Secretions from Salivary Glands & Stomach Flashcards

1
Q

what’s triggered by anticipation of food?

A

autonomic and endocrine reflexes
acts to prepare GI tract

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2
Q

what are the three phases of salivary gland secretion?

A

cephalic
gastric
intestinal

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3
Q

what’s the cephalic phase of saliva secretion?

A

food anticipation

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4
Q

what’s the gastric phase of salivary secretion?

A

mechanical stim of oral cavity and stomach

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5
Q

what’s the intestinal phase of saliva secretion?

A

regulation of stomach emptying and digestion/absorption in SI

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6
Q

what glands produce saliva?

A

parotid, mandibular, lingual, buccal

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7
Q

what is the major source of water and bicarb to a cattle rumen?

A

SALIVA

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8
Q

what’s saliva made of?

A

mostly water
som electrolytes
salivary protein
urea (ruminants)

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9
Q

saliva functions

A

solvent for molecules to stimulate taste buds, food lube, keeps mouth clean, has buffer/lysozymes/antitoxic

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10
Q

salivary glands are ___ glands

A

acinar

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11
Q

what are acini?

A

secretory units

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12
Q

fluid is secreted into the lumen of acini and is ___ on the way through intercalated and striated ducts

A

modified

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13
Q

what is a salivary mucocele?

A

painless swelling of neck or in oral cavity
caused by saliva collection from a damaged salivary gland/duct

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14
Q

what creates hypotonic saliva?

A

iso-osmotic secretion by acini cells and selected reabsorption by duct cells

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15
Q

how do acini cells release proteins and mucus?

A

exocytosis

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16
Q

what do acini cells secrete?

A

Cl-, bicarb, K+, Na+, water

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17
Q

duct cells ___ Na+ and Cl- in exchange for H+ and bicarb

A

reabsorb

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18
Q

__ is recycled for K+

A

H+

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19
Q

saliva osmolarity is determined by ___

A

flow rate

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20
Q

saliva is ___ at low flow rates

A

hypotonic

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21
Q

at high flow rates, ___ concentration increases in saliva.

A

electrolyte

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22
Q

what happens to saliva in relation to plasma during high flow rates?

A

saliva becomes isotonic in relation to plasma

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23
Q

protein concentration ___ affected by saliva flow rate

A

IS NOT

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24
Q

saliva from different glands varies in ___ concentration

A

protein

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25
serous means more ___
protein
26
mucous means ___
more glycoproteins aka proteins with oligosaccharide chains
27
parotid gland consists of...
serous cells providing protein to saliva
28
sublingual, submandibular glands contain...
mix of mucus and serous cells
29
what is ptyaline (alpha amylase)?
initiates starch digestion in pigs and humans NOT carnivore/horse
30
where is lingual lipase most frequently present?
young animals on milk diet
31
what does lingual lipase do?
initiates hydrolysis of triglycerides into diacylglyceride and free FA
32
in ruminants and herbivores, saliva consists of ___ and ___ proteins
lysozymes antitoxic protein
33
what are the antibacterial effects of lysozymes?
hydrolytic enzymes *loss of peptidoglycan integrity results in rapid cell lysis in hypo-osmotic environment
34
what are tannins?
phenolic compounds made by plants as defense mechanism against herbivores creates bitter taste to reduce tasteness has NEGATIVE GI tract effect
35
tannins cause a ___ of food intake, ___ in ruminal protein degradation, and ___ digestive enzymes by binding and forming insoluble complexes
REDUCTION/INHIBIT
36
which species likely has a bigger parotid gland?
browser >> grazer
37
how is tannin neutralized?
parotid glands producing proline rich proteins
38
browsers eat plant material with ___ tannin concentrations. they have ___ parotid glands than grazers
higher, larger
39
explain the buffer function of saliva in ruminants
buffers rumen fluid microbial activity constantly produces VFA, which is buffered by bicarb from saliva. ruminant saliva pH 8, has NO enzymes
40
what are the four components of gastric juice?
HCl pepsinogen mucus intrinsic factor
41
what does the HCl do in gastric juice?
reduces pH of stomach, activates pepsinogen, aids in protein digestion, kills bacteria
42
what does pepsinogen do i gastric juice?
inactive/active digests protein
43
what does mucus do in gastric juice?
protects gastric mucosa from corrosive actions of HCl
44
what does the intrinsic factor do in gastric juice?
necessary for absorption of vitamin B12 in ileum
45
which species have glandular mucosa in stomach?
dog, cat
46
which species have non-glandular mucosa in stomach?
horse, rats
47
the epithelium in the glandular region contains what type of cells?
parietal chief enteroendocrine
48
what do chief cells do?
pepsinogen -> pepsin
49
what do surface mucus cells do?
produce thick, tenacious mucus, protective function against acid and mechanical damage
50
what do mucus neck cells do?
thin mucus progenitor cells can do mitosis
51
what doe D cells, G cells, ECL cells do?
produce hormones that regulate gastric secretion and motility
52
what do parietal cells secrete? what pumps are used?
H+ and Cl- H+ via...ATP pumps, exchange H+ against K+ Cl- via...passive movement down electrogenic gradient
53
where is HCl formed in stomach?
gastric lumen
54
what is Cl- exchanged for on basolateral membrane?
bicarb
55
what is the "alkaline tide"?
Cl- exchanged for bicarb HCO3-/Cl- exchange on basolateral side to bring in Cl- and cause alkaline tide (temporary pH increase in blood)
56
explain neural control of HCl secretion
PNS and ENS activate parietal cells via M3 receptors
57
explain endocrine control of HCl secretion
secretion of GASTRIN from G cells binds to CCK-B receptors secretion of HISTAMINE from ECL binds to H2 receptors
58
what is histamine released in response to?
gastrin
59
what is gastrin released in response to?
small peptides and AA in stomach distension of stomach vagal stimulation
60
what are the two mechanisms that mediate activation of H-K ATPase and therefore HCl stimulation?
1. by the PNS (ACh) and by gastrin through G protein coupled receptors, which stimulates IP3/DAG which increases Ca2+ concentration 2. by histamine receptors that mediate elevation of cAMP concentration
61
Ca2+ and cAMP ___ the proton pump
stimulate
62
what is the main control of reducing parietal cell activation?
pH measured by G cells pH < 2 triggers negative feedback
63
the absence of food causes ____ of HCl production
downregulation
64
what two hormones cause the downregulation of HCl production?
somatostatin and prostaglandin
65
what is the gastric mucosal barrier?
protects stomach epithelial lining against acidic environment
66
what happens if the gastric mucosal barrier is broken?
acid could then diffuse across mucosa and damage the stomach wall
67
what are the three components of the gastric mucosal barrier?
compact epithelial lining gastric mucus covering bicarb secreted by surface epithelial cells which creates neutral micro-environment
68
what is a gastric ulcer?
localized area of erosion due to improper mucus layer causes = defect in mucosal barrier, HCl hypersecretion, heliobacter pylori
69
what are the therapeutic approaches for gastric ulcers?
reduce acid production (via vagotomy, drugs) stimulate re-epithelization antibiotics for helicobacter
70
what is pepsinogen produced/secreted by?
chief cells
71
how is pepsinogen stored in chief cells?
stored in zymogen granules, released by exocytosis
72
why is pepsin released as a proenzyme?
prevent AUTODIGESTION proenzyme is converted to active pepsin by HCl in stomach lumen
73
what is the function of pepsin?
cleaves proteins to peptides at aromatic links digests 10-20% of proteins in a meal
74
explain the stimulation of pepsinogen