Physiology: Digestion & Absorption of Carbs, Proteins, Lipids, Calcium, Iron & Vitamins

Question 1

Give 2 examples of polysaccharides, oligosaccharides and monosaccharides.

Answer 1

-polysaccharides -> starch, glycogen -oligosaccharides -> sucrose, lactose -monosaccharides -> glucose, fructose

Question 2

What is the digestive process of oligosaccharides?

Answer 2

-oligosaccharide -> digested by amylase by intra luminal hydrolisis into oligosacchardies -> digested by enzymes e.g. lactase, maltase at brush border into absorbable monosaccharides

Question 3

Why can’t amylase break down starch/glycogen into monosaccharides?

Answer 3

-can’t break alpha terminal 1-4 links only interal alpha 1-4 links -can’t break alpha 1-6 links (branch links) or alpha 1-4 links beside branch links

Question 4

What mechanism transports glucose/galactose from lumen into cell and describe how this works?

Answer 4

-SGLT1 -Na2+ binds to SGLT1, this increases its affinity for glucose, glucose binds, both Na+ and glucose are transported into cell, Na+ dissociates, glucose affinity falls and so glucose dissociates

Question 5

What mediates fructose absorption from the lumen into the cell?

Answer 5

-mediated by facilitated diffusion by GLUT5

(facilitated diffusion is spontaneous movement of molecules across a membrane via transmembrane integral proteins, in this case GLUT5 is the integral protein, it binds along the way into the cell)

Question 6

What mediates fructose, glucose and galactose transport out of the cell?

Answer 6

mediated by facilitated diffusion by GLUT2

Question 7

protein now

Answer 7

idk