U7. Human nutrition

Question 1

Define ingestion

Answer 1

the taking in of substances such as food and drink into the body

Question 2

Define physical digestion

Answer 2

the breakdown of food into smaller pieces without chemical changes to the food molecules and making them small by making them

Question 3

Define peristalsis

Answer 3

wave of muscle alternate contraction that pushes food down the alimentary canal

Question 4

Define chemical digestion

Answer 4

breakdown of large insoluble molecules to small soluble molecules using enzymes

Question 5

Define absorption

Answer 5

movement of nutrients through the wall of the intestines into the blood

Question 6

Define assimilation

Answer 6

the uptake and use of nutrients by cells or becoming part of the cells

Question 7

Define egestion

Answer 7

the removal of undigested food from the body as faeces

Question 8

Describe mouth’s function

Answer 8

• ingestion takes place
• teeth break down food by mechanical digestion
• tongue rolls food into a ball and push it down the esophagus

Question 9

Describe salivary gland’s function

Answer 9

• produce saliva containing mucus and amylase
• mucus: helps food pass along smoothly, prevents enzymes from attacking alimentary canal
• amylase: chemical digestion of starch -> maltose

Question 10

Describe oesophagus’s functions

Answer 10

• peristalsis

Question 11

Describe stomach’s functions

Answer 11

• churning: mechanical digestion of food into smaller pieces
• pepsin: enzyme which breaks down proteins -> peptides
• hydrochloric acid: provides optimum pH2 for pepsin

Question 12

Describe liver’s functions

Answer 12

• produces bile
• converts excess glucose to glycogen using insulin for storage
• assimilation: amino acids to proteins as enzymes, fatty acids and glycerol to cholesterol for storage
• excess amino acids are deaminated (amino part -> ammonia -> urea), carboxyl part -> fats

Question 13

Describe gallbladder’s functions

Answer 13

• bile is stored

- released into duodenum through bile duct

Question 14

Describe pancreas’ function

Answer 14

• produces enzymes (includes: trypsin, amylase, lipase)

Question 15

Describe duodenum’s function

Answer 15

• content from the stomach is mixed with bile, pancreatic enzymes
• chemical digestion: starch -> maltose, proteins -> peptides, fats -> fatty acids and glycerol

Question 16

Describe ileum’s functions

Answer 16

• more digestion: maltose -> glucose, peptides -> amino acids, lipids -> fatty acids & glycerol
• villi structure for absorption of small food substances (glucose, amino acids through blood vessels, glycerol&fatty acids through lacteal)

Question 17

Describe how a villi is adapted for absorption

Answer 17

• large surface area
• epithelium cell only one cell thick
• microvilli to increase surface area
• lots of mitochondria in the epithelial cells for active taransport

Question 18

Describe the colon’s function

Answer 18

absorption of excess water

Question 19

Describe the rectum’s function

Answer 19

store faeces temporarily

Question 20

Describe the anus’ function

Answer 20

an opening which allows egestion to take place

Question 21

Name the four kinds of teeth, shape and function

Answer 21

• incisors: cutting, chisel shaped
• canine: tearing, pointed
• premolar: grinding and chewing, have cusps
• molar: grinding and chewing, have cusps

Question 22

explain how tooth decay happens

Answer 22

• bacteria and sugar coat on the tooth to form a plague
• bacteria uses sugar for respiration, producing acid
• acid dissolves the enamel, later the dentine, then into the pulp cavity, causing immense pain

Question 23

What is the importance of bile in digestion?

Answer 23

Bile emulsifies large fat molecules into small droplets to increase surface area for enzyme actions

Question 24

What is the importance of stomach in digestion?

Answer 24

The stomach churns, digesting food physically, and mix food with digestive juice which contains enzymes an acid so it can break down into smaller, digestible pieces