CH5: Nutrition in Humans

Question 1

What is nutrition?

Answer 1

Nutrition is the process by which organisms obtain food and energy for growth, repair and maintenance of the body.

Question 2

Describe the sequence of processes that take place in humans in order to obtain nutrition.

Answer 2

1. Ingestion
2. Digestion
3. Absorption + Egestion
4. Assimilation

Question 3

Define ‘digestion’

Answer 3

the catabolic process of breaking down food into molecules that are soluble and small enough to be absorbed by the body

Question 4

Define ‘absorption’

Answer 4

the uptake of useful substances into the cells or the blood of the body

Question 5

Define ‘assimilation’

Answer 5

the use of products of digestion by various cells and tissues or to be part of the body

Question 6

Describe the structure of the alimentary canal

Answer 6

• 9 metre
• long muscular tract
• extends from the mouth to anus

Question 7

Why must food be digested?

Answer 7

• food that humans eat is made up of complex organic compounds (e.g. carbs, fats and proteins)
• These macromolecules are too large to be absorbed by the cells and tissues in the body.
• digestion occurs to break down these complex molecules into simpler soluble molecules for absorption.

Question 8

Define ‘ingestion’

Answer 8

the act of taking food into the mouth

Question 9

Explain the physical digestion that takes place in the mouth.

Answer 9

1. Teeth + chewing breaks down food into smaller pieces > increases SA of foods > increases rate of chemical digestion by digestive enzymes
2. Salivary glands secrete saliva that moisten and softens food
3. Tongue mixes food with saliva + rolls food into bolus + moves food to the back of the mouth to swallow

Question 10

Explain the chemical digestion that takes place in the mouth.

Answer 10

The saliva secreted by the salivary glands contain salivary amylase that breaks down starch into maltose.