L1 Physiology Of Chewing

Question 1

Incisor teeth are used for

Answer 1

Tearing and cutting

Question 2

Molar teeth are used for

Answer 2

Grinding and chewing

Question 3

Define mastication

Answer 3

The mechanical process of breaking down food into smaller portions and at the same time mixing it with saliva.

Question 4

What is the use of mastication?

Answer 4

It prepares food for swallowing

Question 5

What are some of the actions that happen in mastication?

Answer 5

Cutting and tearing
Grinding and chewing
Chopping and squashing
The food between the upper and lower teeth

Question 6

Is mastication voluntary or involuntary?

Answer 6

It is mainly a voluntary process but it is coordinated by reflex activities like the chewing reflex.

Chewing has both voluntary and involuntary components. A single bite is a voluntary process. Chewing is a programmed pattern of movements organized at a low level in the central nervous system.

Question 7

List the steps of mastication

Answer 7

1. You have a bolus of food in your mouth
2. Tactile recpetors in the mouth are stimulated (innate receptors even in newborns)
3. Reflex inhibition from the muscles of mastication
4. Lower jaw drops/contracts, stretching of temporalis muscle
5. Rebound contraction, Lower jaw pushes up producing tactile pressure
6. Repeat cycle

Question 8

What are the 3 salivary glands, their cell types, and the location of their ducts?

Answer 8

1. Parotid (Serous cells) (near second upper molars)
2. Submandibular (SEROUS + mucous cells) (near frenulum of the tongue)
3. Sublingual (MUCOUS + serous cells) (at the floor of the mouth)

Question 9

What do serous secretions contain and what at what pH is it active?

Answer 9

• contain ptyalin, a type of alpha-amylase
• enables digestion of carbs
• active between pH 4-11 but optimal activity at pH 7

Question 10

What do mucous secretions contain?

Answer 10

• mucin, a glycoprotein for lubrication of food and mouth

- helps in swallowing, speech, protection of inner lining of the mouth

Question 11

How much saliva do we secrete daily and what is it controlled by?

Answer 11

800 - 1500 ml

It is controlled by the amount of blood flow because it controls salivary flow.

Question 12

What are the functions of saliva?

Answer 12

1. Moisten mouth and help speech
2. Lubrication: assist swallowing
   3.Helps taste buds: dissolves food molecules
3. Initiates digestion of starch (alpha-amylase)
   5.Buffering: contains bicarbonate (against stomach acid), phosphate, and mucin
4. Oral hygiene
   A. Washes away pathogenic bacteria
   B. Destroy bacteria through thiocyanate ions and lysozyme
   C. Protein antibodies destroy oral bacteria + protect against dental caries

Question 13

What is the structure of salivary glands?
A. List the different cells
B. Describe the path of flow of secretions

Answer 13

A. Mucous cells, Serous cells, Acinar cells (demilune of serous cells), intercalated duct, salivary duct (Secretory)
B. Acini
- basally located nuclei
- abundant RER
- apical secretory granules
Ducts
- intercalated ducts: drain acinar fluid
- striated ducts: modify the ion composition of saliva + change the osmolarity and tonicity of the fluid
- excretory duct: fluid flows to the mouth

Question 14

A-amylase

Answer 14

Breaks down carbs

Question 15

Lipase

Answer 15

Breaks down lipids

Question 16

Mucin glycoproteins

Answer 16

1. Lubrication
2. Antimicrobial
3. Protease protective