T.1 FUNCTIONS OF THE DIGESTIVE SYSTEM

Question 1

What are the three main purposes of organic molecules obtained from food?

Answer 1

to make ATP, build tissues, and serve as cofactors and coenzymes

Question 2

Why must most nutrients be broken down before use?

Answer 2

To convert them into smaller, usable components

Question 3

What is the function of the digestive system?

Answer 3

Processes food, extracts nutrients, eliminates residues

Question 4

What is the GI tract?

Answer 4

A muscular tube from mouth to anus open to the environment at both ends

Question 5

Why is the GI tract considered external to the body?

Answer 5

Because material is not inside the body until absorbed by epithelial cells

Question 6

What type of transport does the GI tract use?

Answer 6

One-way transport

Question 7

Why is one-way transport important in the GI tract?

Answer 7

Allows specialization of different regions for different functions

Question 8

What are the two subdivisions of the digestive system?

Answer 8

Gastrointestinal tract and accessory organs

Question 9

What organs make up the GI tract?

Answer 9

Mouth, pharynx, esophagus, stomach, small intestine, large intestine

Question 10

What are the accessory digestive organs?

Answer 10

Teeth, tongue, salivary glands, liver, gallbladder, pancreas

Question 11

What is motility in the digestive system?

Answer 11

Movement of food through the GI tract

Question 12

What are the stages of motility?

Answer 12

Ingestion, mastication, deglutination, peristalsis, segmentation

Question 13

What is digestion?

Answer 13

Breaking down of food polymers into monomers

Question 14

What is mechanical digestion?

Answer 14

Physical breakdown of food into smaller particles

Question 15

What are examples of mechanical digestion?

Answer 15

Cutting/grinding by teeth, churning by stomach and intestines

Question 16

What is chemical digestion?

Answer 16

Hydrolysis reactions that break macromolecules into monomers

Question 17

Where are digestive enzymes produced?

Answer 17

Salivary glands, stomach, pancreas, small intestine

Question 18

Which nutrients are absorbed without digestion?

Answer 18

Vitamins, free amino acids, minerals, cholesterol, water

Question 19

What is absorption?

Answer 19

Uptake of nutrients into epithelial cells and then into blood or lymph

Question 20

What is the function of storage and elimination?

Answer 20

Temporary storage and removal of undigested food

Question 21

What are the types of digestive secretion?

Answer 21

Exocrine (enzymes, acid, mucus), endocrine (hormones)

Question 22

How does the digestive tract act as an immune barrier?

Answer 22

Simple columnar epithelium with tight junctions prevents pathogen entry

Question 23

What are the four basic layers of the GI tract?

Answer 23

Mucosa, submucosa, muscularis externa, serosa

Question 24

What is the mucosa?

Answer 24

Inner secretory and absorptive layer lining the lumen

Question 25

What are the parts of the mucosa?

Answer 25

Inner epithelium, lamina propria, muscularis mucosae, MALT

Question 26

What is the function of muscularis mucosae?

Answer 26

Tenses mucosa to create folds for better digestion and absorption

Question 27

What is MALT?

Answer 27

Mucosa-associated lymphatic tissue with lymphocytes and nodules

Question 28

What is the submucosa?

Answer 28

Thicker connective tissue with blood vessels, lymphatics, nerve plexus, sometimes glands and MALT

Question 29

What is the muscularis externa?

Answer 29

Two layers of smooth muscle and a nerve plexus

Question 30

What is the function of the inner circular layer?

Answer 30

Forms valves and regulates material passage

Question 31

What is the function of the outer longitudinal layer?

Answer 31

Shortens tract and propels food and residue

Question 32

What is peristalsis?

Answer 32

Coordinated contraction of muscularis externa for food propulsion

Question 33

What is the serosa?

Answer 33

Outer protective layer made of connective tissue and mesothelium

Question 34

What is the serosa called in the abdominal cavity?

Answer 34

Visceral peritoneum

Question 35

What are mesenteries?

Answer 35

Connective tissue sheets suspending stomach/intestines from abdominal wall

Question 36

What are the functions of mesenteries?

Answer 36

Support organs, allow contractions, prevent twisting, provide vessel/nervous access, contain lymphatics

Question 37

What is the enteric nervous system?

Answer 37

Network in the GI tract regulating motility, secretion, and blood flow

Question 38

What are the two plexuses of the enteric nervous system?

Answer 38

Submucosal (Meissner's) and myenteric (Auerbach's)

Question 39

What does the submucosal plexus control?

Answer 39

Glandular secretion and movement of muscularis mucosae

Question 40

What does the myenteric plexus control?

Answer 40

Peristalsis and contractions of muscularis externa

Question 41

What do sensory neurons in the enteric system monitor?

Answer 41

Tension in the gut wall

Question 42

How is GI activity regulated?

Answer 42

Neural, hormonal, and paracrine mechanisms

Question 43

What is intrinsic neural control?

Answer 43

Enteric nervous system with Meissner’s and Auerbach’s plexuses

Question 44

What are paracrine secretions?

Answer 44

Chemical messengers diffusing through tissue to affect nearby cells (e.g., somatostatin)

Question 45

What is extrinsic neural control?

Answer 45

Autonomic nervous system influence (parasympathetic and sympathetic)

Question 46

What does the parasympathetic system do in digestion?

Answer 46

Stimulates motility and secretion

Question 47

What does the sympathetic system do in digestion?

Answer 47

Inhibits motility/secretion and stimulates sphincter contraction

Question 48

What are hormonal regulators in the GI tract?

Answer 48

Chemical messengers like gastrin and secretin acting at distant sites