GI Tract Physiology

Question 1

Layers (Tunics) of GI Wall

Answer 1

Mucosa:
Innermost layer (faces lumen)
Layer of epithelial cells specialized for absorption and secretion
Highly vascularized
Submucosa: Consists of collagen, elastin, glands, and blood vessels
Circular and Longitudinal Smooth Muscle: Provides motility for GI tract
Serosa: Faces the blood, outermost layer

Question 2

Stomach, Small and Large Intestine Functions

Answer 2

Stomach: digestion and break down of food to chyme (absorb-able particles.)
Small intestine: absorption of nutrients
Large intestine: absorption of water

Question 3

Three Phases of Digestion

Answer 3

Cephalic Phase : Cortex, amygdala and hypothalamus …. vagus nerve
Gastric Phase: hydrochloric acid and pepsin
Intestinal Phase: enterogastrone

Question 4

Gastrin

Answer 4

Secreted by G cells in stomach in response to eating
Secretion is inhibited by low pH in stomach
Promotes H+ secretion by gastric parietal cells
Stimulates growth of gastric mucosa
Causes Pepsinogen release from Chief cells
Relaxes Pyloric Sphincter

Question 5

the liver Receives major blood supply from

Answer 5

hepatic portal vein
Brings venous blood rich in nutrients from digestive tract
Has a very high blood glow with LOW vascular resistance

Question 6

Gilbert’s Disease

Answer 6

Impaired bilirubin conjugation (enzyme deficiency). Cause of clinical Jaundice

Question 7

Pancreatic Ducts

Answer 7

Main duct (Wirsung) runs the entire length of pancreas…Joins CBD at the ampulla of Vater

Lesser duct (Santorini) drains superior portion of head and empties separately into 2nd portion of duodenum

Question 8

Islets of Langerhans Four major cell types

Answer 8

Alpha (A) cells secrete glucagon
Beta (B) cells secrete insulin
Delta (D) cells secrete somatostatin
F cells secrete pancreatic polypeptide