3 - Digestion and absorption

Question 1

Digestion in the mouth

Answer 1

Salivary amylase - starch to maltose - glycosidic bonds hydrolysed - only small amount of starch is broken due to short time food remains in mouth

Question 2

Digestion in the stomach

Answer 2

• Pepsin - endopeptidase
• Hydrochloric acid - optimum pH for enzymes / kills bacteria

Question 3

Digestion in the duodenum

Answer 3

• Bile produces in liver and stored in gall bladder
• Neutralised acid in stomach - alkaline conditions for for opt pH for pancreatic enzymes
• Bile salts - emulsify lipids - increase SA -Micelles formed

Question 4

Digestion in pancreatic juice

Answer 4

• amylase
• lipase
• endopeptidase
  -exopeptidase

Question 5

Digestion in ileum

Answer 5

-Dipeptidase
- Lipase
- Maltase
-Sucrase
-Lactase

Question 6

Absorption of amino acid/ glucose

Answer 6

1 - Na/k pump which actively transports Na out and K in - uses energy from ATP- Na conc low in epithelial cell
2 - Na/ glucose enters by co - transport
3 - Facilitated diffusion of glucose through glucose channel/carrier protein

Question 7

Absorption of lipids

Answer 7

• Micelles break up to glycerol and fatty acid which simply diffuse into epithelial cell
• IN SER - fats formed by condensation reactions
• Golgi processes triglycerides n joins with proteins to form chylomicrons which are packaged into vesicles
• vesicles fuse with membrane releasing chylomicrons which diffuse into lacteals- driains into bloodstream