3.1.2 (digestion) - part 1

Question 1

The gastrointestinal tract/process of digestion

Answer 1

1. Mouth
2. Salivary glands
3. Tongue
4. Oesophagus
5. Stomach
6. Liver
7. Gall bladder
8. Small intestine
9. Colon
10. Rectum
11. Anus

Question 2

1. Mouth

Answer 2

Digestion begins here (bite + chew feed = broken down into smaller particles, forming bolus).

Question 3

2. Salivary glands

Answer 3

Food is moistened with saliva = becomes bolus, making it easier to swallow.

Question 4

3. Tongue

Answer 4

Tongue pushes bolus into pharynx for swallowing.

Question 5

4. Oesophagus

Answer 5

Bolus enters through sphincter, peristalsis massages the bolus into the stomach, through another sphincter.

Question 6

5. Stomach

Answer 6

Peristalsis creates a churning action in the stomach. Bolus becomes paste known as chyme which stomach intermittently released into small intestine.

Question 7

6. Liver

Answer 7

Produces bile

Question 8

7. Gall bladder

Answer 8

Stores + releases bile into small intestine.

Question 9

8. Small intestine

Answer 9

Peristalsis pushes chyme through small intestine, bile breaks down fats into fatty acids + glycerol.

Question 10

9. Colon/large intestine

Answer 10

Peristalsis pushes chyme through large intestine, remaining water is gathered including indigestible fibres.

Question 11

10. Rectume

Answer 11

Waste is released (internal/involuntary + external/voluntary sphincters).

Question 12

11. Anus

Answer 12

Waste is expelled

Question 13

Carbohydrates - digestion
- Starts in the mouth

Answer 13

• CHO broken down into simple sugars by salivary amylase.
• Salivary amylase begins to break polysaccharides + disaccharides into dextrins + monosaccharides.

Question 14

Carbohydrates - digestion
- Small intestine

Answer 14

• Enzymatic hydrolysis occurs + CHO are broken down into simple sugars by enzymes such as pancreatic amylase.
• Enzymatic hydrolysis completes the breakdown of CHO into simple sugars, glucose, fructose, and/or galactose.
  *** fibre is undigestible + is used to add bulk to bowel.

Question 15

Carbohydrates - absorption

Answer 15

Occurs in the duodenum (first section of small intestine).
- Villi + microvilli projections absorb glucose through their outer single cell wall into blood capillaries + then into bloodstream.
- Cells lining the SI absorb glucose into blood capillaries, then into bloodstream via veins + arteries.

Question 16

Carbohydrates - utilisation

Answer 16

• Body uses CHO as a primary energy source.
• Any CHP not used in the body can be converted to glycogen + stored in liver or muscle tissue.