chapter 7: human nutrition

Question 1

describe what is meant by a balanced diet

Answer 1

a diet consisting of all of the food groups in the correct proportions

Question 2

state the principal dietary sources

Answer 2

• carbs
• oils and fats
• proteins
• mineral ions
• vitamins
• fibre
• water

Question 3

describe the function of carbs

Answer 3

source of energy

Question 4

describe the function of oils and fats

Answer 4

insulation and energy store

Question 5

describe the function of proteins

Answer 5

growth and repair

Question 6

describe the function of mineral ions

Answer 6

used in small quantities to maintain health

Question 7

describe the function of vitamins

Answer 7

used in small quantities to maintain health

Question 8

describe the function of fibre

Answer 8

provides roughage for the intestine to push food through it

Question 9

describe the function of water

Answer 9

needed for chemical reactions to take place in cells

Question 10

describe the function of vitamin c

Answer 10

• forms an essential part of the collagen protein which makes up skin, hair, gums, and bones
• a lack of vitamin c causes scurvy which causes swelling, pain in the limbs and spontaneous bleeding

Question 11

describe the function of vitamin d

Answer 11

• helps the body to absorb calcium and so required for strong bones and teeth
• lack of vitamin d causes rickets which causes poor bone development

Question 12

describe the function of calcium

Answer 12

• needed for strong teeth and bones and involved in the clotting of blood
• lack of calcium can lead to osteoporosis

Question 13

describe the function of iron

Answer 13

• needed to make haemoglobin
• lack of iron cause anaemia

Question 14

describe the function of the mouth

Answer 14

• food is ingested here
• mechanical digestion of food

Question 15

describe the function of the salivary glands

Answer 15

• secretes saliva
• amyalse in saliva breaks down starch into maltose
• saliva makes food easy to swallow by lubricating it

Question 16

describe the function of oesophagus

Answer 16

• connects the mouth to the stomach
• peristalsis: contractions of the oeosphagus wall forcing the food downwards

Question 17

describe the function of the stomach

Answer 17

• mechanical digestion: churning of the muscular stomach walls
• protease enzymes break down proteins
• hydrochloric acid provides acidic pH environment for the enzymes and destroys pathogens

Question 18

describe the function of the liver

Answer 18

• produces bile which digests fat and neutralises the stomach acid as it exits the stomach

Question 19

describe the function of the gall bladder

Answer 19

• stores bile before it is released into the duodenum via the bile duct

Question 20

describe the function of the pancreas

Answer 20

• produces amylase, protease and lipase enzymes before they are released into the duodenum

Question 21

describe the function of the duodenum

Answer 21

• has an alkaline pH environment
• enzymes complete chemical digestion here

Question 22

describe the function of the ileum

Answer 22

• facilitates most absorption

Question 23

describe the function of the colon

Answer 23

• some more water is absorbed here
• solid waste left behind forms faeces

Question 24

describe the function of the rectum

Answer 24

• stores the faeces prior to egestion

Question 25

describe the function of the anus

Answer 25

- exit for faeces, egestion

Question 26

describe physical digestion

Answer 26

- breakdown of food into smaller pieces without chemical change to the food molecules - increases the surface area of food for the action of enzymes in chemical digestion

Question 27

describe the function of incisors

Answer 27

chisel shaped for biting and cutting

Question 28

describe the function of canines

Answer 28

pointed for tearing, holding and biting

Question 29

describe the function of premolars and molars

Answer 29

large flat surfaces with ridges for chewing and grinding

Question 30

describe the structure of a tooth

Answer 30

1. enamel: hard outer layer preotecting the tooth 2. dengine: layer beneath the enamel protecting the nerves 3. pulp: soft internal tissue containing nerves and blood vessels 4. cement: hard layer around the root of a tooth helping to anchor it within the jaw

Question 31

describe chemical digestion

Answer 31

- breaking down large insoluble molecules into smaller soluble molecules

Question 32

where does maltase act?

Answer 32

it breaks down maltose to glucose on the membranes of the epithelium lining the small intestine

Question 33

what is the difference between pepsin and trypsin?

Answer 33

- pepsin works in acicid conditions - trypsin works in alkaline conditions

Question 34

how is the ileum adapted for its function?

Answer 34

- very long and has a highly folded surface with millions of villi which massively increase the surface area of the ileum