Section 10 3 Your Excretory System Organs of

Section 10. 3 Your Excretory System Organs of Excretion • Excretion is the process by which the body collects and removes wastes. • Several organs in the body are involved in waste collection and removal • liver • lungs • skin • kidneys Slide 1 of 21

Section 10. 3 Your Excretory System Liver • The liver converts impurities and poisons in the body to less harmful substances. • The liver forms urea from a harmful waste product of protein breakdown. Slide 2 of 21

Section 10. 3 Your Excretory System Lungs and Skin • The lungs remove carbon dioxide and some water from the body. • Sweat glands in the skin serve an excretory function because water and urea are excreted in perspiration. Slide 3 of 21

Section 10. 3 Your Excretory System Kidneys • The kidneys, which are the major organs of the excretory system, filter urea and other wastes from the blood. • You have two kidneys, each about the size of a fist. • Urine is a watery fluid produced by the kidneys that contains urea and other wastes. Slide 4 of 21

Section 10. 3 Your Excretory System The Excretory System Kidney The kidneys produce urine by filtering urea and other wastes from the blood. Ureter One ureter extends from each kidney. The ureters carry urine from the kidneys to the bladder. Bladder The bladder is a saclike muscular organ that stores urine. Urethra Urine travels through the urethra as it exits the body. Slide 5 of 21

Section 10. 3 Your Excretory System Filtration of Wastes • Each kidney contains about a million nephrons, tiny filtering units that remove wastes and produce urine. • The nephrons filter wastes in stages. • Needed materials and wastes are filtered from the blood. • Most needed materials are returned to the blood, and the wastes are eliminated from the body. Slide 6 of 21

Section 10. 3 Your Excretory System Filtering Out Wastes • Blood enters the kidneys. • Blood flows through smaller blood vessels until it reaches a cluster of tiny blood vessels in a nephron called a glomerulus (gloh MUR yoo lus). • Urea, salts, glucose, and water are filtered from the glomerulus into a thin-walled capsule. Slide 7 of 21

Section 10. 3 Your Excretory System Formation of Urine • As the filtered material flows through the tube, the glucose, most of the water, and other needed materials pass from the tube back into the blood. • Urea and other wastes, such as excess vitamins and harmful substances, stay in the tube. Slide 8 of 21

Section 10. 3 Your Excretory System A Nephron Blood flows from an artery into a nephron. In the glomerulus, urea, water, glucose, and other materials are filtered from the blood. These materials pass into a capsule that surrounds the glomerulus. The materials pass from the capsule into a long, twisting tube. The tube is surrounded by blood vessels. As the filtered material flows through the tube, most of the water and glucose are reabsorbed into the blood. Most of the urea and other waste stay in the tube. After the reabsorbing process is complete, the liquid that remains in the tube is called urine. Slide 9 of 21

Section 10. 3 Your Excretory System Vocabulary excretion The process by which the body collects and removes wastes. urea A substance formed in the liver from a waste product of protein breakdown. kidney A major organ of excretion that filters wastes from the blood and produces urine A watery fluid containing urea and wastes that is excreted from the body. Slide 10 of 21

Section 10. 3 Your Excretory System Vocabulary nephron A tiny filtering unit in the kidney that removes wastes and produces urine. glomerulus A cluster of tiny blood vessels in a nephron. dialysis A treatment for kidney failure in which a machine is used to filter wastes from blood. Slide 11 of 21