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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
What is the migrating motor complex?
The wave of activity to move food down the GI tube that occurs about every 90 minutes
26
What happens to the migrating motor complex when a meal is introduced?
Disrupted
27
Where is the GI tract under voluntary control? (3)
Upper 1/3 of the esophagus is striated muscle Upper esophageal sphincter External anal sphincter
28
What are the six sphincter sites in the GI tube?
1. Upper esophageal 2. Lower esophageal 3. Pyloric 4. Ileocecal 5. Internal anal 6. External anal
29
Blood from the GI tract is absorbed via what vein to carry it to the liver?
Hepatic portal vein
30
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?
Counter-current--necrosis is thus easier
31
What is postprandial hyperemia?
Increased blood flow following a meal that occurs in a stepwise fashion
32
The flow of blood through the GI system is regulated by what?
Muscularis layers and through the villi and submucosal
33
How long is vasodilation maintained following a meal?
2-4 hours
34
What is the neurotransmitter used to decreased blood flow? Receptor?
NE | alpha adrenergic receptor
35
Non-bilious emesis =?
Not yet reached bile duct
36
Patient's with pyloric stenosis are deficient of what neurotransmitter at that site?
NO
37
What are the four major factors that increase blood flow to the GI tract?
1. PNS 2. Neurotransmitters (e.g. VIP) 3. Hypoxia 4. Hyperosmolarity
38
What is the outermost layer of the GI tract, made up primarily of CT and covered by squamous epithelial cells?
Serosa
39
What is the just beneath the serosa, and is composed of longitudinal and circular smooth muscle layers?
Muscularis
40
Neurons the innervate the muscularis regulate what action?
Peristalsis
41
What is the layer beneath the mucosa? What does it contain?
Submucosa, composed of blood vessels, glands, and CT
42
What are the components of the mucosa?
Lamina propria and lamina muscularis
43
What is the lamina propria composed of?
capillaries, neurons, and immune cells
44
What is the lamina muscularis composed of?
layer of smooth muscle that helps coordinate GI motility
45
In general, the SNS (BLANKS) GI activity
Inhibits
46
In general, the PNS (BLANKS) GI activity
Activates
47
What are the two ways the the SNS affects the GI tract?
1. Indirectly by innervating ENS neurons | 2. DIrectly innervate GI smooth muscle,endocrine, and secretory cells
48
What are the two ways the the PNS affects the GI tract?
1. Indirectly modulate GI function via ENS | 2. Directly innervate specific cells of the GI tract with postganglionic fibers
49
What are associative neurons (interneurons) of the ENS?
specialized neurons that are used to communicate information between ENS neurons
50
What do the extrinsic neurons of the ENS sense?
Nocioception Mechanoception Chemoception
51
What are the three paracrine regulators of the GI tract?
1. Prostaglandins 2. Histamine 3. Somatostatin
52
What is the source and target of prostaglandins in the GI tract?
Source: Stomach and intestines/immune cells Target: same
53
What is the action of prostaglandins on the GI tract? (blood flow? Acid? Mucus? Motility? Fluids?)
``` Increase blood flow Decreased acid Increase mucus Increase motility Increase fluid secretion ```
54
What is the source and target of histamine in the GI tract?
Source: Stomach and intestines/immune cells Target: same
55
What is the action of histamine on the GI tract? (acid? Fluid?)
Increase acid secretion | Increased fluid secretion
56
What is the target and source of somatostatin in the GI tract?
Source: stomach, duodenum, pancreatic cells Target: Stomach and intestines
57
What is the action of somatostatin on the Gi tract? (Acid? Fluid absorption? Smooth muscle contraction?)
Decrease acid secretion Increase fluid absorption Decrease smooth muscle contraction
58
Blood flow to and from the GI tract is known as what?
Splanchnic circulation
59
What is the vein that delivers blood from the liver to the body?
Hepatic vein
60
What are the key molecules that increase blood flow?
Ach CO2 Hyperosmolarity VIP
61
What is the major vasoconstrictor of the GI tract?
NE
62
What is the effect of NE on the action potential wave of GI muscles?
Hyperpolarizes membranes, making
63
What are the three general GI movements?
Mixing Moving Storing
64
What are reverse peristaltic contractions?
Storing contractions seen in the stomach and colon that permit retrograde movement of material
65
What is the migrating motor complex?
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
What hormone has been shown to play a role in regulating and initiating the MMC?
Motlin
67
What are the two stimuli that stimulate contractions in the GI tract?
Ach | Stretch
68
What two sphincters of the GI tract are under voluntary control?
Upper esophageal | Lower rectal
69
The key regulators which relax sphincter smooth muscle, resulting in a dilated sphincter, are what?
NO and VIP
70
What does the upper esophageal sphincter separate?
Pharynx and upper esophagus
71
What does the lower esophageal sphincter separate?
Esophagus and stomach
72
What does the pyloric sphincter separate?
Stomach and duodenum
73
What does the ileocecal sphincter separate? What causes it to open/close?
Ilium and the cecum Opens with distension of the ileum Ascending colon distention causes contraction
74
Both the ENS stimulatory pathways and inhibitory pathways are within the same branch of the ANS. Which branch (parasymp or symp)?
Parasympathetic
75
What allows the External anal sphincter to open?
Voluntary and involuntary relaxation of the sphincter
76
What keeps the External anal sphincter to closed usually?
Involuntary reflex
77
What does peptide YY come from, and what does it do?
from the ileum, and decreases enzyme and fluid secretion from the pancreas
78
Where does secretin come from, and what does it do?
from the duodenum, and causes the stomach and pancreas to: 1. Increase HCO3 2. Decrease acid secretion 3. Delay gastric empyting
79
Where does somatostatin come from, and what is its target?
From the stomach, duodenum, and pancreas Target = Stomach, intestines, liver
80
What is the effect of somatostatin on acid secretion?
Decreases
81
What is the effect of somatostatin on fluid absorption?
Increases
82
What is the effect of somatostatin on smooth muscle contraction?
Decreases
83
What is the effect of somatostatin on secretions in general?
Decreases
84
What is the effect of somatostatin on bile flow?
Decreases

Physiology (75 decks)

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