OCB02-2020 Physiology of salivary glands

Question 1

Are salivary glands exocrine or endocrine glands?

Answer 1

Exocrine

Question 2

Where do parotid glands secrete saliva?

Answer 2

at the level of the upper second molar on the buccal surface

Question 3

Where do submandibular and sublingual glands release saliva?

Answer 3

Under the surface of the tongue on either side of the frenulum

Question 4

What is the major duct of the parotid gland called?

Answer 4

Stenson duct

Question 5

What is the major duct for the submandibular gland called?

Answer 5

Wharton duct

Question 6

What stimuli cause saliva production?

Answer 6

Nociception
Thermoreceptive
Olfactory
Masticatory
Gustatory

Question 7

Where do the afferent and efferent nerves travel?

Answer 7

Via the afferent pathway to the Solitary nucleus in the medulla oblongata
Efferent nerves then travel from the ANS and thoracic spine to their effector organs

Question 8

Where does the parasympathetic nerves arise?

Answer 8

Salivatory nuclei in the brain (ANS)

Question 9

Where do the sympathetic nerves arise?

Answer 9

From the thoracic spine

Question 10

How do the parasympathetic and sympathetic NS affect saliva?

Answer 10

Increase saliva production

Question 11

How can salivary production be decreased?

Answer 11

Come from the salivary nuclei in the higher centres of the brain

Question 12

Do parotid glands receive parasympathetic or sympathetic innervation?

Answer 12

both

Question 13

Do submandibular glands receive parasympathetic or sympathetic innervation?

Answer 13

both

Question 14

Do sublingual glands receive parasympathetic or sympathetic innervation?

Answer 14

only parasympathetic

Question 15

Do minor salivary glands receive parasympathetic or sympathetic innervation?

Answer 15

only sympathetic

Question 16

What cells does the autonomic nerves supply?

Answer 16

Acini cells
Myoepithelial cells that surround acini
Ductal cells
Control blood vessel

Question 17

What are the parasympathetic effects of reflex stimuli from autonomic nerves?

Answer 17

Can act in isolation
Stimulates most fluid secretion 
Evoke some protein secretion 
Contract my-epithelial cells 
Cause vasodilation as part of the secretory process
Denervation causes gland atrophy

Question 18

What are the sympathetic effects of reflex stimuli from autonomic nerves?

Answer 18

Acts synergistically with parasympathetic nerves
Causes less fluid secretion, but most protein secretion
Contracts my-epithelial cells
Denervation causes gland atrophy

Question 19

How does the sympathetic NS act and on what receptors?

Answer 19

Via noradrenaline on B adrenergic receptors

Question 20

How does the parasympathetic NS act and on what receptors?

Answer 20

Ach on M3 muscarinic receptors

Question 21

How is saliva formed via the PaNS in stage 1?

Answer 21

When acetylcholine is secreted from the PaNS, it stimulates NaCl secretion which created an osmotic gradient allowing water to also enter the duct

Question 22

How is saliva formed via the sympathetic NS in stage 1?

Answer 22

Sympathetic secretion via noradrenaline increases protein secretion into the duct therefore at this stage, the secretion is isotonic

Question 23

How is saliva modified in stage 2?

Answer 23

As saliva moves down the duct, NaCl is removed by ductal cells, creating a hypotonic solution of saliva .
The ductal epithelium is impermeable to water, so water is retained and salt reduced

Question 24

What neurotransmitters do minor glands rely on?

Answer 24

VIP (protein secretion)
Substance P (fluid secretion)

Question 25

What is the coupling of autonomic sympathetic stimulation to saliva secretion in acinar cell?

Answer 25

With sympathetic stimulation, noradrenaline leads to an increase in cAMP, which leads to protein secretion

Question 26

What is the coupling of autonomic parasympathetic stimulation to saliva secretion in acinar cell?

Answer 26

Acetylcholine activates the IP3 pathway, which causes a rise in intracellular calcium which leads to electrolyte and water secretion

Question 27

What is fluid and electrolyte secretion mediated by?

Answer 27

Calcium signalling pathway

Question 28

What is protein secretion mediated by?

Answer 28

cAMP pathway

Question 29

What drug reduces protein secretion?

Answer 29

Propranolol

Question 30

What drug reduce fluid secretion?

Answer 30

Atropine

Question 31

What is salivary secretion dependant on?

Answer 31

Sodium concentration gradient | The opening of apical chloride channels upon stimulation of acinar cells

Question 32

How is saliva secreted?

Answer 32

There are low intracellular concentrations of sodium and high extracellular due to the Na-K pump When acetylcholine binds to M3 receptors, it causes increase in intracellular calcium ion concentrations allowing the opening of chloride ion channels This allows chloride to move from the intracellular space to the extracellular ductal environment This creates an electrochemical gradient allowing sodium ions to move to the apical sides The Na-K pump regulates intracellular ion concentration, maintaining high intracellular conc of chloride for saliva flow

Question 33

When does saliva secretion stop?

Answer 33

Stops when acetylcholine stops occupying the muscarinic receptor, the intracellular calcium is reduced and taken back to RER

Question 34

What is the most abundant Ig in saliva?

Answer 34

sIgA

Question 35

What protein does the the parotid gland contain a lot of?

Answer 35

Amylase

Question 36

What protein does the the sublingual gland contain a lot of?

Answer 36

Mucins

Question 37

What are the types of secretion of all glands?

Answer 37

Parotid: serous Submandibular: Serous and mucous Sublingual: mucous

Question 38

How do ductal cells modify saliva when resting?

Answer 38

Striated ducts remove Na+ and Cl- K+ is secreted into the lumen Straited ducts are impermeable to water So saliva is hypotonic in the mouth

Question 39

When are the salivary glands resting?

Answer 39

When it is not responding to the intake of food

Question 40

How is saliva modified when salivary glands are stimulated?

Answer 40

There is a larger volume of saliva produced and higher rate of flow of isotonic saliva

Question 41

How does the composition of saliva change when it is stimulated?

Answer 41

More Na+ and Cl- is present but less K+ HCO3- is also present It is less hypotonic as less ions are removed by ductal cells, as greater volumes are secreted so less time for fluid to come into contact with ductal epithelium and be modified