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FHB GI Material - Richie > L44&45 - GI Physiology - 3/3/15 > Flashcards

L44&45 - GI Physiology - 3/3/15 Flashcards

1
Q

The 4 physiological processes of GI include:

A

SMAD.

Secretion
Motility
Absorption
Digestion

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2
Q

What is the largest immune organ of the body?

A

GI tract

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3
Q

Into which segment of the GI tract are major enzymes secreted?

A

Duodenum

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4
Q

Which sphincter protects the airways?

A

UES: upper esophageal sphincter

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5
Q

Which sphincter protects against gastric reflux?

A

LES: lower esophageal sphincter

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6
Q

What sphincter controls the release of bile and pancreatic contents into the duodenum?

A

Sphincter of Oddi

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7
Q

What sphincter controls the release of stomach contents into the duodenum?

A

Pyloric sphincter

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8
Q

What sphincter controls the release of small intestinal contents, into the caecum?

A

Ileocecal sphincter

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9
Q

What sphincter(s) control the release of fecal matter?

A

Internal and external anal sphincters

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10
Q

The splanchnic circulation receives what % of cardiac output?

A

25%

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11
Q

What are the 3 major arteries that supply the abdominal organs?

A

Celiac artery
SMA
IMA

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12
Q

Where do hepatic veins drain?

A

Inferior vena cava

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13
Q

Where does the portal vein drain?

A

Liver

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14
Q

Do lipid soluble substances travel to the liver?

A

No, they don’t use the portal vein and go to liver. Instead they’re absorbed by lymphatics.

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15
Q

Where do lymphatics drain into systemic circulation?

A

Thoracic duct

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16
Q

Where is the thoracic duct?

A

L. subclavian vein

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17
Q

What are the 4 layers of the gut wall?

A
  1. Mucosa
  2. Submucosa
  3. Muscularis EXTERNA
  4. Serosa
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18
Q

What 3 layers compose the mucosa?

A
  1. Epithelium
  2. Lamina propria
  3. Muscularis mucosae
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19
Q

Gut epithelial cells are tied together via

A

tight junctions

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20
Q

What is the most abundant form of epithelial cells, that plays a role in digestion and absorption?

A

Absorptive ENTEROcytes

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21
Q

What cells release regulatory peptides and amines?

A

Enteroendocrine cells (EEC’s)

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22
Q

What specialized mucosal cells produce H+ protons?

A

Gastric mucosal cells

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23
Q

What cells produce mucin?

A

Mucin-producing cells. DUH!

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24
Q

What type of epithelial cells line the esophagus?

A

Squamous

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25
Q

What type of epithelial cells line the intestine, and specialize in absorption?

A

Columnar

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26
Q

What theory explains the short lifespan of villi epithelial cells?

A

Since there is an increased risk of mutation, better to get rid of them

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27
Q

Where are proliferative cells located in the intestinal villi?

A

Cryptes - zone of intestinal stem cells

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28
Q

What is considered the “unit of absorption”?
A. Vilus
B. Microvillus

A

A. Villus

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29
Q

What composes the “brush border”?
A. Villi
B. Microvilli

A

B. Microvilli

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30
Q

Mucosal folds, villi, and microvilli increase SA of intestine by

A

600 fold

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31
Q

Name a disease that decreases SA of absorptive intestinal surface

A

Celiac’s disease

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32
Q

Microvillar membrane (MM) has a high % of

A

Cholesterol and sphingolipids

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33
Q

What mucosal layer is between the epithelium and the muscularis mucosae?

A

Lamina propria

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34
Q

What mucosal layer contains lymph vessels, nerves, nodes, and capillaries?

A

Lamina propria

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35
Q

Meissner’s plexus is also known as

A

The submucosal plexus

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36
Q

What 2 layers sandwich the submucosal (Meissner’s) plexus?

A

Submucosa & Circular smooth muscle

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37
Q

What 2 layers sandwich the Myenteric plexus?

A

Circular smooth muscle & longitudinal smooth muscle

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38
Q

What 2 plexi compose the little brain of gut?

A

Submucosal (Meissner’s) and the myenteric plexus

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39
Q

Which muscle layer adjusts the diameter of the tract?

A

Circular smooth muscle

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40
Q

What layers compose the muscular externa

A

Circular and longitudinal muscle layer

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41
Q

Ever hear of Auerbach’s plexus?

A

aka myenteric plexus

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42
Q

What secretes viscous fluids to reduce friction of the GI tract?

A

Serosa

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43
Q

Name the 3 principle regulatory systems of GI

A
  1. Neural
  2. Endocrine
  3. Paracrine
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44
Q

What’s the post-prandial period?

A

Intense GI activity after meal

45
Q

What are the sensor cells of the GI system?

A

Entero-Endocrine cells (EEC)

46
Q

What 2 types of EEC’s are there?

A

Open (for SENSING) and closed.

The apex of OPEN EEC’s are in contact with the lumen, and the base secrete hormones into the blood stream.

47
Q

Are ECL cells open or closed type EEC?

A

Closed

48
Q

G cells are EEC’s that secrete

A

gastrin

49
Q

gastrin from G-cells stimulates secretion by

A

ECL and parietal cells

50
Q

T/F: a signal that travels from gut to CNS brain is PARACRINE.

A

False. Endocrine. Paracrine is not transported via circulation

51
Q

What’s an ECL?

A

enterochromaffine-like cell. It’s a specialized EEC (closed) that regulates contractile activity of smooth muscle in GI.

52
Q

Name a paracrine signal secreted by ECL

A

histamine

53
Q

5-HT (seratonin) is paracrine or endocrine, in today’s lecture?

A

Paracrine

54
Q

Cholecystokinin is both

A

Paracrine - acts on local nerves

Autocrine - acts on pancreas

55
Q

Dietary protein and lipid enters DUODENUM, promoting secretion of

A

Cholecystokinin

56
Q

What receptor binds cholecystokinin?

A

CCK1

57
Q

Allergen in gluten

A

gliadin

58
Q

Secretin is para or endo

A

BOTH

59
Q

I-cells of duodenum secrete

A

CCK

60
Q

S-cells of duodenum secrete

A

secretin

61
Q

K-cells of duodenum and jejunum secrete

A

GIP (gluco-insulinotropic peptide)

62
Q

K-cells secrete GIP in response to

A

fatty acid and glucose

63
Q

S-cells secrete secretin in response to

A

H+ in duodenum

64
Q

I-cells secrete CCK in response to

A

FA and hydrolyze protein

65
Q

G-cells secrete gastrin in response to

A

small peptides and AA’s

66
Q

Gastrin ultimately promotes 3 things:

A

H+ secretion from parietal cells
Histamine secretion from ECL cells
Growth of gastric mucosa

67
Q

CCK promotes

A

DECREASED gastric emptying and H+ secretion.
DECREASED food intake.
INCREASED pancreatic enzyme secretion
INCREASED contraction of gallbladder

(“HOLD ON! Let me process all this food!”

68
Q

Secretin promotes

A

Secretion of H20 and HCO3- from pancreatic duct

69
Q

GIP promotes

A

insulin secretion from pancreas

70
Q

PYY is para or endo?

A

Both

71
Q

GLP1/2 is para or endo?

A

Both

72
Q

Name 4 hormones that are both para and endo:

A
  1. CCK
  2. Secretin
  3. PYY
  4. GLP1/2
73
Q

L-cells from intestine secrete

A

PYY and GLP-1/2

74
Q

PYY secretion is stimulated by

A

FA, gluc, hydrolyzed protein

75
Q

GLP-1/2 secretion is stimulated by

A

same as PYY

FA, gluc, hydrolyzed protein

76
Q

PYY promotes

A

DECREASED (ALL):

  1. gastric emptying and H+ secretion
  2. pancreatic secretion
  3. intestinal motility
  4. food intake
77
Q

GLP-1/2 promotes

A

glc homeostasis

Increased epithelial cell proliferation

78
Q

The gut brain is extrinsic or intrinsic NS?

A

intrinsic ns

79
Q

T/F: salivary gland secretion is controlled by CNX

A

False

80
Q

What are the 2 divisions of the EXTRINSIC neural regulation of GI

A

Parasympathetic and sympathetic

81
Q

What innervates the esophagus, stomach, 1st part of the intestine, cecum, and proximal colon?

A

CN X (extrinsic parasymp. innervation)

82
Q

What innervates distal colon and anorectal region?

A

Pelvic nerves (extrinsic parasymp. innervation)

83
Q

What % of CNX is afferent? Efferent?

A

75% afferent. 25% efferent.

84
Q

What type of reflexes in CNX use both afferents and efferents at once?

A

“Vagovagal” reflexes

85
Q

Sympathetics generally _______ GI smooth muscle function?

A

inhibit

86
Q

EXCEPTION: sympathetics _______ sphincter muscles

A

constrict

87
Q

Parasympathetic ________ fibers are longer and synapse ________ the GI tract

A

preganglionic, outside

88
Q

Name 3 sympathetic ganglia that serve the GI tract

A
  1. Celiac
  2. Superior mesenteric
  3. Inferior mesenteric
89
Q 
Post-ganglionic nerves that contract GI sphincters release:
A. ACh
B. Substance P
C. VIP
D. Norepinephrine
A

D. Norepinephrine (adrenergic)

We’re talking sympathetics here.

90
Q

50% of these fibers are afferent, while 50% are efferent.

A

Sympathetic

91
Q

Challenge: what ganglion relays sympathetic innervation to the esophagus?

A

Superior cervical ganglion

92
Q

Which plexus lies between longitudinal and circular muscle layers?

A

Myenteric plexus

93
Q

T/F: ENS needs external innervation to react.

A

False. It can act autonomously. Thus little brain of gut.

94
Q

ENS can release:

A

Neurotransmitters, neuromodulators

95
Q

Two types of GI contraction

A

Phasic (periodic) or tonic (sustained tone)

96
Q

Esophagus, gastric antrum, and small intestine display what kind of contraction?

A

Phasic

97
Q

upper (orad) stomach, lower esophageal, ileocecal, and internal anal sphincters display what kind of contraction?

A

Tonic

98
Q

Slow waves are characterized by

A

Oscillating depol and repol
Don’t typically hit threshold
AP may occur on top of slow wave

99
Q

Slow wave frequency is 3/min in

A

stomach

100
Q

Slow wave frequency is 12/min in

A

duodenum

101
Q

Where do slow waves originate?

A

Interstitial cells of Cajal (ICC) - pacemaker cells of GI between longitudinal and circular muscle layers of muscular externa

102
Q

T/F: sub threshold slow waves produce contraction

A

TRUE, though weak. Tonic contractions are composed of sub-threshold waves

103
Q

What kind of contractions rely on AP that occur on top of slow waves?

A

Phasic contractions

104
Q

Are individual AP’s followed by separate muscular twitches in GI smooth muscle?

A

No! They summate into one long contraction.

105
Q

No forward movement of bolus for mixing.

A

Segmental contraction

106
Q

Orad to caudad contractions to propel chyme

A

Peristaltic contraction

107
Q

What NT is required for orad contraction

A

ACh and sP

108
Q

What NT is required for caudad relaxation

A

VIP and NO

FHB GI Material - Richie (8 decks)

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