Gastric motility Flashcards

1
Q

What is gastroparesis?

A

Decreased gastric motility (NOT a total shut down)

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2
Q

What is the migrating motor complex?

A

GI motor activity that starts in the stomach, and sweeps over the upper GI tract about every 90 minutes

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3
Q

What happens to the migrating motor complex during the fed state?

A

No longer migrating–constant motor activity

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4
Q

What are the three general types of GI motor activity?

A

Storing
Churning
Emptying

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5
Q

What causes the storing effect of the GI tract?

A

Tonic contractions

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6
Q

What are the two steps of gastric storing/filling?

A

Receptor relaxation

Gastric accommodation

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7
Q

What happens during the receptive relaxation phase of gastric storing? (2)

A

Relaxation of LES and stomach in anticipated by food

Rise in gastric volume, without change in pressure

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8
Q

What is the innervation of receptive relaxation reflex of the stomach?

A

Vagus

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9
Q

What initiates the receptive relaxation of the stomach?

A

Swallowing

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10
Q

What is the signalling used in receptive relaxation to relax the LES?

A

Non Cholinergic and nonadrenergic (NO mediated)

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11
Q

What happens in gastric accommodation?

A

Stomach relaxation in response to gastric filling

Dilation of fundus

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12
Q

What primarily regulates gastric accommodation? What modulates it?

A

ENS

Vagus

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13
Q

What happens to volume/pressure in gastric accommodation?

A

Increase in volume without increase in pressure (just like the bladder)

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14
Q

What are the three parts of gastric churning?

A

Propulsion
Retropulsion
Grinding

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15
Q

What is propulsion part of gastric churning?

A

Movement of stomach contents against the pyloric region

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16
Q

What happens to the pyloric sphincter during gastric churning?

A

Shuts down

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17
Q

What initiates the propulsion part of gastric churning?

A

Pacemaker cells near the greater curvature of the stomach

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18
Q

What is retropulsion part of gastric churning?

A

Pulverization and shearing of food particles by contractions

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19
Q

What is the overall goal of gastric churning?

A

Increased surface area of food

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20
Q

What happens in the grinding phase of gastric churning?

A

Food is trapped in the antrum

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21
Q

When do particles larger than 2 mm pass into the duodenum?

A

Interdigestive period (2 hours later)

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22
Q

The rate of gastric emptying is dependent on what?

A

The content of ingested material

23
Q

What happens to rate of gastric emptying with increasing protein and fat?

A

Lowers rate of emptying

24
Q

What controls the rate of gastric emptying?

A

Neuronal and hormonal control

25
Q

What three hormones play a role in gastric emptying?

A
  1. Secretin
  2. CCK
  3. Gastrin
26
Q

What are the four NTs utilized in gastric emptying?

A

Ach
NO
5HT
VIP

27
Q

HCl in the duodenum stimulates what hormone to be secreted? Result?

A

Secretin = impaired gastric emptying, increase HCO3 production from the pancreas

28
Q

Fat in the duodenum primarily stimulates what hormone to be secreted? Result?

A

CCK –impaired gastric empyting

29
Q

Protein in the stomach stimulates what hormone to be secreted? Result?

A

Gastrin– impaired gastric emptying

30
Q

Duodenal distension in the duodenum stimulates what? Result?

A

ENS–impaired gastric emptying

31
Q

Vagal stimulation in the duodenum stimulates which three neurotransmitters that impair gastric emptying?

A

Ach, opioid, 5HT = impaired gastric emptying

32
Q

What are the four targets of CCK?

A

Gallbladder
Pancreas
Stomach
Sphincter of Oddi

33
Q

What is the effect of CCK on the gallbladder?

A

Contraction

34
Q

What is the effect of CCK on the pancreas?

A

Acinar secretion

35
Q

What is the effect of CCK on the the stomach?

A

Reduced emptying

36
Q

What is the effect of CCK on the sphincter of Oddi??

A

Relaxation

37
Q

Gastroparesis is frequently associated with what?

A

Impairments of the pyloric region or pyloric sphincter itself (DM neuropathy/ infantile pyloric stenosis)

38
Q

What are the events involved in emesis?

A

Afferent fibers activated, which trigger the vomiting center, causing a reverse wave of peristalsis

39
Q

What is the stimulus for an emetic response?

A

Irritation of the GI mucosa

40
Q

What are the nerve fibers activated in emesis?

A

Afferent fibers

41
Q

What is the purpose of increased saliva prior to emesis?

A

Lubricates
Increases pH
Mucin protection

42
Q

The emetic response is coordinated by what nerve?

A

Vagal afferents and emetic center of the brain

43
Q

What is the purpose of secondary peristalsis in emesis?

A

Returns esophageal material back to the stomach

44
Q

What are the two stimuli for secondary peristalsis?

A

Stretch and lower pH

45
Q

What are the four key neurotransmitters for sensory information from the gut to be relayed back to the CNS?

A

5-HT, Ach, histamine, and D2

46
Q

What muscarinic receptors are located in the chemoreceptive trigger zone?

A

M1

47
Q

Motion sickness is mediated through what two receptors on the cerebellum?

A

Histamine and Ach

48
Q

Why can uncontrolled DM lead to gastroparesis?

A

Neuropathy

49
Q

What is the key neurotransmitter in the intestines?

A

5HT

50
Q

What happens in retching?

A

occurs when the upper esophageal sphincter does not relax and the contents of the stomach are not expelled

51
Q

What are the three receptors in the chemoreceptor trigger zone (which stimulates the emetic center of the brain)?

A

5HT, D2, M1

52
Q

What are the neurotransmitter receptors on the NTS (which stimulates the emetic center of the brain)?

A

5HT
D2
M1
H1

53
Q

Vagal stimulation in the duodenum stimulates which two hormones that promote gastric emptying

A

NO, VIP = promotes gastric emptying