3.1.2 (digestion) - part 2

Question 1

Protein - digestion
- Stomach

Answer 1

Chemical digestion of proteins start in the stomach.
- Stomach releases gastric acid containing hydrochloric acid (HA).
- Pepsin is released amongst the gastric juices.
- HA activates P which begins the breakdown of protein into amino acid (enzymatic hydrolysis).

Question 2

Protein - digestion
- small intestine

Answer 2

Pancreatic protease released from pancreas into SI where it breaks down the proteins further into amino acids + peptides.

Question 3

Protein - absorption

Answer 3

Occurs in the small intestine.
- Amino acids are moved from the villi to the bloodstream which then transports the amino acids to the cells in the body as needed.

Question 4

Protein - utilisation

Answer 4

• Body uses protein for growth, maintenance, + repair of body cells (eg. muscles, blood, connective tissues, etc).
• Protein assist in energy production.
• Secondary energy source for growth + activity.

Question 5

Fats - digestion
- Mouth

Answer 5

Lingual lipase is released by saliva but doesn’t begin to work until it reaches the stomach.

Question 6

Fats - digestion
- Stomach

Answer 6

Acid in the stomach activates lingual lipase, joined by gastric lipase released in the stomach, beginning fat digestions.

Question 7

Fats - digestion
- Liver

Answer 7

Liver releases bile that mixes with the chyme in the SI.
- Bile = digestive fluid produced by liver, stored in gall bladder, released into SI. Facilitates growth by acting as an emulsifier.
- Bile breaks down fat into smaller particles providing a larger surface area for digesting lipases.

Question 8

Fats - absorption

Answer 8

Fatty acids + glycerol are absorbed into villi of the SI + mix with lymphatic fluid.
- They move around the body in the lymphatic system, joining blood circulation as insoluble fats.

Question 9

Fats - utilisation

Answer 9

• Used for insulation + protection around vital organs.
• Helps transport fat-soluble vitamins.
• Used as a secondary energy source.
• Any fat not used by the body is stored as adipose tissue.