GI Overview

Question 1

What happens when you first smell food?

Answer 1

Salivary glands release:

• Serous/Mucous fluid -> HCO3
• Amylase
• Lipase

Churning of stomach

Activation of pancreas and Gall bladder by extrinsic nervous system

Question 2

What is the pathology of Sjogren’s syndrome?

Answer 2

• Autoimmune destruction of tissues —> Accumulation of ECM In Salivary glands
• Low levels of HCO3- —> Acidic contents —> Tissue injury/pain
• Dry mouth and dry eyes

Question 3

What happens to food in the stomach?

Answer 3

• Food storage
• Mixing of food
• Release of Acid/Lowering of pH
• Cells release Pepsinogen —> Pepsin; an enzyme which cleaves proteins

Question 4

Describe how Cystic fibrosis affects pancreas function?

Answer 4

• Pancreas stimulates lipase

- CF pancreas is damaged —> No production of lipase —> Fat malabsorption

Question 5

Differentiate functions of liver and gallbladder.

Answer 5

Liver:

• Make bile
• Recieves nutrients
• Makes blood proteins
• Detoxifier

Gallbladder: Stores and concentrates bile

Question 6

What occurs in the post pyramidal period?

Answer 6

Blood is diverted from skeletal muscles to intestines increasing blood blow up to 5X

Question 7

What are the Neurocrines of the GI system?

Answer 7

VIP, GRP, Enkephalins

Question 8

What is VIP and it’s function?

Answer 8

Vasoactive intestinal polypeptide:

• Homologue to secretin
• Produces relaxation of GI smooth muscle including lower esophageal sphincter
• Stimulates pancreatic HCO3- secretion and inhibits gastric H+ secretion

***VIPomz —> Watery diarrhea, Hypokalemia, and achlorhydria

Question 9

What are the paradise mechanisms of the GI system?

Answer 9

Gastrin + Vagus Nerve —>Histamine —> INC H+ by parietal cells

INC Luminal H+ and D cells of GI system —> Somatostatin —> DEC Gastrin and histamine release ad therefore DEC H+ secretion

Question 10

What is GIP and what are it’s triggers and actions? What cells secrete it?

Answer 10

Glucose-dependent insulinotropic peptide:

• Secreted by K Cells of duodenum
• Stimulated by Fats, FAs, Proteins, Carbohydrates, glucose
• Decreases H+ secretion, motility, and emptying
• Increases Insulin secretion
• Stimulates Insulin secretion

***At large does, inhibits gastric secretion and motility

Question 11

Describe Gastrin:

• Release
• Action
• Inhibition

Answer 11

• Released vey parietal cells
• INC H+ and stimulates growth of gastric mucosa
• Stimulated by Stomach distention, vagus nerve via GRP, and Phe/Try
• Inhibited by H+ in lumen of stomach, somatostatin
• inhibited by Zollinger-Ellison syndrome

*Gastrin is inactive in kidney and SI

Question 12

Describe Zollinger Ellison Syndrome

Answer 12

• Gastrinoma
• Uncontrolled increase in Gastrin Secretion which upregulates gastric secretions
• Parietal Cell Hyperplasia in body
• Gastric ulcers in unusual locations such as esophagus and Jejunum

Question 13

Describe Secretin:

• Release
• Function
• Inhibition

Answer 13

• Homologue to glucagon
• Stimulates HCO3- Secretion and exocrine pancreas
• Increase bile production
• Inhibits H+ release by parietal cells
• Stimulated by S Cells of Duodenum from too much H+ or Fatty Acids

Question 14

Describe CCK:

• Secretion
• Functions
• Inhibition
• stimulation

Answer 14

• Homologue to Gastrin
• I Cell of Duodenum
• Contracts gallbladder, relaxes sphincter of Oddi, stimulates pancreas, Stimulates secretin
• Inhibits Gastric emptying via contracting pyloric sphincter
• Stimulated by small peptides and amino acids (NOT triglycerides)

Question 15

What is the only hormone which responds to Fat, protein, and carbohydrates?

Answer 15

GIP

Question 16

Describe the organization of the Enteric Nervous system

Answer 16

Myeneteric Plexus (Auerbach) —> Gut motility

Submmucosal plexus (Meissner) —> Intestinal absorption and secretion

Question 17

What are the different neurotransmitters of the ENS?

Answer 17

Ach - Motility and secretion

ATP/NO - Inhibitory NTs

VIP - Stimulate intestinal fluids and secretion and Vasodilation

Substance P - Contraction

GRP - Gastric secretion

Question 18

Describe Ghrelin:

• Secretion
• Stimulation
• Function
• Inhibition

Answer 18

• Secreted by Gastric cells
• Stimulates orexigenic neurons; nhjibits anorexigenic neuron and increasing appetite
• Central control of food uptake