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Practice Topics Exam 5 > GI Physiology 1 > Flashcards

GI Physiology 1 Flashcards

1
Q

Regulation of the GI system - Endocrine

A

Regulation that utilizes the blood to send wide spread signals throughout the body
Hormones released

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2
Q

Regulation of the GI system - Paracrine

A

Regulation that targets cells in close proximity (neighboring cells) and results in a more localized effect
Allows for localized communication

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3
Q

Regulation of the GI system - Neurocrine

A

Regulation that occurs when neurons innervate endocrine, vascular, or muscle cells and modulate their function

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4
Q

Regulation of the GI system - Autonomic Nervous System involves

A

PNS
SNS
ENS (enteric)

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5
Q

Regulation of the GI system - Key features of the enteric NS

A

Branch of the ANS
100 million neurons (equal to spinal cord)
Located entirely in GI
Regulated by local stimuli and PNS and SNS

There is communication btw the PNS and SNS with the ENS

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6
Q

ENS functions

A

ALL BY ITSELF! But, it will function better when it is communicating with the CNS and other branches of the ANS

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7
Q

ENS - gut brain axis

A

Communication between the ENS and the CNS
Involves communication by efferent and afferent neurons of the ANS that allow for fine tuning of the GI regulatory functions

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8
Q

PNS - afferents and efferents

A 
Afferents = nausea, distension, satiety 
Efferents = Stimulate motility, stimulate secretions, VD
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9
Q

SNS - afferents and efferents

A 
Afferents = pain
Efferents = Inhibit mobility, inhibit secretions, VC
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10
Q

ENS - what does it do

A 
Motility regulation
Secretory regulation
Mechanical sensation
Chemical sensation
Pain sensation
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11
Q

Neuronal innervation of the GI tract - Intrinsic ENS neurons

A

Motor neurons
Sensory neurons
Associative neurons (interneurons)
Intestinofungal neurons (regulate symp ganglia)

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12
Q

Neuronal innervation of the GI tract - Intrinsic ENS neurons - Motor neurons

A

Stimulate and inhibit smooth mm
VD
Regulate electrolyte and water secretion
Regulate secretion of hormones, electrolytes, water…

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13
Q

Neuronal innervation of the GI tract - Intrinsic ENS neurons - sensory neurons

A

Nociceptive neurons
Mechanoreceptive neurons
Chemoreceptive neurons

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14
Q

Neuronal innervation of the GI tract - Extrinsic ENS neurons

A

Sympathetic
Parasympathetic
Sensory input

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15
Q

Neuronal innervation of the GI tract - Extrinsic ENS neurons - Sympathetic

A

Motility inhibiting neurons
VC neurons
Secretomotor inhibiting neurons

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16
Q

Neuronal innervation of the GI tract - Extrinsic ENS neurons - Parasympathetic

A 
Motility stimulating
VD neurons
Secretomotor stimulating neurons
ENS inhibitory 
ENS excitatory
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17
Q

Neuronal innervation of the GI tract - Extrinsic ENS neurons - sympathetic input

A

nociceptive neurons
mechoceptive
chemoceptive

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18
Q

NT of the GI tract - NT of the PNS and SNS

A

Ach

NE

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19
Q

NT of the GI tract - NT of the PNS and SNS - Ach

A

VD
Inc secretions
Smooth mm contraction

Primary NT of the PNS - can be released by both pre and post PNS to stimulate GI

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20
Q

NT of the GI tract - NT of the PNS and SNS - NE

A

VC
Inhibit smooth mm contraction
Dec secretions

Primary NT of the SNS - inhibit GI

21
Q

NT of the GI tract - NT of the ENS

A 
Ach
Serotonin
Dopamine
Nitric Oxide
Vasoactive intestinal peptide
22
Q

NT of the GI tract - NT of the ENS - Ach

A

VD
Inc smooth mm contraction
Stimulate secretion

23
Q

NT of the GI tract - NT of the ENS - Serotonin

A

VD
Inc smooth mm contraction
Stimulate secretion (interneurons)

24
Q

NT of the GI tract - NT of the ENS - Dopamine

A

Inhibit ENS neuronal firing

25
Q

NT of the GI tract - NT of the ENS - NO

A

Smooth mm relaxation (vascular and GI)

26
Q

NT of the GI tract - NT of the ENS - VIP

A

Smooth mm relaxation (vascular and GI)

27
Q

GI motility - what is BER

A

Basal electrical rhythm or slow waves

Spontaneous oscillating de and re polarization waves that do not elicit a contraction

28
Q

GI motility - BER is initiated by

A

the interstitial cells of Cajal that serve as the pace packer cells and lie between the longitudinal and circular muscle

29
Q

GI motility - spike potentials are

A

rapid depolarization events that occur at the peak of the slow wave and elicit a contraction
Tension correlates with the spike potentials
In the absence of spike potentials, the cell is at rest

30
Q

GI motility - primary regulators of GI smooth mm

A

Ach (stimulate contraction)
VIP (inhibit contraction)
NO (inhibit contraction)

31
Q

GI motility - 4 types of GI motor activity

A 
Segmental contraction (mixing)
Peristaltic contractions (moving)
Reverse peristaltic contraction (storing and keeping empty)
Migrating motor complex (MMC - during interdigestive period)
32
Q

GI motility - Segmental contractions - describe

A

Toothpaste analogy
Intermittent spaced segments of contraction
All moves to middle and then there is a contraction in the middle of the tube and it all goes to outside - moves back and forth so you get mixing

33
Q

GI motility - motility within the GI tract is coordinated by

A

Regulators that promote smooth muscle contraction (Ach) and regulators that induce smooth mm contraction (NO, VIP)

Need to appreciate the upstream contraction and the downstream relaxation to allow directional motility in the GI tract

34
Q

GI motility - MMC - what is it

A

Migrating motor complex is a rhythmic motility pattern that occurs during the interdigestive period (between meals) approx every 90 min

35
Q

GI motility - MMC - purpose

A

To maintain directional movement of undigested contents

36
Q

GI motility - MMC - strongest contractions are in the

A

Upper GI tract (stomach, duodenum, jejunum) and fade in intensity in the ileum and colon

37
Q

Loss of function of the MMC can lead to

A

Inc colonization of bacteria in the upper GI tract

38
Q

GI motility - Also regulated by __ mm

A

Striated

  • Upper esophageal sphincter
  • Upper 1/3 of esophagus
  • External anal sphincter
39
Q

GI motility - directional movement is regulated by what? and name them

A 
Sphincters!
UES
LES
PS
IS
IAS
EAS
40
Q

GI motility - sphincters are ___ ____ mm and regulate ___ movements

A

Sphincters are specialized circular muscles and regulate antegrade and retrograde movements

41
Q

Blood supply of the GI tract

A

Splanchnic circulation
Receives about 30% of the CO when the body is at rest
This reservoir can be shunted though to other regions (during ex for example)

42
Q

Blood supply of the GI tract - Blood is delivered primarily by the ____
GI organs drain into the _____

A

Celiac and superior mesenteric arteries

The GI organs drain into the portal vein

43
Q

Blood supply of the GI tract - The portal venous system delivers blood to the ____

A

Liver!

So contents absorbed by the GI tract have to pass through the liver!

44
Q

Blood supply of the GI tract - factors that increase blood flow

A

8 fold inc in blood flow following a meal (postprandial hyperemia)
Sequential dilation of the GI tract (prox to distal)
Flow is regulated to muscularis layers and through villi and submucosa
VD is maintained for 2 to 4 hrs after the meal

PNS, NO, VIP, hormones like CCK, low oxygen, hyperosmolarity

45
Q

Blood supply of the GI tract - factors that decrease blood flow

A

SNS innervation of vascular smooth mm
- NE, alpha adrenergic receptors

Endocrine/paracrine regulation of vascular smooth mm

  • Somatostatin
  • Analogues of somatostatin can be administered to dec GI bleeding
46
Q

Some differences between the large and small intestine

A

Small intestine longer with larger apical area

Large intestine has no nutrient absorption and no villi

47
Q

Enteric bacteria - what is the pattern

A

As you move away from the stomach (to a less acidic environment) the population/amount of bacteria is greater
Greater at the colon than at the stomach

48
Q

Enteric bacteria - growth of GI bacteria

A

GI secretions (saliva, acid, fluid/electrolytes, bile)
Mucosal immunity
Intestinal motility
Pharmacological agents (antibiotics, CA chemo, immunosuppressants, motility inhibitors, acid inhibitors)

49
Q

Enteric bacteria - functions of intestinal bacteria

A

Nutrient metabolism and salvage
Xenobiotic and drug metabolism
Antimicrobial protection and suppression of pathogenic organisms
Immunomodulation and development of gut immune system

Practice Topics Exam 5 (13 decks)

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