GI - 13

Question 1

The Enteric Nervous System

Answer 1

-coordinates peristalsis (contraction of GI tract)
-from esophagus to anus
-myenteric and submucosal plexus’ talks to glands and epithelium
-interstitial cells of cajal (in myenteric plexus) are pacemakers (decreases further down canal) of alimentary control

Question 2

ENS Crosstalk

Answer 2

Slide 5

Question 3

The Stomach

Answer 3

Mechanical and chemical digestion
-pH of. 1.5-3.5 (battery acid-lemon) –> protein denaturation/pathogen killing
-produces intrinsic factor (needed for B12 absoprtion - DNA synthesis)
-storage and slow chyme release
-esophagus to stomach = lower esophageal sphincter, leave stomach through pyloric sphincter

Question 4

Layer Features

Answer 4

Mucosa: rugae = intense folding and gastric pits and exocrine glands

Muscularis: oblique/circular/longitudinal for peristalsis and blending

Serosa = visceral peritoneum

Question 5

Stomach Venous Drainage

Answer 5

Slide 14
-drain into hepatic portal vein (gi vasculature goes to liver before back to heart)

Question 6

Stomach Innervation

Answer 6

CN 10 vagus - parasympathetic (stimulatory)
Splanchnic nerve - by way of celiac ganglia, sympathetic (inhibitory)

Question 7

Stomach Histology

Answer 7

LABEL SLIDE
gastric pit = mucus produced to produce epithelial cells from acidic environment
-parietal cells produce HCL and intrinsic factor
-chief cells produce pepsinogen and gastric lipase
-enteroendocrine cells secrete gastrin, increase parietal cell and chief cells, LES, motility, decrease pyloric sphincter

Question 8

BICARB equation in parietal cells

Answer 8

Slide
-innervated by paraympatheic (acetylcholine), mast cells (histamine) and gastrin (meals)

Question 9

Three Phases of Digestion

Answer 9

1. cephalic - vagus nerve stimulates gastric secretion before swallowing (also thinking/preparing about food)
2. Gastric - food stretches stomach, pH increase leading to myentiric reflex, gastric secretions and enzymes
3. intestinal phase - duodenum distention, chyme (fat and glucose) in durodenum, feedback to stomach

-CCK (fat/protein) and secretion say stop (secretions and muscle)
-enterogastric reflex = duodenum, spinal cord, brainstem, stomach, slow enteing into intestines

Question 10

Digestion Promotes/Inhibits

Answer 10

promotes:
-parasympathetic CN10. gatsrin, carbs and water

inhibits:
-sympathetic (splanchnic), enterogastric reflex, CCK and secretin, protein = moderate, fat = slow

Question 11

The Peritoneum

Answer 11

-membrane lining abdominopelvic cavity and organs
-protection of underlying organs via adiposity
-reduce friction around organs that move
-structure: peritoneal ligaments connect structures
-blood, lymph, nerve supply run through
-immunity - barrier to pathogens, recognizes invasive particles, drains waste

Question 12

Parietal vs Visceral

Answer 12

parietal: peritoneum lines body cavity walls

visceral: peritoneum covers organs (serosa)

Question 13

Five Peritoneal Folds

Answer 13

-Lesser Omentum
-Mesocolon
-Mesentery
-Falciform Ligament
-Greater Omentum