14 - GI Anatomy and Histology Flashcards Preview

GI / Hepatology > 14 - GI Anatomy and Histology > Flashcards

Flashcards in 14 - GI Anatomy and Histology Deck (57)
1

Motility

Movements of the bowel that influence the transport of luminal contents

2

Ingestion

Act of taking food into the mouth

3

Mastication

Chewing food and moistening it with saliva

4

Deglutition

Swallowing

5

Peristalsis

Oral contraction and anal relaxation, which is propulsive

6

Secretion

Exocrine to lumen of gut, endocrine to blood

7

Digestion

Breakdown of ingested macromolecules into absorbable smaller subunits

8

Absorption

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

9

Storage

Temporary holding of ingested contents

10

Elimination

Getting rid of indigestible material

11

Sphincters of the gut

Upper Esophageal
Lower Esophageal
Pyloric
Iliocecal
Internal Anal
External Anal

12

Gut Wall - Luminal

Mucosa:
Epithelium
Lamina propria
Muscularis mucosa

13

Gut Wall - Middle Layer

Submucosa:
Submucosal plexus

14

Gut Wall - Basal

Muscularis Externa:
Inner circular muscle
Outer longitudinal muscle
Myenteric Plexus

15

Gut Wall - Non-retroperitoneal parts

Adventitia:
Serosa

16

Esophagus - To resist abrasion

Stratified squamous nonkeritanized epithelium

17

Stomach - To digest

Simple columnar epithelium

18

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

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

19

Upper esophagus - Muscularis externa

Mostly striated

20

Middle esophagus - Muscularis externa

Mix of striated and smooth

21

Lower esophagus - Muscularis externa

Mostly smooth

22

Regions of the stomach

Lower esophageal sphincter
Fundus
Body
Antrum
Pylorus
Duodenum

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

23

Fundic region

Rises above the entrance of the esophagus.
Contains air very often.

24

Body/corpus

Large region into which food is delivered.

25

Antrum

Different
Separated from duodenum by pyloric sphincter.

26

Oxyntic region of the stomach

Corpus + Fundus
Makes HCl
Makes pepsinogen
Contains parietal cells
Contains chief cells

27

Parietal Cells

Make HCl
Make Intrinsic Factor

28

Chief Cells

Make Pepsinogen

29

HCl

Acid!

30

Intrinsic Factor

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

Pepsinogen

Pepsin precursor

32

Pyloric region

Antrum
Makes Gastrin
Makes mucus pepsinogen
Contains G cells
Contains Mucous cells

33

Gastrin

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

34

Mucus pepsinogen

Provides protection of mucosa from HCl

35

G Cells

Produce gastrin if stimulated by alkaline environment or nerve activation.

36

Mucous Cells

Produce mucous pepsinogen

37

Cells in the stomach

Surface mucous epithelial cells
Mucous neck cells
Parietal cells
Chief cells
Endocrine cells

38

Surface Mucous Cells

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

39

Mucous neck cell

Stem cells to regenerate lost surface cells

40

Parietal cell

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

41

Chief cell

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

42

Endocrine cell

Scattered through the glands

43

Components of a gastric gland

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

44

What do parietal cells store?

MEMBRANE!!

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

45

What allows a parietal cell to secrete acid?

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

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

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

47

What effects does stimulation of a parietal cell have?

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

48

Pepsin

Digestive enzyme

49

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

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

50

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

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

51

Enteroendocrine Cells

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

GI Peptides

Involved in endocrine, paracrine and neurocrine signaling

53

Cholecystokinin (CKK)

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

54

Secretin

First hormone ever discovered
Promotes bicarb secretion from the pancreas, helps deal with the acid

55

Glucose-dependent Insolinotropic Peptide (GIP)

Promotes insulin release

56

Glucagon

Opposes insulin and promotes glycogenolysis

57

3 Secretogogues stimulating parietal cell acid secretion

Direct pathway - ACh from nerves, Gastrin, Histamine

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

Gastrin? I don't know...