Lesson 15: The Digestive System

Question 1

What are the main functions of the digestive system?

Answer 1

Functions include digestion, absorption, motility, and secretion.

Moving nutrients, water, electrolytes, and removal of wastes

Question 2

What does GALT stand for and what is its function?

Answer 2

Gut associated lymphoid tissues; helps with immune functions

GALT plays a crucial role in the immune response within the digestive system.

Question 3

Outline the pathway food takes through the digestive system.

Answer 3

Mouth → esophagus → stomach → small intestine → large intestine → anus

Question 4

What are the 4 tissues of the digestive tract?

Answer 4

• Mucosa
• Submucosa
• Muscularis Externa
• Serosa

Question 5

What is the composition of the mucosa?

Answer 5

Epithelial cells lining the digestive tract, lamina propria, and muscularis mucosa

Question 6

What is contained in the submucosa?

Answer 6

Connective tissue, blood and lymph vessels, and the submucosal plexus (Meissner’s plexus)

Question 7

What is the muscularis externa made up of?

Answer 7

Outer wall of the digestive tract containing smooth muscle and the myenteric plexus (Auerbach’s plexus)

Question 8

What does the serosa do?

Answer 8

External/outtermost covering of the digestive tract

Question 9

What are carbohydrates broken down into?

Answer 9

Monosaccharides such as glucose, fructose, and galactose

Question 10

Where does carbohydrate digestion begin and what enzyme is involved?

Answer 10

Begins in the mouth with salivary amylase

Question 11

Where does protein digestion start and what are the breakdown products?

Answer 11

Starts in the stomach; broken down into amino acids, dipeptides, and tripeptides

Question 12

What enzyme initiates protein digestion in the stomach?

Answer 12

Pepsin, activated from pepsinogen by hydrochloric acid

Question 13

What are triglycerides broken down into?

Answer 13

Monoglycerides and free fatty acids

Question 14

Where does fat digestion begin? and which enzyme is involved?

Answer 14

In the mouth with lipase

Question 15

What are nucleic acids broken down into? where does this occur?

Answer 15

Nitrogenous bases and monosaccharides in the small intestine

Question 16

Define peristalsis.

Answer 16

The alternate waves of muscular contractions that move substances through the GI tract

Question 17

What is the role of the mouth in digestion?

Think 3 main roles

Answer 17

• Chemical digestion of carbohydrates
• Mechanical digestion through chewing (mastication)
• Secretion of salivary amylase and lipase

Question 18

Is the mouth involved in nutrient absorption?

Answer 18

No, it is not involved in absorption

Question 19

What is the primary function of the esophagus?

Answer 19

Motility; moving food from the mouth to the stomach

Question 20

What substances can the stomach absorb?

think hydrophilic stuff including recreational drinks.

Answer 20

Lipid-soluble substances such as aspirin and alcohol

Question 21

What is the function of parietal cells in the stomach?

think: secrete important acid

Answer 21

Secrete hydrochloric acid (HCL)

Question 22

What do chief cells in the stomach secrete?

hint: related to protein digestion

Answer 22

Pepsinogen, which becomes pepsin

Question 23

What do mucous cells secrete in the stomach?

Answer 23

• Mucus
• Bicarbonate

Question 24

What are the three regions of the small intestine?

Answer 24

• Duodenum
• Jejunum
• Ileum

Question 25

Where does most digestion and absorption occur?

Answer 25

In the small intestine

Question 26

What secretions are present in the small intestine? ## Footnote Hint: 4 main ones

Answer 26

* Enzymes from pancreas * Intestinal epithelial cells * Bicarbonate from pancreas * Bile from liver/gallbladder

Question 27

What is the role of the large intestine?

Answer 27

Concentrate waste and absorb water, minerals, and vitamins

Question 28

What stimulates the cephalic phase of gastric secretion? ## Footnote think senses

Answer 28

The sight, thought, or smell of food

Question 29

What triggers the gastric phase of gastric secretion?

Answer 29

The movement of food into the stomach

Question 30

What stimulates the intestinal phase of gastric secretion?

Answer 30

The movement of chyme into the small intestine

Question 31

What is the purpose of segmentation in digestion?

Answer 31

To separate chyme and mix it for digestion and absorption

Question 32

What major secretions does the pancreas provide? ## Footnote Hint: four P's and Bi---

Answer 32

* Pancreatic amylase * Pancreatic lipase * Proteases * Peptidases * Bicarbonate

Question 33

Where is bile made and stored?

Answer 33

Made in the liver and stored in the gallbladder

Question 34

What is the function of bile? ## Footnote hint: involved in digestion of one of the macros

Answer 34

Facilitate fat digestion

Question 35

What are long reflexes in the digestive system?

Answer 35

Digestive reflexes integrated in the CNS, initiated by stimuli like sight or smell

Question 36

What are short reflexes in the digestive system?

Answer 36

Digestive reflexes integrated within the enteric nervous system responding to local stimuli

Question 37

What is the enteric nervous system? whats another name for it?

Answer 37

The 'little brain' of the gut regulating digestive functions independently or with CNS input