Structure and Function of GI System

Question 1

Understand the term peritoneal cavity

Answer 1

the peritoneum is the largest serous membrane in the body; having a surface area approximately equal to that of the skin. two continuous layers - the visceral peritoneum and the parietal peritoneum (lines the wall of the abdominopelvic cavity)

mesentery: double layer of peritoneum that encloses a portion or all of one of the abdominal viscera & attaches it to the abdominal wall. contains blood vessels, nerves, and lymphatic vessels that supply the intestinal wall; holds organs in place & stores fat

omentum: a double-layered extension or fold of the peritoneum that passes from stomach or proximal part of duodenum to adjacent organs in the abdominal cavity or wall

Question 2

Understand three phases of swallowing

Answer 2

oral phase: bolus is collected at back of the mouth; tongue lifts food upward until it touches the posterior wall of pharynx

pharyngeal phase: respiration inhibited; bolus is moved backward into the esophagus by constrictive movements of the pharynx

esophageal phase: as food enters the esophagus and stretches its walls, local and central nervous system reflexes that initiate peristalsis are triggered

Question 3

Define pyloric stenosis

Answer 3

thickening or swelling of pylorus - causes severe & forceful vomiting in first few months of life

the pyloric sphincter prevents backflow of gastric contents and allows them to flow into the duodenum at a rate commensurate w/ ability of the duodenum to accept them.

Question 4

Know the major gastrointestinal hormones and their actions

Answer 4

Cholecystokinin (CCK): stimulates contraction of the gall bladder, stimulates secretion of pancreatic enzymes, slows gastric emptying.

Secretin: stimulates secretion by the pancreas and liver, inhibits gastric acid secretion.

Gastrin: stimulates secretion of gastric acid and pepsinogen.

Question 5

Know the importance of the gastric mucosal barrier

Answer 5

resistance to the highly acidic secretion it produces
also protects the stomach from pepsin

Question 6

Differentiate digestion from absorption

Answer 6

digestion: process of dismantling foods into their constituent parts

absorption: moving nutrients and other materials from the external environment of the GI tract into the internal environment

Question 7

Understand the role of small intestine brush border enzymes in carbohydrate and protein absorption

Answer 7

aid in the digestion of carbohydrates and proteins

Question 8

Know the role of the colon and Vitamin K

Answer 8

colonic microorganisms play a role in vitamin synthesis and in absorption of calcium, magnesium, and iron.
colonic flora synthesizes vitamin K.