Excretory System Functions Remove liquid waste...what is this waste called? Maintain water balance Regulate blood pH Composition of Urine Water Urea Produced when amino acids are burned for energy Uric acid, salts and ammonia Minerals, vitamins and heavy metals

KIDNEY VIDEO vakidney.mov

Excretory System Anatomy and Function Skin excretes excess water, salts and a small amount of urea in the form of sweat Majority of work is done by the kidneys Renal Artery Right Kidney Left Kidney Ureters Abdominal Aorta Urinary Bladder

Excretory System Waste-filled blood from the body enters the kidney through the renal artery

Excretory System Inside the kidneys, nephrons filter out urea, excess water, amino acids, drugs and other waste products in the blood Filtered blood is returned to circulation via the renal vein Kidney Nephron

IV. The Nephron A. The kidney contains one million nephrons. B. The nephron is the functional unit of the kidney. Distal Tubule Glomerulus Arteriole Collecting Duct Proximal Tubule Capillary Nephron Movie

V. The formation of urine Filtration Blood from the renal arteriole enters the glomerulus The glomerulus has many large pores Blood pressure forces all the small molecules out of the blood stream into the proximal tubule. Blood cells, proteins and other large molecules stay in the blood. Glomerulus Arteriole Proximal Tubule

B. Reabsorption As the filtrate travels through the proximal tubule, most of the water, minerals, and all of the glucose is reabsorbed through the tubule wall back into the capillaries of the nephron. However, the tubule wall is impermeable to compounds containing nitrogen. *** What are these compounds? a. Urea, ammonia and uric acid Glomerulus Distal Tubule Arteriole Collecting Duct Proximal Tubule Capillary

C. Secretion As the filtrate travels through the distal tubule, excess H+ or NH+ are secreted into the filtrate. ***How does this help you? a. This regulates the body’s pH. 2. By the time the filtrate has reached the collecting duct it is now urine. Glomerulus Distal Tubule Arteriole Collecting Duct Proximal Tubule Capillary

VI. Ureters A. Urine leaves the kidneys and is carried to the urinary bladder by the ureters. VII. Urinary Bladder A. Stores urine B. When the bladder fills, stretch receptors stimulate the brain. C. The urge usually begins when the bladder has about 150 ml. D. At 600 ml you get severe pain which usually forces you to urinate. Urine testing: drugs are not recirculated in the blood they are passed out in urine Urethra Carries urine to the outside of the body (passes 1-2 L per day)

IX. Disorders of the urinary system A. Kidney Stones Calcium, Magnesium or uric salts in the urine crystallize and form kidney stones. These stones block the ureters causing pain. When the stones are passed out of the urethra, the pain can be very severe. Ultra sound is used to break them into smaller stones. Urine testing: drugs are not recirculated in the blood they are passed out in urine

Guinness Book of Medical World Records Most kidney stones produced As of April 16, 2003, Don Winfield of Caledonia, Ontario, Canada, has produced and passed an excruciating 4,504 kidney stones, ranging in size from a grain of sand to a dried pea. Eventually, the kidney had to be removed. "At its worst," says Don, "I produced 22 stones in 24 hours... and 35 over a period of five days." Urine testing: drugs are not recirculated in the blood they are passed out in urine

B. Urinary Tract Infection (UTI) 1. Caused by a bacterial infection of any part of the urinary tract…How is it treated? Kidney Failure 1. One or both kidneys are damaged by disease or injury 2. Treatment is renal dialysis or transplant Asparagus pee

Blood in tubing flows through dialysis fluid Blood pump Artery Used dialysis fluid Shunt Air detector Dialysis machine Fresh dialysis fluid Compressed air