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Flashcards in Wk1 GI Phys Overview Deck (44)
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1

4 major layers of GI wall?

1. Mucosa

2. Submucosa

3. Muscularis Externa

4. Serosa

2

Three sub-layers of the GI mucosa:

1. Epithelium

2. Lamina propria

3. Muscularis mucosae

3

Primary component of the GI sub-mucoa:

submucus nerve plexus

4

Three sub-layers of the GI muscularis externa:

1. Circular muscle

2. Myenteric nerve plexus

3. Longitudinal muscle

5

Main difference between small intestine and colonic mucosa?

Small intestine has villi (increased surface area)

Colon is flat to lumen

6

Why such high rate of turnover in GI epithelial cells?

prevents accumulation of mutations due to toxin exposure

7

Organs with two layers of mucus:

stomach

colon

8

Organ with one layer of mucus:

small intestine

9

What protects protein core of mucus from proteases?

glycosylation

**carbohydrate side chains attract water to form gel

10

Exocrine digestive enzymes are secreted via?

zymogen granules

11

Zymogen docking and dumping stimulated by increase in which two substances?

cAMP

Ca2+

12

Small bowel overgrowth of bacteria causes increase in organic acid production and pulls water into lumen from the blood stream leading to:

osmotic diarrhea

13

Infection causing an excess secretion of chloride drawing water into the lumen causes?

secretory diarrhea

14

antidiarrheal that slow transit time leading to increased fluid absorption:

loperamide

15

Average transit time of the esophagus:

10 sec

16

Average transit time of the stomach:

4-5 hours

17

Average transit time of the small intestine:

2.5-3 hours

18

Average transit time of the colon:

30-40 hours

19

Biochemical characteristic of smooth muscle sphincters:

maintain tone without increase in intracellular Ca2+

20

Slow wave electrical activity of SM cells initiated by?

interstitial cells of Cajal

21

Increased AP generation of SM cells caused by increased?

amplitude

NOT frequency

22

Review SM contraction on slide...

37

23

NT released by enterochromaffin cells?

serotonin

24

role of serotonin in the gut?

afferent gut sensation

25

Excitatory NT's of the enteric nervous system:

Ach

neurokinin A

substance P

26

Inhibitory NT's of the enteric nervous system:q

vasoactive intestinal peptide

NO

27

Review slides...

45 and 46

28

NT's that generally decrease GI SM contractility:

norepinephrine

dopamine

neuropeptide Y

(Sympathetics....fight or flight)

29

NT's that generally increase GI SM contractility:

Ach

(parasympathetics....rest and digest)

30

Primary excitatory NT from sensory cells and motoneurons to muscle, epithelium, secretory cells and interneuronal junctions; increases intracellular Ca2+:

Acetylcholine