Physiology of the Mouth, Pharynx and Oesophagus

Question 1

Name 8 functions of saliva.

Answer 1

1. Lubricates and wets food for swallowing.
2. Helps with taste.
3. Begins digestion of starch (via a-amylase) and lipids (via lingual lipase).
4. Keeps mucosa moist.
5. Cools hot food.
6. Contents destroys bacteria.
7. Washes away bacteria and food particles.
8. Maintains an alkaline environment.

Question 2

Approximately how much saliva do we produce each day?

Answer 2

800-1500ml.

Question 3

What is the pH range of saliva?

Answer 3

6.2-8

Question 4

What is osmosis?

Answer 4

The movement of water across a semi-permeable membrane from an area of low-solute concentration to high-solute concentration.

Question 5

What is osmolarity?

Answer 5

The concentration of osmotically active particles per litre of solution (mOsm/L).

Question 6

What is osmolality?

Answer 6

The concentration of osmotically active particles per kg of water (mOsm/kg).

Question 7

What is tonicity? How is it determined?

Answer 7

Tonicity is a measure of the osmotic pressure gradient between two solutions separated by a semi-permeable membrane. It’s determined by the relative osmolarities of the two solutions.

Question 8

Name 6 components of saliva.

Answer 8

1. Water
2. High K+, HCO3-, and Ca2+ (relative to plasma)
3. Low Na+ and Cl- (relative to plasma)
4. Mucous
5. Digestive enzymes - salivary a-amylase, lingual lipase
6. Antibacterial agents - thiocynate ions, antibodies

Question 9

Why does saliva contain a high amount of HCO3-?

Answer 9

To maintain an alkaline environment.

Question 10

Why does saliva contain a high amount of Ca2+?

Answer 10

To prevent calcium from moving out of the teeth down a concentration gradient.

Question 11

How many main pairs of salivary glands are there? What are they?

Answer 11

1. Parotid
2. Sublingual
3. Submandibular

Question 12

What type of saliva is secreted by the Parotid salivary glands?

Answer 12

Serous saliva - watery and rich in enzymes.

Question 13

What type of saliva is secreted by the Sublingual salivary glands?

Answer 13

Mucus saliva.

Question 14

What type of saliva is secreted by the Submandibular salivary glands?

Answer 14

Mixed serous and mucus.

Question 15

What are the minor salivary glands located on the inner sides of the cheeks?

Answer 15

Buccal glands.

Question 16

What is the name of the minor salivary glands located towards the back of the tongue? What do they secrete?

Answer 16

Von Ebner’s glands of the tongue, which secrete digestive enzymes such as amylase and lipase.

Question 17

What are the 3 main types of cells in salivary glands?

Answer 17

1. Acinar cells
2. Ductal cells
3. Myoepithelial cells

Question 18

What is the role of the acinar cells of the salivary glands?

Answer 18

The initial secretion of saliva.

Question 19

What is the role of the ductal cells of the salivary glands?

Answer 19

To modify the saliva/ its ionic content.

Question 20

What is the role of the myoepithelial cells of the salivary glands?

Answer 20

To contract to eject saliva into the oral cavity.

Question 21

When saliva is being modified by the ductal cells which is greater, the absorption of Na+ and Cl- or the secretion of K+ and HCO3-? How does this affect the tonicity of the saliva?

Answer 21

The absorption of Na+ and Cl- is greater, therefore there is a net absorption of solute. Water would ordinarily follow, but because the ductal cells are relatively impermeable to water, water becomes trapped in the ducts, resulting in a hypotonic solution.

Question 22

What is the degree of modification of saliva dependent on?

Answer 22

Flow rate.

Question 23

What is the name for saliva that has a low degree of modification and is therefore similar to the initial saliva produced by the acinar cella?

Answer 23

Stimulated saliva.

Question 24

Which is the only substance in saliva that increases with increasing flow rate?

Answer 24

Bicarbonate (HCO3-).

Question 25

Which is more hypotonic, resting or stimulated saliva?

Answer 25

Resting.

Question 26

Which is more alkaline, resting or stimulated saliva?

Answer 26

Stimulated (Bicarbonate increases with flow rate).

Question 27

What is xerostomia?

Answer 27

A condition in which the salivary glands in your mouth don't make enough saliva to keep your mouth wet.

Question 28

What are some symptoms of xerostomia?

Answer 28

``` Dry mouth/ tongue/ lips. Halitosis Problems swallowing and speaking Altered taste Periodontal disease Oral infections, e.g. candidiasis Burning sensation in mouth ```

Question 29

What is the medical term for taste?

Answer 29

Gustation

Question 30

What are the 5 taste classifications?

Answer 30

1. Sweet 2. Sour 3. Bitter 4. Salty 5. Umami

Question 31

What kind of receptors are taste receptor cells?

Answer 31

Chemoreceptors

Question 32

What 3 cells comprise a taste bud?

Answer 32

1. Taste receptor cells 2. Supporting cells 3. Basal cells

Question 33

Is the lower oesophageal sphincter an anatomical or physiological sphincter?

Answer 33

Physiological

Question 34

What are the 3 phases of swallowing. Are they voluntary or involuntary?

Answer 34

1. Oral phase - voluntary 2. Pharyngeal phase - involuntary 3. Oesophageal phase - involuntary

Question 35

What happens during the oral phase of swallowing?

Answer 35

1. The tongue moves the bolus backwards to oropharynx. 2. Sensory receptors in the palette and pharynx send signals via cranial nerves to the swallowing centre located in the medulla in the brainstem, this initiates the swallowing reflex.

Question 36

What happens during the pharyngeal phase of swallowing?

Answer 36

1. The soft palate elevates which blocks off the nasopharynx. 2. The glottis closes. 3. The larynx elevates. 4. The epiglottis tilts and covers the opening of the larynx.

Question 37

What happens during the oesophageal phase of swallowing?

Answer 37

1. The upper oesophageal sphincter closes. 2. Larynx falls, glottis opens, respiration commences. 3. Primary peristaltic wave. 4. Lower oesophageal sphincter relaxes.

Question 38

Name some causes of dysphagia.

Answer 38

``` Xerostomia Cleft lip/palette Tonsilitis Oesophageal carcinoma Achalasia Dementia Parkinson's ```

Question 39

What is Achalasia?

Answer 39

A primary oesophageal motility disorder characterised by the absence of oesophageal peristalsis and impaired LES relaxation in response to swallowing.

Question 40

What is a pharyngeal pouch? What is this disorder also known as?

Answer 40

A pharyngeal pouch is a small bulge or pocket, like a hernia, that occurs in the pharynx. Also called Zenker's diverticulum.