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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
Q

the 3 major arteries compose the

A

parallel circulation part of the splenic circulation

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26
Q

describe the cephalic phase stimulation

A

begins before any food is ingested and is stimulated by sight, smell and tase or thought of food

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27
Q

cephalic pathway and mediator

how much of the total secretions does that cephalic phase account for?

A

pathway - direct vasovagal, gastrin - releasing peptide
mediator - acetylcholine
30% of secretions

28
Q

gastric pathway and mediator

how much of the total secretions does that gastric phase account for?

A

pathway - vasovagal intramural g cell stimulation
mediator - gastrin
50% of secretions

29
Q

describe the gastric phase stimulation

A

begins when food arrives in the stomach, stimulation distention, amino acids, protein digestion products

30
Q

intestinal pathway and mediator

how much of the total secretions does that cephalic phase account for?

A

pathway - amino acid in blood
mediator - gastrin
5 - 10 % of secretions

31
Q

describe the intestine phase stimulation

A

longest and most important phase stimulation distention and protein digestion products

32
Q

cephalic phase brain processed

A

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
Q

Secretions stimulated during cephalic phase

A

a large volume of salvia

a small volume of gastric acid, pepsin, and a small amount of pancreatic enzymes

34
Q

how is the cephalic phase reinforced

A

by chewing

35
Q

Swallowing Reflex is coordinated by

A

medullary swallowing center

36
Q

Swallowing reflex voluntarily vs reflexive

A

initiated voluntarily movement, when it hits the back of the pharynx it is reflexive

37
Q

3 phases swallowing reflex

A

oral, pharyngeal, esophageal

38
Q

how many times a day do you shallow

A

600 times, 150 have to do with food others are for maintain of the oral cavity

39
Q

sequence of event for swallowing?

A

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
Q

somatosensory receptors located near the pharynx are activated

A

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
Q

the swallowing reflex oral phase voluntary

A

tongue pushes bolus back toward pharynx

42
Q

the oral phase propels food from the mouth to the

A

pharynx

43
Q

when the swallowing response is initiated efferent information is sent via

A

the glossopharyngeal, vagus and hypoglossal nerves

44
Q

The upper 1/3 of the esophagus

A

is skeletal muscle

45
Q

which part of the esophagus is both skeletal and smooth muscle

A

the middle 1/3

46
Q

The lower 1/3 of the esophagus

A

is smooth muscle

47
Q

ANS innervation of the esophagus regulates

A

glandular secretion, blood vessel caliber, and the activity of the muscles

48
Q

PNS in the esophagus

A

PNS innervation via nucleus ambigus and dorsal motor nucleus of the vagus

49
Q

SNS in the esophagus

A

SNS innervation from sympathetic chain

50
Q

The UES and LES are ______ at rest

A

closed, they must relax when we want food to pass through them

51
Q

Pharyngeal Phase Reflexive begins when

A

receptors are stimulated from the oral phase

the nasopharynx and trachea are blocked, and the UES opens

52
Q

how is the nasopharynx blocked

A

soft palate pulled up to prevent reflux into the nasopharynx

53
Q

how is the trachea blocked

A

epiglottis moves to cover opening to the larynx and the lynx moves up against epiglottis to prevent food from entering the trachea

54
Q

UES in the pharyngeal phases

A

the UES relaxes and opens and the pharynx contraction allows food to enter the esophagus

55
Q

During the pharyngeal phase of swallowing, respiration is

A

reflexly inhibited

56
Q

which nerves are important during the pharyngeal phase of swallowing

A

glossopharyngeal and vagus

57
Q

Bolus transfer

A

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
Q

Esophageal Phase begins

A

when food enters the esophagus

59
Q

Esophageal Phase UES

A

will close to prevent food reflux back into the pharynx

60
Q

Primary peristaltic wave

A 
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
Q

Secondary peristalsis is controlled by

A

enteric nervous system

62
Q

Secondary peristalsis is initiated by

A

esophageal distension if primary wave does not clear all the food

63
Q

what develops behind the bolus in the esophagus

A

high pressure

64
Q

gastric secretion cephalic phase

A

Parasympathetic action potentials are carried by the vagus nerve to the stomach where enteric neurons are activated

causing the release of ACH

65
Q

what does ACh stimulate in the cephalic phase

A

parietal cells to secrete HCl, ECL(enterochromaffin) cells to secrete histamine and G cells to secrete gastrin

66
Q

where are enteric neurons found?

A

the lining of the stomach

67
Q

cephalic phase is most

A

neurocrine regulated

PSIO EXAM 3 (8 decks)

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