Large intestine physiology

Question 1

What is the role of ion absorption in the large intestine

Answer 1

Sodium ions

Chloride ions

Question 2

Describe ways in which sodium ions can be absorbed

Answer 2

Sodium-hydrogen antiporter on the luminal membrane

Epithelial sodium channels

Enhanced by absorption of short-chain fatty acids in the colon via specialised symporters

Question 3

How is bicarbonate and chloride absorbed

Answer 3

Movement of sodium into plasma produces an electrochemical gradient to allow absorption of chloride

Chloride ions are exchanged for bicarbonate ions - causing net bicarbonate secretion

Question 4

How is water absorbed

Answer 4

Absorption of electrolytes creates an osmotic gradient to allow further absorption of water

Question 5

How is potassium absorbed

Answer 5

Electrochemical gradient for the movement if potassium into the plasma

Question 6

What vitamins are absorbed in the terminal ileum

Answer 6

ADEK

B12

Question 7

What vitamins are absorbed in the terminal jejunum

Answer 7

B
C

Question 8

What % of bile acids are reabsorbed in the ileum

Answer 8

97%

Question 9

What % of bile salts continue into the colon

Answer 9

3%