Intestinal Fluid And Electrolyte Transport

Question 1

What is the major site for Na+ absorption in the small intestine?

Answer 1

Jejunum

Question 2

List the different sodium pumps on the apical side in the jejunum.

Answer 2

1) Na+/monosaccharide cotransporter
2) Na+/amino acid cotransporter
3) Na+/H+ exchanger

Question 3

In the jejunum there is net absorption of what?

Answer 3

NaHCO3

Question 4

In the Ileum there is net absorption of what?

Answer 4

NaCl

Question 5

What does the colon absorb and secrete?

Answer 5

Absorbs Na
Secretes K
(Both through channels)

Question 6

Synthesis of the Na+ channels in the colon is induced by what?

Answer 6

Aldosterone

Question 7

Explain the effects of Cholera on crypts cells

Answer 7

Binds to basolateral receptor activating adenylyl cyclase/cAMP which opens Cl- on the apical membrane, causing water and Na to follow. Normally the villi cells will absorb this but when cholera maximally stimulates this it causes severe diarrhea

Question 8

Diarrhea causes loss of a lot of HCO3-. This will cause what type of metabolic condition.

Answer 8

• Hyperchloremic metabolic acidosis with normal anion gap

- Hypokalemia

Question 9

How does Lactase deficiency cause osmotic diarrhea?

Answer 9

Lactose is not digested into glucose and galactose which means it can’t be absorbed so it retains water.

Question 10

Where are the tight junctions “tighter”, allowing less paracellular movement?

Answer 10

Colon