The Excretory System

1. The Excretory System

2. STRUCTURES • Kidneys – filter blood of wastes • Ureter – tube leading to bladder • Urinary bladder – smooth muscle bag that stores urine

4. Specifics… • KIDNEY • Nephrons – filtering unit of kidney. • Blood enters nephron carrying wastes. • Blood travels into the capillaries of the nephron called the glomerulus • In the nephron, under high pressure, water, glucose, vitamins, amino acids, protein wastes, salts, and ions from the blood pass out of the blood into a part of the nephron called the Bowman’s capsule.

5. Glomerulus Bowman’s capsule Nephron Kidney

6. Specifics… • Bowman’s capsule – part of nephron • As liquid passes into the capsule it passes through a narrow, U-shaped tubule that reabsorbs water, glucose, and amino acids. Water also diffused back into the blood capillaries.

7. Formation of urine! • Urine – liquid that remains in the tubule: composed of excess water, waste molecules, and excess ions • YOU PRODUCE ABOUT 2L OF URINE PER DAY!!!

8. Waste flows out of the kidneys, through the ureter into the urinary bladder, and out of the body through a tube called the urethra.

10. Urinary System and Homeostasis • Major waste products – ammonia and urea • THESE ARE TOXIC TO THE BODY! • Kidneys control level of sodium in blood by removing and reabsorbing sodium. • Kidneys regulate pH of blood as well.

11. Urine Regulation • Hypothalamus - small part of brain that controls many body processes • Produces hormone ADH (antidiuretic hormone) that stimulates reabsorption of water in a nephron.