CH2: Digestive System Intro

Question 1

What are the major digestive organs?

Answer 1

Oral Cavity
Esophagus
Stomach
Small Intestine
Large intestine

Question 2

What are the accessory digestive organs?

Answer 2

Salivary Glands
Liver
Gallbladder
Pancreas

Question 3

What is the general role of the oral cavity?

Answer 3

Consists of the mouth and the pharynx
Provides the entryway to the digestive tract
In the mouth mechanical breakdown occurs, moistening and mixing foods with saliva
The pharynx propels food from the back of the oral cavity into the esophagus

Question 4

What is the general role of the esophagus?

Answer 4

Transports food from the pharynx to the stomach

Question 5

What is the general role of the stomach?

Answer 5

Muscular contractions mix food with acid and enzymes, causing the chemical and physical breakdown of food into chyme

Question 6

What is the general function of the small intestine?

Answer 6

Major site of enzymatic digestion and nutrient absorption

Question 7

What is the general function of the large intestine?

Answer 7

Receives and prepares undigested food to be eliminated from the body as feces

Question 8

What is the general function of the salivary glands?

Answer 8

Release a mixture of water, mucus and enzymes

Question 9

What is the general function of the liver?

Answer 9

Produces bile, an important secretion needed for lipid digestion

Question 10

What is the general function of gallbladder?

Answer 10

Stores and releases bile, needed for lipid digestion

Question 11

What is the primary building block of bile?

Answer 11

Cholesterol

Question 12

What is the general function of the pancreas?

Answer 12

Releases pancreatic juice that neutralizes chyme and contains enzymes needed for carbohydrate, protein and lipid digestion

Question 13

What are the four layers of the digestive system/lumen?

Answer 13

Mucosa
Submucosa
Muscularis externa
Serosa

Question 14

What is the lumen?

Answer 14

Hollow central spaces in the digestive tract (like the esophagus, stomach interior, small intestine)

Question 15

What is the mucosa?

Answer 15

The innermost membrane layer
Produces and releases secretions needed for digestion
Lymphoid tissue protects the body
It is made of mucosal membrane, lamina propria, and muscularis mucosa

Question 16

What is the submucosa?

Answer 16

Made of connective tissue
Contains blood and lymphatic vessels, lymphoid tissue, nerves and submucosal plexus

Question 17

What is the muscularis externa?

Answer 17

Two layers of smooth muscle
- longitudinal muscle and circular muscle
- each of these muscle fibers run in different directions which influence muscular movements of the GI tract
Responsible for GI motility

Question 18

What is serosa?

Answer 18

Connective tissues
Outer cover that protects the GI tract
Flat mesothelial cells
Produces small amounts of lubricating fluid

Question 19

What is the enteric nervous system?

Answer 19

The digestive systems local nervous system
It includes about 100 million neurons neurons and their processes embedded in the layers of the GI tract beginning in the esophagus and extending in the anus
It is interconnected with the central nervous system
Influenced by the autonomic extensions of the CNS

Question 20

What are the two plexuses of the enteric nervous system?

Answer 20

Submucosa plexus (Meissner plexus)
Myenteric plexus (Auerbach plexus)

Question 21

What is the function of the submucosa plexus (Meissner plexus)

Answer 21

Typically controls the release of GI secretions and affects local blood flow regulation

Question 22

What is the function of the Myenteric plexus (Auerbach plexus)

Answer 22

This lies between the circular and longitudinal smooth muscles of the digestive tract
Generally controls motility, and when this plexus is stimulated, GI activity generally increases
Controls rate and intensity of contractions

Question 23

What are the three phases of digestion?

Answer 23

Cephalic
Gastric
Intestinal

Question 24

What occurs in the cephalic phase of digestion?

Answer 24

Sight, smell, taste, chewing and emotional state
Eating and tasting the food
Parasympathetic nerves (autonomic rest and digest) to ENS

Question 25

What occurs in the gastric phase of digestion?

Answer 25

Occurs when ingested food reaches the stomach Distention of the stomach(enlarging) occurs Acidity, amino acids and peptides Short and long neural reflexes Hormone: Gastrin

Question 26

What occurs in the intestinal phase of digestion?

Answer 26

The phase of gastric secretions that occur after food has left the stomach and has entered the duodenum Reduction in chyme volume in the stomach and reduction of the pH of gastric juice Short and long neural reflexes Hormone: Secretin, CCK, GIP