Chapter 9: The Digestive System

Question 1

Enteric nervous system

Answer 1

Collection of one hundred million neurons that governs the function of the GI system; present in the walls of the digestive tract and trigger peristalsis; can function independently of the CNS although it is heavily regulated by the autonomic nervous system

Question 2

Parasympathetic control of the ENS

Answer 2

Stimulation of digestive activities, increasing secretions from exocrine glans and promoting peristalsis

Question 3

Parts of the pharynx

Answer 3

Nasopharynx; oropharynx, and the laryngopharynx

Question 4

Anatomical divisions of the stomach

Answer 4

Fundus and body (contain mostly gastric glands) and the antrum and pylorus (contain mostly pyloric glands)

Question 5

Gastric glands

Answer 5

Respond to signals from the vagus nerve of the parasympathetic nervous system; activated by the brain in response to the sight, taste, and smell of food

Question 6

Cell types of gastric glands

Answer 6

Mucous cells - produce bicarbonate-rich mucus that protects the muscular wall from the harshly acidic (pH = 2) and proteolytic environment of the stomach
Chief cells - secrete pepsinogen
Parietal cells - secrete hydrochloric acid that cleaves pepsinogen into pepsin

Question 7

Pepsin

Answer 7

Cleaves peptide bonds near aromatic amino acids, resulting in shorter peptide fragments

Question 8

Intrinsic factor

Answer 8

Secreted by parietal cells; a glycoprotein involved in proper absorption of vitamin B12

Question 9

Pyloric glands

Answer 9

Contain G cells that secrete gastrin

Question 10

Gastrin

Answer 10

Induces the parietal cells in the stomach to secrete more HCl and signals the stomach to contract, mixing its contents

Question 11

Chyme

Answer 11

Acidic, semifluid mixture; combined mechanical and chemical digestive activities of the stomach result in a significant increase in the surface area of the now unrecognizable food particles

Question 12

How long is the small intestine?

Answer 12

7 meters

Question 13

Duodenum

Answer 13

Responsible for the majority of chemical digestion and has some minor involvement in absorption

Question 14

Jejunum and ileum

Answer 14

Majority of absorption

Question 15

Enteropeptidase

Answer 15

Involved in the activation of other digestive enzymes (trypsinogen and procarboxypeptidases A and B) from the accessory organs of digestion; secreted by the duodenum along with secretin and cholecystokinin

Question 16

Secretin

Answer 16

Peptide hormone that causes pancreatic enzymes to be released into the duodenum; regulates pH in the duodenum by reducing HCl secretion from parietal cells and increasing bicarbonate secretion from the pancreas; enterogastrone that slows motility through the digestive tract (increases the time for digestive enzymes to work on fats)

Question 17

Cholecystokinin

Answer 17

Secreted in response to the entry of chyme into the duodenum (especially amino acids and fats); stimulates the release of both bile and pancreatic juices and also acts in the brain where it promotes satiety

Question 18

Functions of the liver

Answer 18

Processing of nutrients (glycogenesis and glycogenolysis, storage and mobilization of fats, gluconeogenesis), production of urea, detoxification of chemicals, production of bile and synthesis of albumin and clotting factors

Question 19

Bilirubin

Answer 19

Byproduct of the breakdown of hemoglobin

Question 20

Gallbladder

Answer 20

Located just beneath the liver and both stores and concentrates bile; upon release of CCK, the gallbladder contracts and pushes bile out into the biliary tree; common site of cholesterol or bilirubin stone formation

Question 21

What are the three sections of the large intestine

Answer 21

Cecum (with the appendix and receives fluid exiting the small intestine through the ileocecal valve); colon (ascending, transvserse, descending, sigmoidal); rectum (storage site for feces_