute urine. Marine animals tend to combat water loss to their salty environment by excreting concentrated urine. Terrestrial animals usually retain water and secrete a highly concentrated urine.

In most birds, reptiles, and terrestrial insects, the end product of amino-acid metabolism is not water-soluble urea but insoluble uric acid. The urine of birds and reptiles is a whitish, aqueous suspension of uric-acid crystals that is passed into an internal chamber called the cloaca. Here the urine is mixed with fecal material before it is expelled. The urine of terrestrial insects is solid and in some cases, instead of being excreted, is stored as pigment in the body.

The urinary system, like any other part of the body, is occasionally subject to breakdowns. One disorder of the urinary system is a blockage in the urethra, bladder, or ureters. Disorders of this type, called urinary tract obstruction, cause urine to dam up in the bladder or the kidneys. The condition may be congenital (existing from birth) or it may be caused by tumors, mineral deposits that form stones, or other physical disorders. Other urinary-system disorders include kidney malfunction or kidney diseases, which can lead to an accumulation of wastes in the body-a condition called uremia ( see human disease).

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Introduction The various activities of the body create waste by-products that must be expelled in order to maintain health. To excrete certain fluid wastes, the body has a specialized filtering and recycling system known as the urinary, or excretory, system. Solid wastes are eliminated, or egested, through the large intestine ( see digestive system).

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(Article) Kids Health--Kidneys and Urinary Tract (teens)

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(Article) Kids Health--Kidneys and Urinary Tract (teens)

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What Are the Kidneys and Urinary Tract?

The urinary tract is one of the systems that our bodies use to get rid of waste products. The kidneys are the part of the urinary tract that makes urine (pee). Urine has salts, toxins, and water that need to be filtered out of the blood. After the kidneys make urine, it leaves the body using the rest of the urinary tract as a pathway.

What Are the Parts of the Urinary Tract?

People usually have two kidneys, but can live a normal, healthy life with just one. The kidneys are under the ribcage in the back, one on each side. Each adult kidney is about the size of a fist.

Each kidney has an outer layer called the cortex, which contains filtering units. The center part of the kidney, the medulla (pronounced: meh-DUH-luh), has fan-shaped structures called pyramids. These drain urine into cup-shaped tubes called calyxes (pronounced: KAY-luh-seez).

From the calyxes, pee travels out of the kidneys through the ureters (pronounced: YUR-uh-ters) to be stored in the bladder (a muscular sac in the lower belly). When a person urinates, the pee exits the bladder and goes out of the body through the urethra (pronounced: yoo-REE-thruh), another tube-like structure. The male urethra ends at the tip of the penis; the female urethra ends just above the vaginal opening.

What Do the Kidneys Do?

Kidneys have many jobs, from filtering blood and making pee to keeping bones healthy and making a hormone that controls the production of red blood cells.

The kidneys also help regulate blood pressure, the level of salts in the blood, and the acid-base balance (the pH) of the blood. All these jobs make the kidneys essential to keeping the body working as it should.

How Do the Kidneys and Urinary Tract Work?

Blood travels to each kidney through the renal artery. The artery enters the kidney at the hilus (pronounced: HY-luss), the indentation in middle of the kidney that gives it its bean shape. The artery then branches so blood can get to the nephrons (pronounced: NEH-fronz) - 1 million tiny filtering units in each kidney that remove the harmful substances from the blood.

Each of the nephrons contain a filter called the glomerulus (pronounced: gluh-MER-yuh-lus). The fluid that is filtered out from the blood then travels down a tiny tube-like structure called a tubule (pronounced: TOO-byool). The tubule adjusts the level of salts, water, and wastes that will leave the body in the urine. Filtered blood leaves the kidney through the renal vein and flows back to the heart.

Pee leaves the kidneys and travels through the ureters to the bladder. The bladder expands as it fills. When the bladder is full, nerve endings in its wall send messages to the brain. When a person needs to pee, the bladder walls tighten and a ring-like muscle that guards the exit from the bladder to the urethra, called the sphincter (pronounced: SFINK-tur), relaxes. This lets pee go into the urethra and out of the body.

What Can Help Keep the Kidneys and Urinary Tract Healthy?

To help keep your kidneys and urinary tract healthy:

Get plenty of exercise.

Eat a nutritious diet.

Stay hydrated.

For girls: Wipe from front to back after pooping so germs don't get into the urethra.

Avoid bubble baths, sitting in the tub after shampoo has been used, and scented soaps. These can irritate the urethra.

Wear cotton underwear.

Promptly change out of wet bathing suits.

Go for regular medical checkups.

Talk to your doctor before taking any supplements or herbal treatments.

Let the doctor know about any family history of kidney problems, diabetes, or high blood pressure.

Let the doctor know if you have any swelling or puffiness, have pain with peeing, need to pee often, have foamy urine or blood in the urine, or are constipated.

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The urinary tract is one of the systems that our bodies use to get rid of waste products. The kidneys are the part of the urinary tract that makes urine (pee). Urine has salts, toxins, and water that need to be filtered out of the blood.

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Urinary System| How your Urinary System Works | Urinary System - Parts & Function | Video for Kids

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(image search) Google--Excretory system vector logo

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(image search) Google--Excretory system vector logo

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excretory system vector logo - Google Search

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png human body flat shading vector image urinary kidney diagram infographics vector anatomy bladder

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diagram nephron human anatomy human beings function organs model urinary quiz

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(Article) Kids Health--Your Urinary System (kids)

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(Article) Kids Health--Your Urinary System (kids)

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Pee is one of the first body fluids a kid learns about. You probably learned about pee (also called urine) when you were little and started using the toilet instead of diapers. Now that you're older, you can understand much more about the amazing yellow stuff called pee.

Parts of the Urinary Tract

You drink, you pee. But urine is more than just that drink you had a few hours ago. The body produces pee as a way to get rid of waste and extra water that it doesn't need. Before leaving your body, urine travels through the urinary tract.

The urinary tract is a pathway that includes the:

kidneys: two bean-shaped organs that filter waste from the blood and produce urine

ureters: two thin tubes that take pee from the kidney to the bladder

bladder: a sac that holds pee until it's time to go to the bathroom

urethra: the tube that carries urine from the bladder out of the body when you pee

The kidneys are key players in the urinary tract. They do two important jobs - filter waste from the blood and produce pee to get rid of it. If they didn't do this, toxins (bad stuff) would quickly build up in your body and make you sick. That's why you hear about people getting kidney transplants sometimes. You need at least one working kidney to be healthy.

You might wonder how your body ends up with waste it needs to get rid of. Body processes such as digestion and metabolism (when the body turns food into energy) produce wastes, or byproducts. The body takes what it needs, but the waste has to go somewhere. Thanks to the kidneys and pee, it has a way to get out.

When you're asked to give a urine sample during a doctor's visit, the results reveal how well your two kidneys are working. For example, white blood cells in the urine can be a sign of an infection.

Pee also is a way for your body to keep the right amount of water. Did you ever notice that if you drink a lot, you pee more and the pee is pale yellow? That's because your body is getting rid of extra water and your pee has more water in it than usual.

What's Pee Made Of?

Let's talk more about how the kidneys filter blood. When blood goes through the kidneys, water and some of the other stuff that is in blood (like protein, glucose, and other nutrients) go back into the bloodstream, while the waste and excess stuff is taken out. Urine is what is left behind. But what is it exactly?

Urine contains:

water

urea, a waste product that forms when proteins are broken down

urochrome, a pigmented blood product that gives urine its yellowish color

salts

creatinine, a waste product that forms with the normal breakdown of muscle

byproducts of bile from the liver

ammonia

You've Got to Go!

Once pee is produced, it travels from the kidney to the bladder, where it's stored until you need to go to the bathroom. The bladder expands as it fills; when it's full, nerve endings in the bladder wall send a message to the brain that you need to pee.

When you're in the bathroom, ready to go, the bladder walls contract and the sphincter (a ringlike muscle that guards the exit from the bladder to the urethra) relaxes. The urine then flows from the bladder and out of the body through the urethra. For boys, the urethra ends at the tip of the penis. For girls, it's in front of the vaginal opening.

Urinary Tract Health

You might not think much about peeing or your urinary tract, but here's how you can help keep everything flowing as it should:

Drink enough fluids. There's no magic amount, but be sure to drink plenty of water, especially when it's warm out or you're exercising and playing.

For girls: Wipe from front to back, especially after going poop. Because of where the urethra is for girls, it's easy for bacteria from poop to get in that area. If some of those bacteria end up in the urinary tract, you could get an infection known as a UTI (urinary tract infection).

For everyone: Go to the bathroom when you need to go. Holding too long isn't good for your urinary tract - and it can lead to accidents. Uh-oh!

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Pee is one of the first body fluids a kid learns about. You probably learned about pee (also called urine) when you were little and started using the toilet instead of diapers. Now that you're older, you can understand much more about the amazing yellow stuff called pee. You drink, you pee.

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