2.10 Excretion

Question 1

What is excretion?

Answer 1

the removal from the body of the waste products of metabolism

Question 2

What are the two most significant toxic compounds?

Answer 2

carbon dioxide - dissolves to form a weakly acidic solution in blood and tissue fluid
urea - comes from excess amino acids and can denature enzymes

Question 3

Describe Ultrafiltration

Answer 3

• occurs between the Glomerulus and Bowmans capsule
• has a high blood pressure because the vessel going in is lager then the vessel going out
• capillaries have pores which allow small molecules to be forced to the Bowmans capsule
• salts, amino acids, urea, water and glucose form the filtrate inside the nephron
• proteins, red blood cells, white blood cells and platelets are left behind

Question 4

Describe Selective reabsorption

Answer 4

Returns all the useful molecules to the blood
- ALL glucose
- ALL amino acids
- most H2O
Happens via diffusion, active transport and osmosis
The micro villi infolding of cell membrane increase the surface area and the mitochondria respire providing ATP for active transport

Question 5

What happens in the Loop of Henle?

Answer 5

The medulla becomes salt lowering the water potential causing water to diffuse out of the blood via osmosis