Lecture 6 - Salivary Glands Flashcards
major salivary glands and ducts
are the parotid and sublingual glands
what comprises the secretory apparatus?
multiple salivons each composed of an acinus lined by a secretory cells and connected to a duct lined by cells that can modify the electrolyte content of the primary acinar secretion as it passes thru the mouth
what are electrolytes in saliva derived from?
serum
what are the two major types of salivary secretion?
- serous secretion containing electrolytes, lipase (fat digestion), and ptyalin (an alpha-amylase - an enzyme for digesting starches)
- mucous secretion for lubrication.
partoid gland secrete what type of saliva?
serous
submandibular and sublingual gland secrete what type of saliva?
serous and mucous
buccal gland secretes what type of saliva?
mucous
what is the pH of saliva? what type of digestion does htis favor?
6.0 - 7.4 which favors the digestive action of ptyalin
in what species is salivary amylase present?
pig, absent in horse, sheep, goat, cow, dog and cat
what compounds are dominant in ruminant saliva?
Na and HCO3
what compounds are dominant in equine saliva?
Cl and Ca
what compound is present in ruminant saliva and used by rumen microbes to synthesize protein?
urea! a portion of this protein can be digested in the small intestine to be used as an amino acid source and an effective means of removing and recycling ammonia
what are the volumes of saliva like in herbivores?
high - approx 200 liters/day in ruminants
functions of salivary glands
- mastication and deglutition
- evaporative cooling in dog and cat
- provision of fluid and buffer in ruminants for forestomach digestion
what are the major buffers in saliva?
bicarb and phosphate (mostly from parotid)
do salivary glands play a critical role in digestion?
no - you can remove one without a problem
what does primary secretion from the acinus consist of?
Na, Cl, and HCO3 which are actively transported from the blood
what happens as saliva passes down the collecting ducts?
its modified by exchange of Na, H and K ions and active resabsorption of NaCl.
does water osmotoically equilibriate in saliva?
no - the duct epithelium is tight so the water does not osmotically equilibriate with ions as they are absorbed so that the osmolality is hypotonic at low rates of flow in nonruminants.
what is the osmalality of ruminant saliva at all rates of flow?
isotonic
what does cholinergic stimulation cause?
an increase in flow rate
where does acetylcholine act?
at muscarinic junctions which is the site of parasympathetic postganglionic action
what does atropine block?
it selectively interferes with Ach action at muscarinic junctions to effectively block parasympathetic effects
this is used to suppress salivary secretions and ronchial secretions before surgery
what is the effect of adrenergic stimulation?
produces a more viscous fluid, high in protein