Chapter 9.1 : Nutrition ( carbohydrates and proteins )

Question 1

What is the human digestive system made up of ?

Answer 1

A long and muscular alimentary canal that starts from
Mouth ——> Anus

Question 2

What does the alimentary canal consists of ?

Answer 2

Mouth , Oesophagus , Stomach , Small Intestine , Large Intestine , Anus

Question 3

Organs that are involved in the digestive system includes :

Answer 3

Liver , Gall bladder , Pancreas

Question 4

What digestive glands does the digestive system consists of ?
(glands) , (body part)

Answer 4

1. Salivary glands in the mouth
   2.Gastric glands in the stomach
   3.Intestinal glands in the ileum of the small intestine

Question 5

Definition of digestion :

Answer 5

Breakdown of large pieces of food into smaller pieces for easy absorption .

Question 6

Definition of physical digestion :

Answer 6

Breaking down of large food pieces by chewing into smaller pieces

Question 7

Uses of physical digestion :
What does it also involve ?

Answer 7

To increase the surface area of the food particles for an enzyme reaction.
Involve Peristalsis which moves the food particles down the alimentary canal.

Question 8

Definition of chemical digestion :
What does it also involve?

Answer 8

The decomposition process of complex molecules into simple molecules .
It also involves enzyme reactions .

Question 9

Where does the digestion of carbohydrate begins ?
What does it involve ?

Answer 9

Begins in the mouth .
Involves the salivary glands which secrete saliva 唾液 .

Question 10

What does saliva contain and its function :
Optimum pH for the enzyme to digest carbohydrate :

Answer 10

Saliva contains salivary amylase which hydrolyses starch to maltose .
pH 7

Question 11

Saliva helps food to form ____

Answer 11

Bolus .

Question 12

What happens to the epiglottis when swallowing? Why?f

Answer 12

The epiglottis will close the trachea opening to prevent food from entering the trachea .

Question 13

In the oesophagus , the bolus is moved by ______ .

Answer 13

Peristalsis .

Question 14

What is peristalsis ?

Answer 14

Peristalsis is the rhythmic contraction and relaxation of muscles along the alimentary canal .

Question 15

Where does the digestion of protein starts at ?

Answer 15

Starts at stomach

Question 16

The surface of the stomach wall is lined with _____

Answer 16

Epithelial cells to form gastric glands .

(Epithelial cells are a type of cell that covers the inside and outside of the surfaces of your body. They are found on your skin, blood vessels, and organs)

Question 17

What does gastric gland consists of ?

Answer 17

Chief cells , parietal cells . mucous cells

Question 18

What does chief cells secrete ?

Answer 18

Pepsinogen (inactive enzyme) .
Turns into pepsin by the acid in stomach .

Question 19

What does parietal cell secrete ?

Answer 19

Hydrochloric acid .

Question 20

What is mucous cell ?

Answer 20

Goblet cell .

Question 21

What does mucous cell secrete ?

Answer 21

Mucus .

Question 22

pepsin
Protein + water ————–> ?

Answer 22

Polypeptides .

Question 23

Salivary Amylase
Starch + water —————————-> ?

Answer 23

Maltose .

Question 24

What is pepsinogen ?

Answer 24

Pepsinogen is an inactive enzyme that is activated by hydrochloric acid to form pepsin .

Question 25

Function of pepsin :

Answer 25

Hydrolyses protein into polypeptides .

Question 26

Optimum pH for digestion of protein :

Answer 26

pH 2

Question 27

What does gastric juice contain ?

Answer 27

Hydrochloric acid , mucus and enzymes

Question 28

Function of hydrochloric acid :
activate ___

Answer 28

Activate inactive enzymes into active enzymes .
pepsinogen —-> pepsin

Question 29

Function of hydrochloric acid :
Provides ____

Answer 29

Provides an acidic medium for pepsin and rennin.

Question 30

Function of hydrochloric acid :
Kills ___

Answer 30

Kills bacteria .

Question 31

Function of hydrochloric acid :
Stops ___

Answer 31

Stops the action of salivary amylase . The digestion of starch stops as the pH is too low .

Question 32

Function of mucus :

Answer 32

Protects the walls of the stomach from being corroded by acid in the stomach .

Question 33

Function of pepsin :

Answer 33

Hydrolyses protein into peptones and polypeptides .

Question 34

Function of rennin :

Answer 34

Coagulates milk (solid—->liquid)
Converts caseinogen in mlik to casein . (soluble protein—->insoluble protein)

Question 35

Process of food in the digestion process of stomach :
(gastric juice , churned , peristalsis , chyme , sphincter muscle)

Answer 35

The food in the stomach is mixed with the gastric juice containing pepsin and hydrochloric acid . Food is churned by the peristalsis action of the stomach wall muscles for a few hours . The content in the stomach finally changes to a semifluid called chyme . Chyme enters the duodenum when the pyloric sphincter muscle relaxs .