25.1 General Anatomy and Digestive Processes

Question 1

digestive system

Answer 1

the organ system that processes food, extracts nutrients from it, and eliminates the residue

Question 2

ingestion

Answer 2

the selective intake of food

Question 3

digestion

Answer 3

the mechanical and chemical breakdown of food into a form useable by the body

Question 4

absorption

Answer 4

the uptake of nutrient molecules into the epithelial cells of the digestive tract and then into the blood or lymph

Question 5

compaction

Answer 5

absorbing water and consolidating the indigestible residue into feces

Question 6

defecation

Answer 6

the elimination of feces

Question 7

mechanical digestion

Answer 7

the physical breakdown of food into smaller particles

Question 8

chemical digestion

Answer 8

a series of hydrolysis reactions that break dietary macromolecules into their monomers, carried out by digestive enzymes

Question 9

digestive tract (alimentary canal)

Answer 9

a muscular tube: mouth, pharynx, esophagus, stomach, small intestine, large intestine

Question 10

gastrointestinal tract

Answer 10

stomach and intestines

Question 11

accessory organs

Answer 11

teeth, tongue, salivary glands, liver, gallbladder, pancreas

Question 12

mucosa (mucous membrane)

Answer 12

inner lining of the digestive tract, consisting of an epithelium, the lamina propria, and the muscularis mucosae

Question 13

lamina propria

Answer 13

a thin layer of areolar tissue immediately deep to the epithelium of a mucous membrane

Question 14

muscularis mucosae

Answer 14

a thin layer of smooth muscle immediately deep to the lamina propria of a mucosa

Question 15

submucosa

Answer 15

a thicker layer of loose connective tissue containing blood vessels and lymphatics, a nerve plexus, and glands that secrete lubricating mucus into the lumen

Question 16

muscularis externa

Answer 16

the external muscular wall of certain viscera such as the esophagus and small intestine

Question 17

serosa

Answer 17

a thin epithelial membrane composed of a simple squamous epithelium overlying a thin layer of areolar tissue that covers the external surfaces of viscera and forms membranes

Question 18

adventitia

Answer 18

a fibrous connective tissue layer in the pharynx, esophagus, and rectum that blends into the adjacent connective tissue of other organs

Question 19

enteric nervous system

Answer 19

a nervous network that regulates digestive tract motility, secretion, and blood flow

Question 20

submucosal plexus

Answer 20

network of neurons in the submucosa; controls movements of the muscularis mucosae and glandular secretion of the mucosa

Question 21

myenteric plexus

Answer 21

network of neurons consisting of parasympathetic ganglia and nerve fibers between layers of the muscularis externa; controls peristalsis and other contractions of the muscularis externa

Question 22

mesenteries

Answer 22

connective tissue sheets from which the stomach and intestines are loosely attached to the abdominal wall

Question 23

parietal peritoneum

Answer 23

a serous membrane that lines the wall of the abdominal cavity

Question 24

posterior mesentery

Answer 24

a translucent two-layered membrane extending to the digestive tract

Question 25

anterior mesentery

Answer 25

a sheet of tissue that hangs freely in the abdominal cavity or attaches to the anterior abdominal wall or other organs

Question 26

lesser omentum

Answer 26

mesentery that extends from the liver to the right superior margin (lesser curvature) of the stomach

Question 27

greater omentum

Answer 27

large, fatty mesentery that hangs like an apron from the left inferior margin (greater curvature) of the stomach, loosely covering the large intestine; part of the body’s first line against toxins and infections

Question 28

mesocolon

Answer 28

mesentery that anchors the colon

Question 29

milky spots

Answer 29

clusters of lymphatic tissues in the omentum that collect antigens from the peritoneal fluid and initiate an immune response

Question 30

intraperitoneal

Answer 30

within the peritoneal cavity; enclosed by mesentery (serosa) on all sides (e.g. stomach, liver, intestines)

Question 31

retroperitoneal

Answer 31

outside of the peritoneal cavity; adjacent to the posterior abdominal wall and covered by peritoneum on the anterior side only (e.g. duodenum, pancreas, large intestine)

Question 32

short (myenteric) reflexes

Answer 32

stretching or chemical stimulation of the digestive tract acts through the myenteric plexus to stimulate contractions in nearby regions of the muscularis externa (e.g. peristaltic contractions of swallowing)

Question 33

long (vagovagal) reflexes

Answer 33

reflexes that act through autonomic nerve fibers that carry sensory signals from the digestive tract to the brainstem and motor commands back to the digestive tract

Question 34

paracrine secretions

Answer 34

secretions (of histamine and prostaglandins) that diffuse through tissue fluids and stimulate nearby target cells