14. Digestion & Absorption

Question 1

Explain movement of undigested carbohydrates

Answer 1

Into large intestine along with osmotic water load

May be fermented by intestinal bacteria, giving FA’s, alcohols and gases

Question 2

Explain absorption of hexoses in enterocytes

Answer 2

Glucose and galactose transported across brush border luminal membrane by SGLT1 powered by Na pump

Question 3

How is fructose transported into enterocytes?

Answer 3

Direct into enterocytes by GLUT5

Question 4

How are hexoses absorbed into circulation from enterocytes?

Answer 4

GLUT2 in basolateral membrane

Question 5

Explain what is meant by intermediate digestion of protein

Answer 5

Cooking;

Denaturation. Hydrolysis of peptide bonds by endo and exopeptidases to yield oligopeptides/AA’s

Question 6

Explain AA absorption into enterocyte

Answer 6

Cotransported with Na

Secondary AT, powered by basolateral Na pump

Question 7

Explain calcium absorption in the intestine

Answer 7

Via GI tract (100mg/day)

Absorbed along entire tract

Influenced by Vit D3

Question 8

Explain Vit B12 absorption

Answer 8

Combines with intrinsic factor

Brush border of ileum contains transporter for B12

Question 9

Explain iron absorption

Answer 9

Regulated by body levels and requirements