Nutrition: Digestion 2

Question 1

What are Proteins hydrolysed by?

Answer 1

Proteins are hydrolysed by enzymes called PEPTIDASES.

Question 2

Where is calcium absorbed?

What are the 2 cellular calcium transport proscesses?

Answer 2

Calcium is absorbed predominantly in the proximal small intestine.

1. Transcellular absorption (through the cell) stimulated by 1,25(OH)2D3
2. Paracellular absorption (passing through the intercellular space)

Question 3

Movement of calcium across the enterocyte involves 3 steps…..?

Answer 3

a) Entry via one of 2 calcium channels e.g. TRPV6
b) Intracellular diffusion aided by transport molecule CALBINDIN
c) Extrusion from the cell mediated mainly by Ca2+ ATPase on the basolateral border

Question 4

What regulates the Synthesis of CALBINDIN and TRPV6?

Answer 4

active form of Vit D

Question 5

Where iis 75% of the bodys iron found?

Answer 5

haemoglobin and myoglobin

Question 6

Where is dietary iron reduced and what does it form?

Answer 6

It is reduced in the GI tract to the ferrous form i.e. Fe2+ by ascorbate and a FERRIREDUCTASE enzyme located in the brush border of the enterocytes