Chapter 15 (Homeostasis)

Question 1

What is the ornithene cycle?

Answer 1

The ornithene cycle is the process used to break down ammonia (NH3) into urea. Stages include:
1) NH3 and CO2 are added to ornithene, H2O is released and citruline is produced.
2) NH3 is added to citruline, H2O is released and arginine is produced.
3) H2O is added to arginine, urea is released and ornithene is produced.

Question 2

What are the main functions of the liver?

Answer 2

a) Carbohydrate metabolism- storage of glycogen and release of glucose.
b) Transamination- converting one amino acid into another
c) Deamination of excess amino acids- removal of amine group which is converted to ammonia, and the rest of the amino acid can be used in respiration or converted to lipids for storage.

Question 3

What is a hepatocyte and what are their main features?

Answer 3

Hepatocytes are also known as liver cells.
They have large nuclei, prominent Golgi apparatus and lots of mitochindria.

Question 4

In what order of structures does filtrate move through the kidney?

Answer 4

1) Afferent arteriole
2) Glomerulus
3) Bowmans capsule
4) Proximal convoluted tubule
5) Loop of Henle
6) Distal convoluted tubule
7) Collecting duct

It then moves into the pelvis, through the ureter and into the bladder

Question 5

What are the 3 main layers of the kidney, from outside to inside?

Answer 5

1) Capsule
2) Cortex
3) Medulla (Think middle)

Question 6

Why does water potential decrease further down the descending loop of Henle?

Answer 6

In the ascending loop, ions are actively pumped out. This causes the tissue fluid to have a lower water potential, so water moves out of the descending limb