salivary gland physiology

Question 1

how does saliva protect?

Answer 1

• pH control (buffer by HCO3)
• maintenance of mineralized surfaces (saliva is supersaturated with CaPO4–favors remin)
• lubrication and hydration–viscous solution coats and sticks to surfaces
• formation of enamel pellicle: layer of salivary proteins deposited on tooth surface–diffusion barrier, attachment of bacteria

Question 2

how does saliva control oral microflora?

Answer 2

• direct killing: inhibition of bacterial, fungal growth, and possible antiviral activity
• agglutination and clearance by swallowing
• modulation of binding: favors attachment of benign species–have advantage over non-binding pathogens

Question 3

taste and digestion of saliva

Answer 3

• implicated in taste perception
• hydrolysis of strach initiated
• protection against dietary components

Question 4

blood clotting with saliva

Answer 4

reduced bleeding time in oral cavity, saliva accelerates clotting

Question 5

protective components of saliva

Answer 5

• hypotonic mix of inorganic ions
• main buffering agent is bicarbonate
• supersaturated in calcium phosphate
• complex mix of over 50 proteins

Question 6

mucins

Answer 6

large, hydrophilic, hydrated molecules

-provide viscosity, pellicle component, binding site for bacteria, facilitate clearance by agglutination

Question 7

lactoferrin

Answer 7

binds iron

inhibits bacterial growth

Question 8

lysozyme

Answer 8

antimicrobial

acts on cell wall

Question 9

histatins

Answer 9

small histidine-rich peptides, powerful antifungals

Question 10

lactoperoxidase

Answer 10

forms hypothiocyanite ion, highly toxic to bacteria

Question 11

amylase

Answer 11

hydrolyzes starch

helps clear carbohydrate from teeth, may be antimicrobial

Question 12

secretory IgAs

Answer 12

may bind bacteria and facilitate clearance

Question 13

statherin

Answer 13

small tyrosine-rich peptide

inhibits spontaneous CaPO4 precipitation from saliva, could facilitate remin of small lesions in teeth

Question 14

proline-rich proteins**

Answer 14

most abundant salivary protein (up to 70%)
bind dietary tannins
major pellicle components
control calculus

Question 15

salivay glands are controlled mainly by—

Answer 15

parasympathetic signals

originate in superior and inferior salivatory nuclei in brain stem

Question 16

many taste stimuli increase secretion —- fold basal rates

Answer 16

8-20

Question 17

salivary glands secretion moderately increased by ____

Answer 17

sympathetic nervous signals

originate in superior cervical ganglia and travel alongside blood vessels to glands

Question 18

gland secretion involves two integrated processes:

Answer 18

1. production of a fluid
2. secretion of proteins (mainly by exocytosis)
   - different stimuli can elicit different mix of two systems

Question 19

parasympathetic stimulation leads to production of saliva at a high flow rate but with a _______ organic content

Answer 19

lower

Question 20

sympathetic stimulation leads to a relatively smaller increase of flow rate but more ____

Answer 20

viscous

Question 21

how do neurotransmitters start salivary secretion?

Answer 21

bind to specific receptors on basolateral surface of acinar cells
trigger production of specific intracellular messages
-messages trigger production of fluid/ion secretion and exocytosis of proteins

Question 22

sympathetic NT and receptor

Answer 22

norepinephrine (adrenergic)
alpha adrenergic (alpha 1 is main) and beta adrenergic (beta 1 is main)

Question 23

parasympathetic NT and receptor

Answer 23

acetylcholine–cholinergic

muscarinic

Question 24

majority of protein synthesized and secreted by —

Answer 24

acinar cells

Question 25

acini secrete approx isotonic mix of -----, ducts reabsorb -----, release -----

Answer 25

inorganic ions ducts reabsorb Na+, Cl- release K+ result is hypotonic solution

Question 26

unstimulated saliva flow rate for submandibular and sublingual

Answer 26

~63% | 0.04-0.40

Question 27

minor gland secretion makes up for what percent of secretion?

Answer 27

10%

Question 28

highly differentiated and polarized cells committed to production of proteins for exocrine secretion

Answer 28

acinar cells - -extensive RER - -large number of storage granules

Question 29

protein synthesis in salivary glands

Answer 29

1. stimulus dependent exocytosis of storage granules 2. basal level exocytosis of storage granules 3. immature granules provide 15% unstimulated secretion 4 & 5. low level constitutve epithelial pathways

Question 30

two stage process of salivary fluid formation

Answer 30

1. initially formed as nearly isotonic plasma-like secretion in acinar lumen 2. modified in ducts by removal of Na+, Cl-, and addition of K+, HCO3- with no further secretion or absorption of water to produce hypotonic solution

Question 31

steps for production of saliva

Answer 31

1. stimulation from PNS 2. acetylcholine muscarinic receptor 3. M3 for stimulation of saliva (odd # stimulation) 4. activate secondary messenger--diglyceride lipase 5. want initial Ca release--bind channels--> open voltage gated channels--> influx of Cl-

Question 32

adrenergic receptors

Answer 32

autonomic and bind to adrenaline and noradrenaline sympathetic nervous system adrenaline and noradrenaline alpha and beta receptors

Question 33

cholinergic receptors

Answer 33

autonomic receptors that bind to acetylcholine parasympathetic nervous system acetylcholine nicotinic and muscarinic receptors

Question 34

first stage for fluid secretion

Answer 34

cl- dependent | HCO3 dependent

Question 35

four membrane transport systems of fluid secretion

Answer 35

1. loop diuretic (furosemide, bumetanide)--sensitive Na/K/Cl ion cotransporter in acinar basolateral membrane 2. basolateral Ca activated K channel (allows K OUT) 3. basolateral Na/K ATPase (pumps Na out) 4. apical Ca activated Cl- channel

Question 36

in resting state, K and Cl---

Answer 36

concentrated in acinar cell above electrochemical equilibrium - -K by Na/K ATPase - -Cl by Na/K/Cl transporter

Question 37

when stimulated by alpha adrenergic or cholinergic what happens

Answer 37

- intracellular Ca increases - opens basolateral K channel; apical Cl- channel - K+ exits cell basolaterally - Cl- exits cell into lumen - net neg charge in lumen - Na+ follows Cl- by leaking from interstitium - creates NaCl osmotic gradient - causes transepithelial movement of water into lumen

Question 38

cl-dependent secretion model

Answer 38

entry of Cl across basolateral membrane mediated by Na/K/Cl2 cotransporter and paired Na/H and Cl-/HCO3 exchangers. -Cl exit across apical mem via Cl- channel