Digestion

Question 1

Digestion

Answer 1

Breakdown of food
In mouth, stomach, duodenum
Chemical, mechanical

Question 2

Chemical digestion

Answer 2

In stomach, small intestine with enzymes

Question 3

Mechanical digestion

Answer 3

Mastication with teeth

Question 4

Ingestion

Answer 4

In mouth

Question 5

Egestion and excretion

Answer 5

Removal of waster food

Removal of metabolic waste

Question 6

Purpose of alimentary canal

Answer 6

Breakdown of large insoluble molecules to small soluble molecules
Small soluble molecules absorbed across gut wall into blood stream

Question 7

Pathway of carbohydrates

Answer 7

Respiratory pathway can only break down glucose to release energy
salivary amylase breaks down starch into maltose
Mastication in mouth
Bolus swallowed, small soft ball
Amylase denatured by hydrochloric acid
Amylase secreted by pancreas in small intestine
Small intestine small lining secretes maltase in cell surface membrane
Hydrolysed maltose into glucose, breaks glycosidic bonds
Disaccharase, sucrase, lactase found here

Question 8

Purpose of villi and microvilli

Answer 8

Villi, folding of intestinal wall
Microvilli, folding of membrane
Increase SA
Short distance for diffusion
Conc grad maintained with blood flow

Question 9

Protein digestion

Answer 9

Endopeptidase hydrolyses peptide bonds within protein
Optimum pH=low
Partially digested protein passes into small intestine
Bile neutralises mixture for enzyme function
Pancreatic juices contain endopeptidase, exopeptidase
Exopeptidase hydrolyses near end of polypeptide chains, dipeptides
Dipeptidase hydrolyses dipeptides, releases amino acids, released from cell surface membrane
Amino acid released into cytoplasm of cell, into blood by fac diff+cotransport

Question 10

Why use endopeptidase and exopeptidase

Answer 10

Endo hydrolyses peptide bonds within protein, creating more chain ends of polypeptide
Exo can hydrolyse more peptide bonds near end of chain, more available for breakdown

Question 11

Lipid breakdown

Answer 11

Only in small intestine lumen
Bile emulsifies fat droplets, bile salts bind to droplets, break down into smaller droplets
Physical process that increases SA for lipase
Lipase secreted by pancreas in small intestines, hydrolyses lipids into fatty acids and glycerol
Absorbed into cells after micelles break down into monoglycerides and fatty acids
Diffuse and synthesised into triglyceride in SER
Packed into chylomicrons, enter lacteals

Question 12

Absorption

Answer 12

VOlume absorbed over set period of time