Salivary & Gastric Secretions Flashcards
What is the function of saliva?
initial digestion
dilution and buffering
lubrication with mucus
oral hygiene
evaporative cooling in doggies
Dogs on dry foot produce mostly ______ saliva
serous (watery)
What are the 3 major salivary glands?
parotid glands
submandibular glands
sublingual glands
zygomatic gland in dog and cat
Parotid glands are comprised of
serous cells
aqueous fluid (water, ions, enzymes)
Sublingual and submandibular are ______
mixed glands with serous
and mucus cells (mucin glycoproteins)
The salivary gland is described as a “bunch of grapes”. Each “grape” is a _______. Define it.
acinus
lined with acinar cells
produce initial saliva -composed of water, ions, enzymes, mucus
Initial saliva passes through a ________, then to ______
intercalated duct
then striated duct
Striated ducts are lined with
ductal cells that alter concentration of ions in saliva
What causes myoepithelial cells to contract and eject saliva?
neural stimulation
What has both PNS and SNS innervation in salivary glands? What dominates?
acinar
ductal cells
PSNS
Do salivary glands have high or low blood flow? It [increases/decreases] when saliva is ejected.
high
increases
What is saliva composed of?
water
electrolytes
amylase (some)
lingual lipase
kallikrein
mucus
What is kallikrein?
enzyme in glands, plasma, brain, tissues
- regulates local vasodilation associated with secretion
- part of saliva
Saliva is [hypertonic/hypotonic] compared to plasma.
hypotonic
What are the steps in saliva formation?
- formation of isotonic solution by ACINAR cells
- modification of solution by DUCTAL cells to become hypotonic
Fill in the blanks.
- NaCl (leaves)
- K+ and HCO3- (enters)
What are the luminal membrane transporters for saliva?
Na/H+ exchange
Cl-/HCO3- exchange
H+/K+ exchange
What are the basolateral membrane transporters for saliva?
Na+/K+ ATPase
Cl- channels
Fill in the blanks.
- NaCl
- K+, HCO3
- Na+/H+ exchange
- Cl-/HCO3- exchange
- H+/K+ exchange
- Na+/K+ ATPase
- Cl- channels
Absorption of _____ and _____ into blood means there is [high/low] concentrations in saliva.
Na+, K+
low
______ and ______ is secreted into saliva.
K+ and HCO3-
How is saliva hypotonic?
ductal cells are impermeable to water, so they don’t follow NaCl- from saliva to blood
- water stays in saliva
What organic components do acinar cells secrete?
alpha-amylase (human and pig)
lingual lipase
mucin glycoproteins
IgA
Kallikrein
At high flow rates (4 mL/min), final saliva _________.
resembles plasma (less time to modify saliva)
At low flow rates (<1 mL/min), final saliva ________.
is hypotonic
HCO3- concentration is [lowest/highest] at low flow rates and [lowest/highest] at high flow rates.
lowest, highest
Ruminants have [high/low] flow rates and thus dump a lot of ______.
high
HCO3-
T/F: Salivary secretion has both neural and hormonal control.
FALSE - ONLY NEURAL
Salivary secretion is stimulated by ______ stimulation.
parasympathetic AND sympathetic
PNS innervation of salivary secretion is carried on _____ nerves and its postganglionic neurons release _____
facial & glossopharyngeal nerves
acetylcholine (Ach)
SNS innervation of salivary secretion innervates _____ and synapse on ________ ganglion. Its postganglionic neurons release _____
T1-T3
superior cervical ganglion
norepinephrine (NE) — BETA ADRENERGIC
PNS postganglionic neurons release Ach which act on _______ receptors on _______ and _______ cells. It uses IP3 and Ca2+
muscarinic
acinar and ductal
SNS postganglionic neurons release NE which act on _______ receptors on _______ and _______ cells. It uses cAMP
beta-adrenergic
acinar and ductal cells
List the components of gastric juice.
HCl
Pepsinogen
Intrinsic factor
Mucus
What initiates PROTEIN digestion in the stomach?
HCl
pepsinogen
What do HCl and pepsinogen do?
initiates protein digestion
- part of gastric juice
Define intrinsic factor
essential for absorption of vitamin B12 in the ileum
- part of gastric juice
Define mucus
protects gastric mucosa from all the acid being produced
- part of gastric juice
The body of the stomach contains ______ glands
oxyntic glands
Pits, or openings, are lined with ______ at the body of the stomach.
epithelial cells
Mucous neck cells secrete ______
mucus
Parietal cells secrete ________
HCl
intrinsic factor
Chief cells secrete _________
pepsinogen
The antrum of the stomach has ______ glands.
pyloric
Pyloric glands have which types of cells?
G cells (gastrin)
mucous neck cells (mucus, HCO3, pepsinogen)
T/F: A low pH activates pepsinogen
TRUE
What is the first step in HCl secretion?
CO2 combines with H2O to form H2CO3 —> dissociates into H+ and HCO3-
In HCl secretion, H+ goes into [lumen/blood], and HCO3- goes into [lumen/blood]
HCl: lumen
HCO3-: blood
What is responsible for the “alkaline tide” in gastric venous blood after a meal?
absorbed HCO3-
HCO3- in the gastric vein is eventually secreted back into the GIT via ________
pancreatic secretions
In HCl secretion, Cl- follows H+ into [lumen/blood] by diffusing through Cl- channels
lumen
What 3 substances stimulate H+ secretion?
histamine (paracrine)
Ach (neurocrine)
gastrin (hormone)
Histamine is released from _____ cells in GASTRIC MUCOSA
ECL cells
In HCl secretion, histamine binds to _____ receptors on [parietal/chief] cells
H2
parietal
Ach is released from ______ innervating gastric mucosa
vagus nerve
In HCl secretion, Ach binds _______ receptors in [parietal/chief] cells
muscarinic
parietal
What is the second messenger for histamine?
cAMP
What is the second messenger for Ach in HCl secretion?
cAMP
Gastrin is secreted by ______ cells in stomach ANTRUM
G
Gastrin binds ________ on [parietal/chief] cells
CCKB (which binds gastrin and CCK)
parietal
What is/are the second messengers for gastrin in HCl secretion?
IP3/Ca2+
_______ and ______ stimulates ECL cells to release histamine
Ach
gastrin
What blocks H2 receptors and action of histidine?
cimetidine
What blocks Ach from binding to muscarinic receptors?
atropine
What gives the strongest response to stimulate H+?
potentiation
Define potentiation
sum of multiple stimuli cause greater response than sum of individual
- strong interaction of histamine with Ach OR gastrin
How does omeprazole inhibit H+ secretion?
irreversibly blocks acid secretion while bound NO MATTER THE STIMULUS
