PHYS: Salivary Secretion Flashcards
What is the word for a mixture of proteins, water and electrolytes that is secreted by various glands?
saliva
What gland secretes a serous secretion of water, ions, and enzymes?
parotid glands
Which glands secrete a mixed serous and mucous secretion?
Submandibular and Sublingual glands
What secretes mucus for lubrication?
lips and tongue glands
What are the 3 major roles of saliva?
Digestion
Lubrication
Protection
What are the two enzymes present in saliva?
Salivary amylase
Lingual lipase
What is the role of salivary amylase?
responsible for 50-70% of starch digestion (but if absent, not a problem for body)
How long will salivary amylase digest food?
until it reaches the stomach (pH optimum of 7, so inactivated by gastric acid)
What is the role of lingual lipase?
digests TGs and fat
How long will lingual lipase digest food?
into the stomach (not inactivated by acid in stomach, because pH optimum is 4)
Why is solubilization important?
allows you to taste food
Why is lubrication important?
speech and bolus movement
In what ways does saliva serve a protective role?
- Allows you to expel noxious material
- Thermally dilutes things (decrease temperature of hot foods)
- Alkaline to protect from damage and dental caries associated with vomit and acidic foods
What causes an increase in saliva in the mouth before vomiting?
vagal reflex
What saliva component chelates iron to decrease bacterial growth?
lactoferrin
What saliva component destroys bacteria?
lysozyme
binding protein for IgA also helps to kill bacteria
What cells make saliva?
acinar cells
What are acinar cells?
grape-like cells that elaborate proteins, water and electrolytes when they are squeezed
What “squeezes” acinar cells to cause secretion of saliva?
the myoepithelial cells that surround the acinar cells
From the acinar cells, where is saliva secreted?
into the intercalated duct→ salivary (striated) duct→ mouth
What disease is characterized by the destruction of salivary glands?
Sjogren’s syndrome
True or false: saliva is always isotonic.
FALSE: always hypotonic (though less so at high rates of secretion)
What are two other characteristics (other than hypotonicity) of saliva?
Alkaline
High K+
What ions are secreted into the acinus?
Na+
Cl-
HCO3-
Why is the saliva high in K+ and HCO3- and hypotonic?
as the saliva moves from the acinus to the duct opening, K+ and HCO3- are secreted into the lumen and Na+/Cl- are reabsorbed (while water is NOT)
What does the saliva resemble with high flow rates? Why?
final saliva closely resembles plasma and initial saliva produced by acinar cells (less time for the ductal cells to modify the saliva).
What is another feature of saliva during high flow rate?
HCO3- is high in this saliva because its secretion is selectively stimulated when saliva production is stimulated.
What would you give a patient who has high flow rates of saliva?
give back bicarbonate and K+ (no matter what, K+ is always secreted at a 4-5X higher level than plasma
What are characteristics of saliva at low flow rates?
saliva is most dissimilar to plasma (lower NaCl and higher K+)
True or false: regulation of salivary secretion is totally under nervous control.
TRUE
True or false: no hormones are involved in the regulation of salivary secretion.
TRUE
True or false: hormones cannot modify salivary secretions.
FALSE- though hormones do NOT regulate salivary secretion, they can modify the secretions
What is the major nervous effector of salivary secretion?
parasympathetic innervation
What is the name of the parasympathetic response that increases salivation?
Cephalic response
What are stimuli that initiate the cephalic response?
smell
taste
pressure
nausea
What do the stimuli of the cephalic response do?
stimulate salivary nucleus of the medulla and activate CN IX and X
What do CN IX (glossopharyngeal) and X (vagus) do in the cephalic response in response to stimulation?
release Ach molecules that act through M receptors to increase IP3 and Ca2+ in the salivary gland
What does increasing levels of Ca2+ do in salivary glands?
increase saliva secretion
Increase blood flow
How does increased Ca2+ increase blood flow?
Increases cellular metabolism→ increased kallikrein→ increased bradykinin from plasma proteins→ HUGE blood flow increases
What inhibits the salivary nucleus of the medulla?
fatigue
sleep
fear
dehydraiton
What are the sympathetic effectors (minor) involved in the regulation of salivary secretion?
T1-T3
How do T1-T3 lead to increased salivary secretion?
T1-T3 act on superior cervical ganglion→ release of NE→ beta-adrenergic receptors to increase cAMP and cause saliva secretion
