B6.3 - digestion

Question 1

what are the different types of teeth?

Answer 1

incisor, canine, premolar and molar.

Question 2

Incisor: what is the position in the mouth, what is the description of the tooth and what is the function?

Answer 2

position: front
description: chiseled shape with sharp edge
function: biting off pieces of food

Question 3

Canine: what is the position in the mouth, what is the description of the tooth and what is the function?

Answer 3

position: either side of incisors
description: more pointed than incisors
function: biting off pieces of food

Question 4

Premolar: what is the position in the mouth, what is the description of the tooth and what is the function?

Answer 4

position: behind canines
description: have two point cusps, have one or two roots
function: tearing and grinding food

Question 5

Molar: what is the position in the mouth, what is the description of the tooth and what is the function?

Answer 5

position: back
description: have four or five cusps, have one or two roots
function: chewing and grinding food

Question 6

what are the different structures on a tooth?

Answer 6

Crown 
Gum
Root 
Enamel 
Cement 
Dentine 
Pulp cavity

Question 7

what is the CROWN (tooth structure)?

Answer 7

The crown is the part of the tooth which is visible above the gum line

Question 8

what is the GUM (tooth structure)?

Answer 8

The gum is the tissue which overlays the jaw

Question 9

what is the ROOT (tooth structure)?

Answer 9

This is the part of the tooth which is embedded in the jaw bone

Question 10

what is the ENAMEL (tooth structure)?

Answer 10

The surface of the crown is covered by a very hard layer

Question 11

what is the CEMENT (tooth structure)?

Answer 11

the cement enables the tooth to grip to its bony socket in the jaw

Question 12

what is the DENTINE (tooth structure)?

Answer 12

Is softer than the enamel and is the layer below the enamel.

Question 13

what is the PULP CAVITY (tooth structure)?

Answer 13

The pulp cavity contains nerves and blood vessels

Question 14

what are the different stages of dental decay?

Answer 14

1. Decay begins when small holes (cavities) appear in the enamel
2. These cavities are caused by bacteria on the tooth’s surface
3. The bacteria feeds on the sugars deposited on the teeth, respiring and producing acid which dissolves the calcium salts in the tooth enamel
4. The enamel dissolves away in patches, exposing the dentine layer to the acids
5. Since the dentine is softer than the enamel, it dissolves faster so cavities are formed
6. Cavities reduce the distance between the outside of the tooth and the nerve endings
7. The acids, which have been produced by the bacteria, irritate the nerve endings resulting in tooth ache

Question 15

what is the proper way to care for teeth?

Answer 15

• Best way to avoid tooth decay is to avoid eating sugar at frequent intervals
• Visit the dentist every 6 months for a check-up so any cavities or disease can be treated at an early stage
• Brushing teeth is very important in the prevention of gum disease
• Fluoride toothpaste helps reduce the bacterial population on the teeth and to increase their resistance to decay.

Question 16

what is the process of digestion?

Answer 16

digestion is a chemical process and consists of breaking down large molecules to small molecules.

The large molecules are usually not soluble in water, while the smaller ones are. The small molecules can be absorbed through the epithelium of the alimentary canal, through the walls of the blood vessels and into the blood.

Question 17

what are the different types of enzymes?

Answer 17

amylase, protease and lipase.

Question 18

what does amylase do?

Answer 18

breaks down starch to simple sugars

Question 19

what does protease do?

Answer 19

breaks down proteins to amino acids

Question 20

what does lipase do?

Answer 20

breaks down fats to fatty acids and glycerol

Question 21

what is the function of hydrochloric acid and gastric juice?

Answer 21

Hydrochloric acid is secreted by cells in the wall of the stomach and creates a very acid pH of 2.
The pH is important because it denatures enzymes in harmful organisms in food such as bacteria and it provides optimum pH for the protein digesting enzymes ‘pepsin’ to work. (protease enzymes)

Question 22

what is the pH level of hydrochloric acid?

Answer 22

2 - very acidic

Question 23

where is the protease enzyme located?

Answer 23

in the stomach

Question 24

what is the function of bile?

Answer 24

• Bile contains bile salts
• Bile salts emulsify fats.
• Emulsifying fats means they break them down into smaller droplets which can be efficiently digested by lipase.

Question 25

What is Villi and what is the function of it?

Answer 25

• Vill increase the surface area in the small intestine for absorption
• The structure: the villus is about 0.5mm long and may be finger-like or flattened in shape
• Membranes have microvilli which increase the surface area by 20 times.

Question 26

What are capillaries and what do they do in the digestive system?

Answer 26

• Capillaries are the small molecules of digested food
• For example, glucose and amino acids pass through the epithelial cells and then through the wall of the capillaries in the villus and into the bloodstream.
• They are then carried away in the capillaries, which join up to form veins

Question 27

what are lacteals and what do they do in the digestive system?

Answer 27

• Some of the fatty acids and glycerol from digestion of fats enter the blood capillaries of the villi
• A large proportion of the fatty acids and glycerol might be combined to form fats against the intestinal epithelium.
• These fats then pass into the lacteals
• The fluid in the lacteals flows in the lymphatic system, which forms a network all over the body and eventually empties its contents into the bloodstream.