28 - Excretion Removing Metabolic Waste Excretory System 28 - Excretion Excretion: Removing Metabolic Waste Do Now – Name as many wastes as you can that must leave the body in order to be healthy Introductory Biology by Charles M. Zaremba © 2003, published by TEACHINGpoint

EXCRETORY SYSTEM FUNCTION To remove waste from the body. It includes the SKIN, LIVER, KIDNEYS, and LUNGS. The SKIN removes heat from the body by releasing SWEAT which evaporates and cools our body. The skin also removes some of the same substances as urine including urea and salts.

Regents Question Which human excretory structure aids in the maintenance of normal body temperature? 1)Urinary bladder 2)Nephrons 3)Liver 4)Sweat glands

Regents Answer 4)Sweat glands

What is Cellular Waste? Cellular waste is one of the products of cellular metabolism. These materials are: excess water and salts, carbon dioxide, and urea. They must be eliminated from the organism or they can lead to its death.

Cellular Waste When carbon dioxide builds up in the blood, the brain signals the lungs to inhale and exhale. Carbon dioxide, a little water vapor and heat are removed as waste products by the lungs.

The Urinary Tract The renal artery brings oxygen rich, ‘dirty’ blood to the kidneys. The kidneys remove toxins, waste and excess water from the blood. The urine is sent from the kidney through the ureters to the bladder where it leaves the body through the urethra.

Regents Question Which sequence represents the correct pathway for the removal of urine from the human body? 1)Kidney-ureter-urinary bladder-urethra 2)Kidney-uretra-urinary bladder-ureter 3)ureter-kidney-urinary bladder-urethra 4)urethra-kidney-urinary bladder-ureter

Regents Answer 1)Kidney-ureter-urinary bladder-urethra

Ascending Loop Glomenulus Descending Loop Bowman Capsule

The Kidney The kidney is an excretory organ composed of many working units called nephrons. Each nephron will filter the organisms blood and concentrate the cellular waste for removal. The nephrons filter the blood and send the Urine to the ureters to the bladder where it is excreted via the urethra.

How the Nephron Works Bowman’s Capsule & Loop of Henle The capsule will take out water, amino acids, glucose, salts, and urea. The Loop of Henle will reabsorb the amino acids, glucose and, salt. (makes urine concentrated) Ascending Loop Glomenulus Descending Loop Bowman Capsule http://video.about.com/surgery/Kidney-Transplant.htm

Regents Question In humans, which substance is normally excreted through both alveoli and nephrons? 1)Water 2)Ammonia 3)Glucose 4)Uric acid

Regents Answer 1)Water

The Liver The liver makes bile to emulsify fats. The liver filters the blood to remove the dead red blood cells The liver makes digestive enzymes. The liver makes some amino acids The liver removes toxic ammonia by turning it into urea and excreted as part of the urine.

Elimination from the Body The concentrated urine will be dumped into the collecting tubules of the kidney. Each kidney will pass the urine to a large muscular organ called the urinary bladder via tubes called ureters. The Bladder will eliminate the urine from the body via a tube called the urethra.

The Large Intestine Undigested food in a solid form passes to the large intestine Water is reabsorbed into the body from the undigested material Solid waste is stored until it is excreted from the body.

Summary of the Excretory System Video Clip