Nutrition in Humans

Question 1

Describe the processes that nutrition consists of.

Answer 1

1. Ingestion: Food is taken into the body.
2. Digestion: Large food molecules are broken down into smaller, soluble molecules that can be absorbed into the body cells.
3. Absorption: Digested food substances are absorbed into the body cells.
4. Assimilation: Some of the absorbed food substances are converted into new protoplasm or used to provide energy.

Question 2

Name the accessory glands that are part of the digestive system.

Answer 2

1. Salivary glands
2. Pancreas
3. Liver
4. Gall bladder

Question 3

Teeth

Answer 3

Action: Chewing action.
Function: Break down large pieces of food into smaller pieces to increase the ESA of the food for enzymes to act on it more efficiently.

Question 4

Salivary glands

Answer 4

Action: Secrete saliva into the mouth.
Function:
Function: Moisten food and salivary amylase breaks down starch.

Question 5

Tongue

Answer 5

Action: shapes food into a bolus
Function: Easy for swallowing.

Question 6

Pharynx

Answer 6

Structure: Entry to the trachea and the oesophagus.
Function: Allows food to pass into the oesophagus.

Question 7

Epiglottis

Answer 7

Structure: Flap-like tissue
Function: Since the pharynx leads to both the trachea and the oesophagus, food may enter into the trachea when travelling down the pharynx. During swallowing, the epiglottis covers and blocks the entrance to the trachea (larynx) and leaves the entrance to the oesophagus open to allow food to pass into the oesophagus and not the trachea.

Question 8

Oesophagus

Answer 8

Structure: Narrow muscular tube, with longitudinal muscles in the outer side and circular muscles on the inside.
Function: Conduct food from the pharynx to the stomach via peristalsis.

Question 9

What is the purpose of hydrochloric acid present in the stomach?

Answer 9

1. Stops the action of salivary amylase by denaturing it.
2. Kills potentially harmful microorganisms in food.
3. Changes the inactive form of pepsinogen to the active form called pepsin.
4. Provides acidic medium for the action of pepsin.

Question 10

How is the small intestine adapted for absorption?

Answer 10

1. Greater SA of the small intestine.
2. Thin membrane (one cell thick) that separates the food substances from the blood capillaries.