The Mouth

Question 0

How does saliva protect the oral environment?

Answer 0

Keeps mucosa moist
Washes teeth
Maintains alkaline environment to neutralise acid produced by bacteria
High calcium concentration to prevent teeth from dissolving

Question 1

Functions of saliva

Answer 1

Lubricates and wets food to help form a bolus
Begins digestion of carbohydrates with amylase
Prevents degradation of teeth with high calcium and being slightly alkaline

Question 2

What are the names of the three paired salivary glands?

Answer 2

Parotid
Submaxillary
Sublingual

Question 3

Type of secretion from the parotid gland? What proportion of total saliva?

Answer 3

Watery secretion rich in enzymes, little mucus

25%

Question 4

Type of secretion of submaxillary gland? What proportion of total saliva?

Answer 4

Serous and mucous

70%

Question 5

Type of secretion from sublingual? Proportion?

Answer 5

Viscous with no enzymes - lots of mucus

5% of total saliva

Question 6

Structure of salivary glands?

Answer 6

Blind-ended tubes lined with acinar cells
Connected to a system of ducts lined with duct cells
Lead to a single outlet

Question 7

Is saliva hyper or hypotonic?

Answer 7

Hypotonic

Question 8

How is saliva produced?

Answer 8

Isotonic fluid (primary secretion) secreted by acinar cells which contains enzymes
Duct cells remove Na and Cl, add HCO3-
Duct cells are impermeable to water so it cannot follow resulting gradient

Question 9

Under what conditions is saliva more hypotonic and why?

Answer 9

In low flow rates, most Na is removed because it is in contact with the duct cells for a longer time
Aldosterone also increases ductal recovery of Na

Question 10

When does saliva become more alkaline? Why?

Answer 10

At high flow rates

Duct cells are stimulated to release more HCO3- so it becomes more alkaline

Question 11

What controls saliva secretion?

Answer 11

Sympathetic - superior cervical ganglion

Parasympathetic - glossopharyngeal nerve and octic ganglion

Question 12

How does the parasympathetic nervous system control saliva secretion?

Answer 12

From the otic ganglion.
Ach is released which acts in acinar cells
Stimulated to produce primary secretion
Duct cells stimulated ago add extra HCO3-

Question 13

What drug can block the muscarinic receptors in the salivary glands?

Answer 13

Atropine

Question 14

How does the sympathetic nervous system control saliva secretion?

Answer 14

Reduces blood flow to salivary glands, limiting salivary flow.
(Produces typical ‘dry mouth’ anxiety)

Question 15

Where is autonomic outflow coordinated in regard to affecting saliva?

Answer 15

Centres in the medulla

Question 16

What is saliva produced in response to?

Answer 16

Smell and taste of food

Conditioned reflexes

Question 17

How much saliva is produced each day?

Answer 17

1.5L

Question 18

Condition where there is no saliva production?

Answer 18

Zerostomia

Question 19

What happens if there is reduced saliva production?

Answer 19

Difficult to eat food, needs to be moist or had with a drink

Teeth and mucosa degrade within weeks

Question 20

What does saliva contain?

Answer 20

Na, Cl (lower concs than plasma)
Ca, K, I (higher concs than plasma)
HCO3, bacteriostats, mucus, enzymes

Question 21

Main enzyme in saliva?

Answer 21

Amylase

Question 22

Spinal levels of oesophagus?

Answer 22

From C6-T11

Question 23

Three phases of swallowing?

Answer 23

Voluntary phase
Pharyngeal phase
Oesophageal phase

Question 24

What happens in the voluntary phase of swallowing?

Answer 24

Mastication produces a bolus which is moved to the pharynx

Question 25

What do swallowing centres in the brain stem cause in the pharyngeal phase of swallowing?

Answer 25

Closure of the glottis
Inhibition of respiration
Raises larynx
Opens upper oesophageal sphincter

Question 26

What happens in the oesophageal phase of the swallowing?

Answer 26

Parasympathetic stimulation causes a rapid peristaltic wave, coordinated by extrinsic nerves
Food gets to stomach in 9 seconds
Lower oesophageal sphincter opens

Question 27

Which nerve innervates the muscles of mastication?

Answer 27

Trigeminal nerve

Question 28

Composition of resting saliva?

Answer 28

Low volume
Hypotonic
Neutral/slightly acidic
Few enzymes

Question 29

Composition of stimulated saliva?

Answer 29

High volume
Less hypotonic
More alkaline
Lots of enzymes