14 - GI Anatomy and Histology Flashcards

1
Q

Motility

A

Movements of the bowel that influence the transport of luminal contents

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2
Q

Ingestion

A

Act of taking food into the mouth

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3
Q

Mastication

A

Chewing food and moistening it with saliva

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4
Q

Deglutition

A

Swallowing

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5
Q

Peristalsis

A

Oral contraction and anal relaxation, which is propulsive

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6
Q

Secretion

A

Exocrine to lumen of gut, endocrine to blood

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7
Q

Digestion

A

Breakdown of ingested macromolecules into absorbable smaller subunits

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8
Q

Absorption

A

Transport of end products of digestion to blood and/or lymph

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9
Q

Storage

A

Temporary holding of ingested contents

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10
Q

Elimination

A

Getting rid of indigestible material

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11
Q

Sphincters of the gut

A
Upper Esophageal
Lower Esophageal
Pyloric
Iliocecal
Internal Anal
External Anal
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12
Q

Gut Wall - Luminal

A

Mucosa:
Epithelium
Lamina propria
Muscularis mucosa

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13
Q

Gut Wall - Middle Layer

A

Submucosa:

Submucosal plexus

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14
Q

Gut Wall - Basal

A

Muscularis Externa:
Inner circular muscle
Outer longitudinal muscle
Myenteric Plexus

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15
Q

Gut Wall - Non-retroperitoneal parts

A

Adventitia:

Serosa

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16
Q

Esophagus - To resist abrasion

A

Stratified squamous nonkeritanized epithelium

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17
Q

Stomach - To digest

A

Simple columnar epithelium

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18
Q

Basic plan of the gut wall layers (illustrated by esophagus)

A

Stratified squamous nonkeritanized epithelium (to resist abrasion)
Lamina propria
Muscularis mucosa (express lymph and fluid from the fluid in the lamina propria) - contains fenestrated blood vessels, the most permeable in the body.
Muscularis externa: Inner circulate & outer longitudinal

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19
Q

Upper esophagus - Muscularis externa

A

Mostly striated

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20
Q

Middle esophagus - Muscularis externa

A

Mix of striated and smooth

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21
Q

Lower esophagus - Muscularis externa

A

Mostly smooth

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22
Q

Regions of the stomach

A
Lower esophageal sphincter
Fundus
Body
Antrum
Pylorus
Duodenum

Also split into Orad and Caudad region, about halfway through the body.

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23
Q

Fundic region

A

Rises above the entrance of the esophagus.

Contains air very often.

24
Q

Body/corpus

A

Large region into which food is delivered.

25
Q

Antrum

A

Different

Separated from duodenum by pyloric sphincter.

26
Q

Oxyntic region of the stomach

A
Corpus + Fundus
Makes HCl
Makes pepsinogen
Contains parietal cells
Contains chief cells
27
Q

Parietal Cells

A

Make HCl

Make Intrinsic Factor

28
Q

Chief Cells

A

Make Pepsinogen

29
Q

HCl

A

Acid!

30
Q

Intrinsic Factor

A

The one component made by stomach completely vital for health.

Need it to digest Vitamin B12. Without IF, you get pernicious anemia and demyelination of the spinal cord. B12 deficiency.

31
Q

Pepsinogen

A

Pepsin precursor

32
Q

Pyloric region

A
Antrum
Makes Gastrin
Makes mucus pepsinogen
Contains G cells
Contains Mucous cells
33
Q

Gastrin

A

Stimulates the production of more HCl.
Stimulates growth of gastric mucosa
Produced in pyloric region of the stomach.

34
Q

Mucus pepsinogen

A

Provides protection of mucosa from HCl

35
Q

G Cells

A

Produce gastrin if stimulated by alkaline environment or nerve activation.

36
Q

Mucous Cells

A

Produce mucous pepsinogen

37
Q

Cells in the stomach

A
Surface mucous epithelial cells
Mucous neck cells
Parietal cells
Chief cells
Endocrine cells
38
Q

Surface Mucous Cells

A

Superficial lining of surface and beginning of the pit area of the gland
Defend stomach against HCl

39
Q

Mucous neck cell

A

Stem cells to regenerate lost surface cells

40
Q

Parietal cell

A
Oxyntic cells
Abundant surface area when secreting
Contains intracellular canaliculi & microvilli
MANY Mitochondria
Large
Complex cristae
41
Q

Chief cell

A
Secretes pepsinogen
Specialized for regulation of secreted protein
Abundant RER
Huge number of zymogen granules
Big Gogli
42
Q

Endocrine cell

A

Scattered through the glands

43
Q

Components of a gastric gland

A

Pit (SurfaceMucous Cells)
Neck (Parietal cells, Mucous Neck Cells, Stem Cells, Enteroendocrine cells)
Base (Chief Cells, Parietal Cells, Enteroendocrine Cells)

44
Q

What do parietal cells store?

A

MEMBRANE!!

In the resting state, there are tons of small tubulovesicles.
These will become microvilli by exocytosis

45
Q

What allows a parietal cell to secrete acid?

A

A H+/K+ pump!!
Trades hydrogen for potassium
Funded by ATP hydrolysis
Cl- exits through channels in luminal membrane. Meets up with H+ and forms HCl in the lumen.
Bicarb is made as a byproduct of reverse-combusting water and CO2. This bicarb exits into the interstitial space in exchange for Cl-.

46
Q

Once HCl is secreted by a parietal cell, what pH changes occur where?

A

Lumen is acidic
Blood is alkaline
Digestion - YAYYYY
CNS - sleepyyyyyy

47
Q

What effects does stimulation of a parietal cell have?

A

Adds membrane and H+/K+ ATPase to the parietal cell surface.

48
Q

Pepsin

A

Digestive enzyme

49
Q

What is needed for the conversion of pepsinogen to pepsin?!

A

Low pH!!

Once some is converted, though, Pepsin can catalyse other pepsinogen, so it quickly becomes autocatalytic.

50
Q

What happens to pepsin in an alkaline environment (Like in the duodenum)?!

A

It is irreversibly inactivated once it hits a pH > 3.5!!

51
Q

Enteroendocrine Cells

A

Secrete into the lamina propria
Secretion granules are basolateral, not apical
Respond to luminal, neural or endocrine signals

Polarized basolaterally
Golgi lies between nucleus and base of cell
Few to no apical granules
Microvilli may be sensory

52
Q

GI Peptides

A

Involved in endocrine, paracrine and neurocrine signaling

53
Q

Cholecystokinin (CKK)

A
Promotes gall bladder contraction.
Promotes secretion of pancreatic enzymes
Delays gastric emptying
Induces satiety
Trophic to pancreas and gall bladder.
54
Q

Secretin

A

First hormone ever discovered

Promotes bicarb secretion from the pancreas, helps deal with the acid

55
Q

Glucose-dependent Insolinotropic Peptide (GIP)

A

Promotes insulin release

56
Q

Glucagon

A

Opposes insulin and promotes glycogenolysis

57
Q

3 Secretogogues stimulating parietal cell acid secretion

A

Direct pathway - ACh from nerves, Gastrin, Histamine

Indirect pathway - Nerves act on enteroendocrine cell, affecting histamine.

Gastrin? I don’t know…