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Physiology > GI I > Flashcards

GI I Flashcards

1
Q

What are the three systems that innervate the GI tract?

A

Symp
Parasymp
Enteric nervous system

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2
Q

What is the enteric nervous system? What is it regulated by?

A

Nervous system located entirely within the GI tract, regulated by the PNS and SNS

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3
Q

What are the intrinsic neurons to the GI tract from?

A

Enteric

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4
Q

What are the four types of ENS neurons?

A
  1. Motor neurons
  2. Sensory
  3. Associative neurons
  4. Intestinofugal neurons
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5
Q

What are the three functions of the sensory neurons in the ENS? Which type of stimulation is the most important?

A

Nocioceptive
Mechanoreceptive
Chemoreceptive

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6
Q

What do the motor neurons of the ENS regulate? (4)

A

Smooth muscle contraction
Vasodilation (promotes)
Water and electrolytes
Hormones

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7
Q

Symp promotes or inhibits GI function?

A

Inhibits

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8
Q

Parasymp promotes or inhibits GI function?

A

Promotes

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9
Q

What is the function of associative neurons of the GI system?

A

Interneurons between one group of neurons to the next

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10
Q

True or false: the GI tract can function independently of the CNS

A

True, but it functions better with para and symp innervation

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11
Q

What are the ways that the PNS and SNS can regulate GI tract function?

A

Direct synapse with smooth muscle

Synapse with ENS

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12
Q

What PNS ganglion terminates on the ENS: pre or postganglionic? What about for SNS?

A

Preganglionic for PNS

Postganglionic for SNS

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13
Q

What is the function of Ach on the PNS/SNS/ENS of the GI system? (3)

A

Vasodilation
Increased secretions
Smooth muscle contraction

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14
Q

What are the function of NE on the PNS/SNS of the GI system? (3)

A

Vasoconstriction
Inhibit smooth muscle contraction
Decreased secretions

(excitatory)

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15
Q

What is the function of 5HT on the ENS in the GI system?

A

Induces vasodilation
Induces smooth muscle contraction
Stimulate secretion

(excitatory)

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16
Q

What is the function of dopamine on the ENS in the GI system?

A

Inhibit ENS neuronal firing (inhibitory)

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17
Q

What is the function of NO on the ENS of the GI system?

A

Smooth muscle relaxation (inhibitory)

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18
Q

What is the function of VIP on the ENS in the GI system?

A

Smooth muscle relaxation (inhibitory)

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19
Q

What are the three key regulators of GI smooth muscles? Which stimulate, and which inhibit GI contractions?

A
  1. Ach (stimulate)
  2. VIP (inhibit)
  3. NO (inhibit)
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20
Q

What is the defining characteristic of the smooth muscle electrical potential?

A

has a BER (slow wave)

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21
Q

What are the four types of GI motor activities?

A
  1. Segmental (mixing)
  2. Peristaltic (moving)
  3. Reverse peristaltic (Storing)
  4. Migrating motor complex
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22
Q

What are segmental contractions?

A

Squishing back and forth (like a toothpaste tube). Used for mixing

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23
Q

What is peristaltic contraction?

A

Wave of contractions that moves in a direction

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24
Q

What are the neurotransmitters that are needed in peristaltic contractions (upstream and downstream of the bolus)?

A

Ach upstream of bolus

NO
VIP downstream

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25
Q

What is the migrating motor complex?

A

The wave of activity to move food down the GI tube that occurs about every 90 minutes

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26
Q

What happens to the migrating motor complex when a meal is introduced?

A

Disrupted

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27
Q

Where is the GI tract under voluntary control? (3)

A

Upper 1/3 of the esophagus is striated muscle

Upper esophageal sphincter

External anal sphincter

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28
Q

What are the six sphincter sites in the GI tube?

A
  1. Upper esophageal
  2. Lower esophageal
  3. Pyloric
  4. Ileocecal
  5. Internal anal
  6. External anal
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29
Q

Blood from the GI tract is absorbed via what vein to carry it to the liver?

A

Hepatic portal vein

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30
Q

How is the blood supply set up in the GI tract villus? What is the consequence of this if blood supply to the villi is compromised?

A

Counter-current–necrosis is thus easier

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31
Q

What is postprandial hyperemia?

A

Increased blood flow following a meal that occurs in a stepwise fashion

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32
Q

The flow of blood through the GI system is regulated by what?

A

Muscularis layers and through the villi and submucosal

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33
Q

How long is vasodilation maintained following a meal?

A

2-4 hours

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34
Q

What is the neurotransmitter used to decreased blood flow? Receptor?

A

NE

alpha adrenergic receptor

35
Q

Non-bilious emesis =?

A

Not yet reached bile duct

36
Q

Patient’s with pyloric stenosis are deficient of what neurotransmitter at that site?

A

NO

37
Q

What are the four major factors that increase blood flow to the GI tract?

A
  1. PNS
  2. Neurotransmitters (e.g. VIP)
  3. Hypoxia
  4. Hyperosmolarity
38
Q

What is the outermost layer of the GI tract, made up primarily of CT and covered by squamous epithelial cells?

A

Serosa

39
Q

What is the just beneath the serosa, and is composed of longitudinal and circular smooth muscle layers?

A

Muscularis

40
Q

Neurons the innervate the muscularis regulate what action?

A

Peristalsis

41
Q

What is the layer beneath the mucosa? What does it contain?

A

Submucosa, composed of blood vessels, glands, and CT

42
Q

What are the components of the mucosa?

A

Lamina propria and lamina muscularis

43
Q

What is the lamina propria composed of?

A

capillaries, neurons, and immune cells

44
Q

What is the lamina muscularis composed of?

A

layer of smooth muscle that helps coordinate GI motility

45
Q

In general, the SNS (BLANKS) GI activity

A

Inhibits

46
Q

In general, the PNS (BLANKS) GI activity

A

Activates

47
Q

What are the two ways the the SNS affects the GI tract?

A
  1. Indirectly by innervating ENS neurons

2. DIrectly innervate GI smooth muscle,endocrine, and secretory cells

48
Q

What are the two ways the the PNS affects the GI tract?

A
  1. Indirectly modulate GI function via ENS

2. Directly innervate specific cells of the GI tract with postganglionic fibers

49
Q

What are associative neurons (interneurons) of the ENS?

A

specialized neurons that are used to communicate information between ENS neurons

50
Q

What do the extrinsic neurons of the ENS sense?

A

Nocioception
Mechanoception
Chemoception

51
Q

What are the three paracrine regulators of the GI tract?

A
  1. Prostaglandins
  2. Histamine
  3. Somatostatin
52
Q

What is the source and target of prostaglandins in the GI tract?

A

Source: Stomach and intestines/immune cells

Target: same

53
Q

What is the action of prostaglandins on the GI tract? (blood flow? Acid? Mucus? Motility? Fluids?)

A 
Increase blood flow
Decreased acid
Increase mucus
Increase motility
Increase fluid secretion
54
Q

What is the source and target of histamine in the GI tract?

A

Source: Stomach and intestines/immune cells

Target: same

55
Q

What is the action of histamine on the GI tract? (acid? Fluid?)

A

Increase acid secretion

Increased fluid secretion

56
Q

What is the target and source of somatostatin in the GI tract?

A

Source: stomach, duodenum, pancreatic cells

Target: Stomach and intestines

57
Q

What is the action of somatostatin on the Gi tract? (Acid? Fluid absorption? Smooth muscle contraction?)

A

Decrease acid secretion
Increase fluid absorption
Decrease smooth muscle contraction

58
Q

Blood flow to and from the GI tract is known as what?

A

Splanchnic circulation

59
Q

What is the vein that delivers blood from the liver to the body?

A

Hepatic vein

60
Q

What are the key molecules that increase blood flow?

A

Ach
CO2
Hyperosmolarity
VIP

61
Q

What is the major vasoconstrictor of the GI tract?

A

NE

62
Q

What is the effect of NE on the action potential wave of GI muscles?

A

Hyperpolarizes membranes, making

63
Q

What are the three general GI movements?

A

Mixing
Moving
Storing

64
Q

What are reverse peristaltic contractions?

A

Storing contractions seen in the stomach and colon that permit retrograde movement of material

65
Q

What is the migrating motor complex?

A

is a wave of contractility that sweeps over the GI tract that is regulated by multiple stimuli, and occurs even in the absence of food

66
Q

What hormone has been shown to play a role in regulating and initiating the MMC?

A

Motlin

67
Q

What are the two stimuli that stimulate contractions in the GI tract?

A

Ach

Stretch

68
Q

What two sphincters of the GI tract are under voluntary control?

A

Upper esophageal

Lower rectal

69
Q

The key regulators which relax sphincter smooth muscle, resulting in a dilated sphincter, are what?

A

NO and VIP

70
Q

What does the upper esophageal sphincter separate?

A

Pharynx and upper esophagus

71
Q

What does the lower esophageal sphincter separate?

A

Esophagus and stomach

72
Q

What does the pyloric sphincter separate?

A

Stomach and duodenum

73
Q

What does the ileocecal sphincter separate? What causes it to open/close?

A

Ilium and the cecum
Opens with distension of the ileum

Ascending colon distention causes contraction

74
Q

Both the ENS stimulatory pathways and inhibitory pathways are within the same branch of the ANS. Which branch (parasymp or symp)?

A

Parasympathetic

75
Q

What allows the External anal sphincter to open?

A

Voluntary and involuntary relaxation of the sphincter

76
Q

What keeps the External anal sphincter to closed usually?

A

Involuntary reflex

77
Q

What does peptide YY come from, and what does it do?

A

from the ileum, and decreases enzyme and fluid secretion from the pancreas

78
Q

Where does secretin come from, and what does it do?

A

from the duodenum, and causes the stomach and pancreas to:

  1. Increase HCO3
  2. Decrease acid secretion
  3. Delay gastric empyting
79
Q

Where does somatostatin come from, and what is its target?

A

From the stomach, duodenum, and pancreas

Target = Stomach, intestines, liver

80
Q

What is the effect of somatostatin on acid secretion?

A

Decreases

81
Q

What is the effect of somatostatin on fluid absorption?

A

Increases

82
Q

What is the effect of somatostatin on smooth muscle contraction?

A

Decreases

83
Q

What is the effect of somatostatin on secretions in general?

A

Decreases

84
Q

What is the effect of somatostatin on bile flow?

A

Decreases

Physiology (75 decks)

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