Topic 2 digestion (from 2.27)

Question 1

What is the purpose of digestion?

Answer 1

Break down large insoluble molecules of food into small soluble molecules for absorption into bloodstream

Question 2

What is mechanical digestion and where does it occur?

Answer 2

• physically breaking down food

- chewing, churning etc. in mouth, stomach

Question 3

What is chemical digestion and where does it occur?

Answer 3

• enzymes

- mouth, stomach and small intestines

Question 4

What is the alimentary canal?

Answer 4

Channel through which food flows through body from mouth to anus

Question 5

What is the function of the mouth?

Answer 5

• mechanical digestion - teeth chew food to break it down

- amylase enzymes in saliva digest starch into maltose

Question 6

What is the function of the oesophagus?

Answer 6

• muscular tube to move food to stomach

- via peristalsis

Question 7

What is the function of the stomach?

Answer 7

• mechanically digested by churning actions
• chemically digested by protease enzymes which break down proteins into amino acids
• hydrochloric acid is present to provide optimum pH and kill bacteria
• ph 2

Question 8

What is the function of the pancreas?

Answer 8

• produces the digestive enzymes (amylase, protease and lipase)

Question 9

What is the function of the small intestine (duodenum) ?

Answer 9

• to mainly digest but also absorb broken down food molecules
• duodenum = first section of small intestine
• > where food finishes being digested by enzymes secreted from the pancreas and intestine walls
• > bile is released in the duodenum
  - bile = made in liver + stored = gall bladder
• bile emulsifies fats providing a larger surface area on which lipase can act (so digestion more efficient)
• also neutralise stomach acid

Question 10

What is the function of the ileum?

Answer 10

• second section of small intestine
• where absorption of digested food molecules takes place
• contains lots of white blood cells + important in immune response
• long and lined with villi to increase the surface area over which absorption can occur

Question 11

What is the function of the large intestine?

Answer 11

• water absorbed from remaining food in colon to produce faeces
• faeces stored in rectum + removed through anus

Question 12

What is peristalsis?

Answer 12

Contraction of muscle in intestine wall behind bolus that pushes bolus through

Question 13

What organ produces bile?

Answer 13

Liver

Question 14

Where is bile stored?

Answer 14

Gall bladder

Question 15

What is egestion

Answer 15

Where food that is unable to be absorbed leaves alimentary canal as faeces

Question 16

Where is amylase located and what does it do?

Answer 16

• salivary glands/pancreas

- breaks down starch to maltose

Question 17

Where is maltase located and what does it do?

Answer 17

• small intestine

- breaks down maltose to glucose

Question 18

Where is protease located and what does it do?

Answer 18

• stomach/pancreas

- breaks down protein to amino acids

Question 19

Where is lipase located and what does it do?

Answer 19

• pancreas
• acts in duodenum
• breaks down lipids into fatty acids and glycerol

Question 20

What is an enzyme?

Answer 20

Speeds up reaction without being used itself

Biological catalyst

Question 21

What is the pH of the mouth?

Answer 21

6.5

Question 22

What is the pH of the stomach?

Answer 22

2

Question 23

What is the pH of the duodenum?

Answer 23

7.5

Question 24

What is assimilation?

Answer 24

• movement of digested food molecules into cells and processing/storing them
• the liver is important as stores some of glucose absorbed as glycogen
• also converts some of absorbed amino acids into useful proteins

Question 25

How is the small intestine adapted for absorption?

Answer 25

• has lots of villi

- increases surface area so molecules can enter bloodstream quickly

Question 26

How does a villus’ structure relate to its function?

Answer 26

1. Villi give ileum large sa -> absorption
2. Cells w microvilli increase sa for active transport / diffusion
3. Large capillary network -> blood supply that constantly carries absorbed products away (maintains concentration gradient for fast diffusion)
4. Lipids are absorbed into lacteal to go to lymphatic system
5. Epithelium (wall) thin -> decreases diffusion distance

Question 27

What is absorption?

Answer 27

Absorption is the movement of small digested food molecules from the digestive system into the blood (glucose and amino acids) and lymph (fatty acids and glycerol)