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PSIO EXAM 3 > Gastrointestinal Physiology intro through Cephalic phase > Flashcards

Gastrointestinal Physiology intro through Cephalic phase Flashcards

1
Q

what are paracrines

A

ex histamine and somatostatin

act like hormones but only travel short distances

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2
Q

how do paracrines act in GI regulation

A

endocrine cells of the GI tract release paracrines that use diffusion to travel into the target cells

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3
Q

in basic terms how does the sympathetic nervous system control the GI tract, what neurotransmitter does it release

A

An increase in sympathetic activity slows GI processes through decreasing motility and secretions, and increasing the constriction of sphincters
the sympathetic nervous system releases the neurotransmitter norepinephrine

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4
Q

in basic terms how does the parasympathetic nervous system control the GI tract, what neurotransmitters does it release

A

An increase in parasympathetic activity promotes GI processes (digestion and absorption) through increases in motility and secretions, decreasing the constriction of sphincters, and increases in the release of gastrin acid secretion
the sympathetic nervous system releases the neurotransmitters acetylcholine, vasoactive intestinal polypeptide, and gastrin- releasing peptide

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5
Q

how does acetylcholine act on the GI tract

A

it is released by the parasympathetic nervous system and causes increases in motility and secretions

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6
Q

how does Vasoactive intestinal polypeptide act on the GI tract

A

it is released by the parasympathetic nervous system and causes decreases constriction of sphincters, enables movement

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7
Q

how does gastrin releasing peptide act on the GI tract

A

it is released by the parasympathetic nervous system and causes an increase in the gastrin acid secretion

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8
Q

What is the source hormone secretin, what stimulus causes it to be released?

A

S cells in lining duodenum

acid entering the duodenum

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9
Q

how does secretin act on stomach motility and secretions?

A

Secretin inhibits stomach motility and secretions

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10
Q

how does secretin act on the pancreas?

A

stimulates HCO3- secretion

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11
Q

What is the source hormone CCK, what stimulus causes it to be released?

A

I cells in the lining of the duodenum

fat and amino acids entering duodenum

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12
Q

how does CCK act on stomach motility and secretions?

A

CCK inhibits emptying

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13
Q

how does CCK act on the pancreas?

A

CCK stimulates the pancreas

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14
Q

how does CCK act on the gall bladder?

A

release of CCK contracts the gallbladder and replaces the sphincter of Oddi

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15
Q

What is the source hormone gastin, what stimulus causes it to be released?

A

G feels of the stomach

stomach distention

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16
Q

how does Gastrin act on stomach motility and secretions?

A

gastrin stimulates stomach motility and secretions

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17
Q

how much of the cardiac output does the GI system receive

A

33%

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18
Q

is the GI blood system parallel or series components?

A

both parallel and series components

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19
Q

advantages of having both parallel and series components

A

allows for regulation of blood flow to individual organs

Liver is exposed to all substances

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20
Q

what is microcirculation?

A

describes the high capillary density

large amount of fenestrated capillaries with enormous pore area for water and solute exchange

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21
Q

Sympathetic innervation resulting in decreased blood flow creates

A

an accumulation of metabolic products allows blood flow to return to normal

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22
Q

there is no direct parasympathetic innervation to the splanchnic circulation but,

A

PNS stimulation to each organ, PNS increases GI motility and secretion, increase in metabolism which indirectly increases blood flow

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23
Q

venous drainage in the splanchnic circulation

A

venous drainage from each organ empties into the portal vein and then perfuses in the liver

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24
Q

series component of the splanchnic circulation

A

the venous drainage

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25
the 3 major arteries compose the
parallel circulation part of the splenic circulation
26
describe the cephalic phase stimulation
begins before any food is ingested and is stimulated by sight, smell and tase or thought of food
27
cephalic pathway and mediator | how much of the total secretions does that cephalic phase account for?
pathway - direct vasovagal, gastrin - releasing peptide mediator - acetylcholine 30% of secretions
28
gastric pathway and mediator | how much of the total secretions does that gastric phase account for?
pathway - vasovagal intramural g cell stimulation mediator - gastrin 50% of secretions
29
describe the gastric phase stimulation
begins when food arrives in the stomach, stimulation distention, amino acids, protein digestion products
30
intestinal pathway and mediator | how much of the total secretions does that cephalic phase account for?
pathway - amino acid in blood mediator - gastrin 5 - 10 % of secretions
31
describe the intestine phase stimulation
longest and most important phase stimulation distention and protein digestion products
32
cephalic phase brain processed
the brain activates enteric neurons via parasympathetic preganglionic neurons traveling in the vagus, this causes a release in Ach which stimulates secretions in the salivary glands, parietal cells in stomach and enzyme secreting cells in the pancreas.
33
Secretions stimulated during cephalic phase
a large volume of salvia | a small volume of gastric acid, pepsin, and a small amount of pancreatic enzymes
34
how is the cephalic phase reinforced
by chewing
35
Swallowing Reflex is coordinated by
medullary swallowing center
36
Swallowing reflex voluntarily vs reflexive
initiated voluntarily movement, when it hits the back of the pharynx it is reflexive
37
3 phases swallowing reflex
oral, pharyngeal, esophageal
38
how many times a day do you shallow
600 times, 150 have to do with food others are for maintain of the oral cavity
39
sequence of event for swallowing?
The nasopharynx closes and, at the same time, breathing is inhibited. Largyngeal muscles contract to close the glottis and elevate the larynx. Peristalsis begins in the pharynx to propel the food bolus toward the esophagus. Simultaneously, the upper esophageal sphincter relaxes to permit the food bolus to enter the esophagus.
40
somatosensory receptors located near the pharynx are activated
and send signals via afferent neurons (V VII and IX nerves) to the swallowing center in the medulla (the nucleus ambiguous) which sends signals to the striated muscle of pharynx and upper third of esophagus which invites he involuntary swallowing reflect
41
the swallowing reflex oral phase voluntary
tongue pushes bolus back toward pharynx
42
the oral phase propels food from the mouth to the
pharynx
43
when the swallowing response is initiated efferent information is sent via
the glossopharyngeal, vagus and hypoglossal nerves
44
The upper 1/3 of the esophagus
is skeletal muscle
45
which part of the esophagus is both skeletal and smooth muscle
the middle 1/3
46
The lower 1/3 of the esophagus
is smooth muscle
47
ANS innervation of the esophagus regulates
glandular secretion, blood vessel caliber, and the activity of the muscles
48
PNS in the esophagus
PNS innervation via nucleus ambigus and dorsal motor nucleus of the vagus
49
SNS in the esophagus
SNS innervation from sympathetic chain
50
The UES and LES are ______ at rest
closed, they must relax when we want food to pass through them
51
Pharyngeal Phase Reflexive begins when
receptors are stimulated from the oral phase | the nasopharynx and trachea are blocked, and the UES opens
52
how is the nasopharynx blocked
soft palate pulled up to prevent reflux into the nasopharynx
53
how is the trachea blocked
epiglottis moves to cover opening to the larynx and the lynx moves up against epiglottis to prevent food from entering the trachea
54
UES in the pharyngeal phases
the UES relaxes and opens and the pharynx contraction allows food to enter the esophagus
55
During the pharyngeal phase of swallowing, respiration is
reflexly inhibited
56
which nerves are important during the pharyngeal phase of swallowing
glossopharyngeal and vagus
57
Bolus transfer
the tongue first thrust up and back and the nasopharynx will close, soon after the larynx elevates and then the airway closes and the UES opens and the phyynx will contract as the bolus enters the esophagus, the airway remains closed and the larynx xis elevated
58
Esophageal Phase begins
when food enters the esophagus
59
Esophageal Phase UES
will close to prevent food reflux back into the pharynx
60
Primary peristaltic wave
``` Propels bolus down esophagus toward LES (primary swallow). LES relaxes (receptive relaxation) with initiation of peristaltic wave, remains open 5-10 seconds, and contracts as bolus passes into stomach ```
61
Secondary peristalsis is controlled by
enteric nervous system
62
Secondary peristalsis is initiated by
esophageal distension if primary wave does not clear all the food
63
what develops behind the bolus in the esophagus
high pressure
64
gastric secretion cephalic phase
Parasympathetic action potentials are carried by the vagus nerve to the stomach where enteric neurons are activated causing the release of ACH
65
what does ACh stimulate in the cephalic phase
parietal cells to secrete HCl, ECL(enterochromaffin) cells to secrete histamine and G cells to secrete gastrin
66
where are enteric neurons found?
the lining of the stomach
67
cephalic phase is most
neurocrine regulated

PSIO EXAM 3 (8 decks)

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