32 4 Excretory System KEY CONCEPT The excretory

32. 4 Excretory System KEY CONCEPT The excretory system removes wastes and helps maintain homeostasis.

32. 4 Excretory System

32. 4 Excretory System The excretory system eliminates nonsolid wastes from the body. • Nonsolid wastes are eliminated through lungs, skin, and kidneys. • Lungs exhale carbon dioxide and water vapor. • Sweat glands in skin release excess water and salts. • Kidneys filter and clean the blood to produce urine. skin lungs kidneys ureters urethra urinary bladder

32. 4 Excretory System • Kidneys have three basic functions in maintaining homeostasis. – remove waste from blood – help to maintain electrolyte, p. H, and fluid balances – release key hormones

32. 4 Excretory System The kidneys help to maintain homeostasis by filtering the blood. cortex • Kidneys are a pair of beanshaped organs. – two layers: medulla and cortex – filtering units called nephrons – renal artery and renal vein medulla renal artery renal vein ureter (to bladder)

32. 4 Excretory System Nephrons clean the blood and produce urine. • 4. Glomerulus-filters and cleans the blood • 5. Bowman’s Capsule-holds the filtrate, molecules are reabsorbed into the capillaries to balance the blood from body chemically • 6. Loop of Henle. Water is reabsorbed. 7. Collecting ductscollect urine from to body nephrons and send it to the from other loop of Henle nephrons ureter.

32. 4 Excretory System Nephrons clean the blood and produce urine. • Nephrons are the filtering units in the kidneys. • They clean and rebalance the blood to produce urine. from body to body loop of Henle from other nephrons

32. 4 Excretory System • Nephrons clean the blood in a three-step process. • The first step is filtration of the blood. 1 FILTRATION Glomerulus Bowman’s capsule Water, electrolytes, aminoacids, glucose, urea, and other small molecules diffuse out of the blood, creating the filtrate.

32. 4 Excretory System • The first step is filtration of the blood. • The second step is reabsorption of materials. • The third step is excretion of materials. from body 2 REABSORPTION As the filtrate enters the rest of the tubule , most of the materials are reabsorbed into the blood. Materials not reabsorbed make up the urine, which flows into the loop of Henle. collecting duct to body loop of Henle from other nephrons 3 EXCRETION In the loop of Henle, water can be reabsorbed one final time to reduce the volume of urine. The remaining urine flows into a collecting duct that leads to the ureter.

32. 4 Excretory System Injury and disease can damage kidney functions. • A kidney transplant can replaced damaged kidney. – recipient and donor tissue must match – drugs prevent tissue rejection The daughter and son in this photo donated a kidney and liver tissue to their mother.

32. 4 Excretory System • Dialysis can be used to filter and clean the blood.

32. 4 Excretory System

32. 4 Excretory System Hand-in worksheet on the Excretory/Urinary System