Nutritions in Humans

Question 1

Why is digestion important?

Answer 1

1. breaks down larger molecules into smaller, simpler soluble and diffusible molecules
2. can be absorbed into the blood stream and transported to body cells to be utilised

Question 2

Define physical digestion, its purpose, where in the alimentary canal it can be found.

Answer 2

1. mechanical breakdown of food into smaller pieces
2. increases the SA:V ration for digestive enzymes to act on food efficiently

Mouth and Stomach

Question 3

Define chemical digestion

Answer 3

1. enzymatuc reaction that breaks down large molecules to smaller, diffusible ones.

*digestive enzymes are released in mouth, stomach and SI

Question 4

Tell me the pathway of food! (Hint: its not the pathway of the alimentary canal)

Answer 4

Ingestion - Digestion - Absorption - Assimilation - Egestion

Question 5

What is digestion

Answer 5

the process where food is broken down from larger molecules into smaller, simpler soluble and diffusible molecules that can be absorbed by bodily cells

Question 5

What is ingestion?

Answer 5

the intake of food

Question 6

What is assimiliation?

Answer 6

digested food is converted into new protoplasm/used to provide energy

Question 7

What is absorption

Answer 7

digested food diffuses into cells

Question 8

3 enzymes and what reactions they catalyse:
1. lipases
2. amylase
3. proteases

Answer 8

1. (fat digesting) Fat –(lipase)–> glycerol+fatty acid
2. (starch digesting). starch – (amylase) –>sugars/maltose
3. (protein digesting). Protein – (proteases)–> amino acids

Question 8

What is egestion?

Answer 8

discharge of undigested materual

Question 9

What occurs in moth/buccal cavity?

Answer 9

Physical digestion:
- When food enters the moth, teeth breaks up food into smaller pieces
- increase in SA:V ration for enzymatic action on food chewing
- muscular tongue mixes food with saliva and rolls it into compact masses called bolus
- push bolus to back of the moth where its swallowed

Question 10

What is the purpose of salivary glands?

Answer 10

produces saliva which contains enzymes. flows into buccal cavity via sulivary duct.

SALIVARY AMYLASE:
hydrolyses starch -> maltose

LYSOZYME
1. kills bacteria, microorganism
2. is present in mucus - soften and lubricates food making swallowing easier

Question 11

talk about the swallong process.

Answer 11

1. food is pushed into the pharnyx (connects moth or gullet and larynx -> voice box)
2. Epiglottis (small flap) is bent down because weight of food. windpipe is closed.

Question 12

Function of oesaphagus

Answer 12

Movement through peristalsis.

Question 13

define peristalsis and its functions.

Answer 13

Peristalsis is the rhythmic contractions of circular and longitudinal muscles along the digestive system that propels food in a wave-like, unidirectional motion that is independent of gravity. involves a pair of antagonistic muscles which alternate in contraction.