GI system

Question 1

General Gut Layers

Answer 1

Mucosa - epithelium, lamina propria, muscularis mucosae
Submucosa - Submucosal glands, blood vessels, submucosal nerve plexus
Muscularis - Inner circular layer, Myenteric nerve plexus, outer longitudinal layer
Serosa or Adventitia

Question 2

Mucosa

Answer 2

Epithelium
Lamina propria
Muscularis mucosa - smooth muscle that expels gland contents, not involved in movement of bulk

Question 3

Submucosa

Answer 3

Dense irregular CT
Large blood vessels
Meissner’s Submucosal Enteric Nerve Plexus - regulates mucosal epithelium and muscularis mucosa

Question 4

Muscularis externa

Answer 4

Smooth muscle - usually 2 layers. Skeletal muscle in pharynx, upper esophagus and external anal sphincter
Auerbach’s Enteric Plexus - nerves found between muscle layers, regulates motility

Question 5

Serosa or Adventitia

Answer 5

Serosa - mesothelium covering on more mobile regions (suspended in a cavity)
Adventitia - CT covering on more rigid regions

Question 6

Pharynx

Answer 6

Mucosa is stratified squamous non-keratinized
Lacks muscularis mucosae and submucosa
Irregularly arranged skeletal muscle
Coated in adventitia

Question 7

Esophagus

Answer 7

Upper 1/3 is voluntary, lower 2/3 involuntary, involved in peristalsis
Contains esophageal glands in submucosa
Coated in adventitia

Question 8

Stomach

Answer 8

Simple columnar epithelium
Adds acid to food to create chyme
Secretes lipase to digest triglycerides
Secretes pepsin to digest proteins

Question 9

Esophagitis

Answer 9

Inflammation of esophagus from acid regurgitated through upper esophageal sphincter

Question 10

GERD

Answer 10

Gastro-Esophageal Reflux Disease - chronic esophagitis

Question 11

Barrett Esophagus

Answer 11

Intestinal metaplasia of esophageal epithelium. Becomes simple columnar epithelium with lots of goblet cells. Looks like colon. Can develop into adenocarcinoma.

Question 12

Control of digestive activities

Answer 12

Neural control
Local factors
Hormone control

Question 13

Pits and glands

Answer 13

Inside of stomach
Pits are openings that vary in depth
Glands are located at the bottom of pits
Pit depth and gland location/type can help you determine where a tissue sample comes from.

Question 14

Cardia

Answer 14

Pits shorter than glands, glands almost all mucous

Question 15

Body and Fundus

Answer 15

Long glands with parietal and chief cells

Question 16

Pyloris

Answer 16

Glands mostly mucous, longer pits

Question 17

Mucous neck cell

Answer 17

Lines pits, secretes mucous and bicarbonate

Question 18

Parietal Cells

Answer 18

Secrete Gastric acid (HCl) and Gastric Intrinsic factor for vitamin B12 and Ca2+ absorption.
Unique “fried egg” appearance makes them easy to identify.

Question 19

Enterochromaffin-like Cells

Answer 19

Secrete histamine to stimulate acid production

Question 20

Chief cells

Answer 20

Secrete pepsinogen and gastric lipase

Question 21

D cells

Answer 21

Secrete somatostatin to inhibit acid production

Question 22

G cells

Answer 22

Secrete gastrin to stimulate acid production

Question 23

DNES

Answer 23

Diffuse neuroendocrine system

Question 24

APUD

Answer 24

Amine Precursor Uptake and Decarboxylation

Question 25

DNES cells secrete what?

Answer 25

Gastrin, glucagon, histamine, gherlin, somatostatin, serotonin

Question 26

Parietal Cell Acid Secretion

Answer 26

Carbonic anhydrase catalyses water and CO2 into H+ and HCO3-. HCO3- is transported out basally H+ and Cl- pumped out Apically H+ and Cl- join to become HCl

Question 27

Control of parietal cell acid secretion

Answer 27

Gastrin from G cells and histamine from enterochromaffin-like cells secrete HCl Cephalic control - 30%, smell taste, conditioning - Vagus nerve Gastric control - 60%, distension (vagus), Distension of antrum (local reflex), amino acids, small peptides (gastrin)

Question 28

Protective factors of GI epithelium

Answer 28

HCO3- and mucus, prostaglandins, mucosal blood flow, growth factors

Question 29

Damaging factors of GI epithelium

Answer 29

H+ and pepsin, H. pylori, NSAIDs, stress, smoking, alcohol

Question 30

Gastric movements

Answer 30

1. Propulsion 2. Grinding 3. Retropulsion

Question 31

Peristalsis

Answer 31

Move food along tract

Question 32

Segmentation

Answer 32

Alternate contraction mixes and moves food

Question 33

Peptic ulcer

Answer 33

Break in mucosa of stomach

Question 34

Gastric adenocarcinoma

Answer 34

Dysplasia of stomach mucosa