Excretory+System

Where are the structures and function, communication enzymes & hormones? Not well organized! No flow!
=__**About The Excretory System:**__=

= Kidneys =
 * The excretory system is a regulatory system that helps to maintain homeostasis within the body
 * The excretory system eliminates wastes and functions in osmoregulation.
 * Excretory System in Vertebre:
 * Kidneys, ureters, urinary bladder, urethra, renal artery, renal vein
 * Lungs: excrete carbon dioxide
 * Skin: excretes water, salts, and a small amount of urea (in sweat)
 * ====== Kidneys are the major bodily organ in excretion. ======
 * Small, bean shaped organs.
 * Blood enters the kidney through the renal artery, and exits the kidney through the renal vein
 * Urine exits the kidney through the ureter
 * The ureter from each kidney goes to the urinary bladder
 * Urine leaves the body through the urethra

= How is the excretory system regulated? = = Regulation of the kidney: = = = water and salt reabsorption are subject to a combination of nervous and hormonal controls in the kidney. the kidney regulated blood pressure and water content in blood. Nephrons: the units that make up the kidney. Blood enters the nephron through an arteriole, impurities are filtered out and emptied. The nephron has three functions: Excretory systems regulate the chemical composition of body fluids by removing metabolic wastes and retaining the proper amounts of water, salts, and nutrients. Components of this system in vertebrates include the kidneys, liver, lungs, and skin. Most absorbtion of nutrients happens in the small intestine.
 * 1) Glomerular filtration of water and solutes from the blood.
 * 2) Tubular reabsorption of water and conserved molecules back into the blood.
 * 3) Tubular secretion of ions and other waste products from surrounding capillaries into the distal tubule.

Water absortion is regulated by ADH, the antidiuretic horomone.The ADH is released from the pituitary gland in the brain, puts more water into the blood and acts to increase water absorbtion in kidneys.


 * __EXC__ITING FACTS ABOUT THE __EXC__RETORY SYSTEM:[[image:http://profile.ak.fbcdn.net/hprofile-ak-ash2/41802_497172915636_1736427_n.jpg width="92" height="95"]] **


 * We produce almost one quart of saliva every day.
 * Saliva is 98% water and only 2% enzymes.
 * Length of the digestive tract is about 30 feet.
 * Food stays in the stomach for almost 2 to 3 hours.
 * The small intestine is almost 20 feet long.
 * Food takes almost 4 hours to travel through the small intestine.
 * The large intestine measures up to 5 feet in length.
 * We excrete solid waste material through the anus, when the sphincter muscles lining it, relax.
 * Liver and pancreas are not a part of the digestive tract but they help in digestion by secreting powerful enzymes.

= How do kidneys pass on waste to the rest of the excretory system? = === Your kidneys have millions of **//nephrons//**, which are tubes that act as filters. Blood that has been used goes from your heart to a junction of tiny vessels called **//glomeruli//** inside the nephrons. Inside the glomeruli, positive nutrients such as sugars, proteins, salts, minerals, urea, and extra water get filtered out of the kidneys. Further into the nephron, some nutrients and water are reabsorbed into tiny blood vessels called **//capillaries//**, then are recycled through the blood. The extra water and urea then go down the //ureter// to the bladder and are flushed out of the body. ===



Fun Fact: Once about a cup of urine is collected in the bladder, you feel the urge to urinate, or pee.
=The Bladder! = ===Your bladder is a stretch bag that holds about four cups of fluid. The Sphincter muscles are a group of muscles in the shape of a circle that tighten and act as a trapdoor. There are sphincter muscles both at the base of the ureter and at the bottom of the bladder. The sphincter muscles at the base of the ureter tighten so that urine doesn't get backed up into the body. The muscles at the bottom keep the urine inside the bladder until you are ready to urinate. When the bladder is full, the nerve endings between the cells stimulate and notify the brain that the body is ready to go "potty". ===

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 * [|Quiz] (click on Quiz for the quiz) **

A video on the urinary system! [] Bibliography [] [] [] [] []

Uncover the Human Body by Luann Colombo