1. Excretory System Notes

2. Excretory System
Function: maintain homeostasis by removing waste materials from the body
Every cell produces metabolic wastes (waste products from chemical reactions).
Excretion: process of removing wastes from the body

3. Excretory System
The skin excretes excess water and salts in the form of sweat.
The lungs excrete carbon dioxide.
The kidneys play a major role in excretion.

4. Excretory System Kidney Function:
Remove nitrogenous waste from blood (pee pee)
Maintain blood pH
Regulate water content of the blood

5. Nitrogenous Waste
When protein is broken down, excess amino acids are released into the blood
Proteins are made of amino acids, which have nitrogen in them
The liver uses some amino acids to make useful compounds but some waste nitrogen is converted into urea (in mammals), which is the major part of urine

6. -Human kidneys are a pair of bean-shaped organs about 10 cm ( 4 inches) long.
-Blood enters each kidney via the renal artery and exits via the renal vein.
E life 32.2

7. -About 20% of the blood pumped by EACH heartbeat passes through the kidneys.

8. Structure Label your diagram: A kidney has two distinct regions:
Renal medulla – inside part
Renal cortex – outer part

9. Nephrons – the parts of the kidneys that filter out toxic substances from blood

10. How is blood purified? Filtration: Label your diagram:
Blood is filtered in a network of capillaries called the glomerulus
The glomerulus is located in a cup-shaped structure called Bowman’s capsule
Label your diagram:

11. Materials filtered out of the blood include small molecules like water, urea, glucose, salts, amino acids, and some vitamins.
Proteins, cells, and platelets remain in the blood because they are too large to pass through the capillary walls.

12. Reabsorption:
Almost 99% of the water is reabsorbed back into the blood at the
Loop of Henle – section of nephron involved in water reabsorption
Material that remains is urine
Label your
diagram

13. Elimination of Urine:
Ureter – carries urine to urinary bladder
Urinary bladder – saclike organ where urine is stored before being excreted

14. -Urine leaves the body from the urinary bladder through the urethra.
Sphincter muscles near the junction of the urethra and bladder control urination.

15. The hormone that causes the kidneys to reabsorb water is
Kidney function is controlled by water intake and hormones (increase water intake = increased excretion)
The hormone that causes the kidneys to reabsorb water is
Antidiuretic hormone

16. Kidney Disorders
Humans have two kidneys, but can survive with only one.
If both kidneys are damaged there are two options:
kidney transplant
kidney dialysis
Dialysis can take several hours a day & up to 3 times a week.