6. Digestive System

Question 1

Role of Mouth

Answer 1

mastication (mechanical breakdown)

Question 2

Role of Pancreas

Answer 2

creates digestive enzymes

Question 3

Role of Small Intestine

Answer 3

absorbs nutrients (95% of absorption)

Question 4

Role of Duodenum

Answer 4

mixes the chime with pancreatic enzymes

Question 5

Role of Colon

Answer 5

reabsorbs minerals and water into the blood

Question 6

Role of Rectum

Answer 6

gets rid of waste

Question 7

What are villi and microvilli?

Answer 7

• Villi are made up of microvilli

- They line the small intestine and absorb nutrients

Question 8

What are the enzymes in saliva, and what do they break down?

Answer 8

• Amylase and Lipase

- they break down food into smaller molecules to make them more easily absorbed

Question 9

What are the major cell types in the stomach, and what do they do? (4)

Answer 9

• Mucus Neck Cells: produce mucus that prevents the stomach from digesting itself
• Pariental Cells: produce HCl to adjust pH of the stomach
• Chief Cells - produce Pepsin which degrades food proteins
• Enteroendocrine Cells: initiate digestive actions

Question 10

What is Peristalisis? What causes? What is it’s function

Answer 10

• it’s a muscle contraction which causes a wave down a muscular tube
• it propels food and chyme through the digestive tract
• it’s caused by a wave contraction followed by a wave relaxation

Question 11

How does digestion occur in the stomach, and what is digested?

Answer 11

• Peristalsis occurs allowing the food to mix with pepsin and HCl
• PROTEINS ARE DIGESTED and chyme is created

Question 12

What are the 3 parts of the small intestine? Describe digestion/absorption of each

Answer 12

• Duodenum: mixes chyme with pancreatic enzymes
• Jejunum: absorbs nutrients that were broken down by the pancreatic enzymes in the duodenum
• Ileum - absorbs anything not absorbed by the jejunum

Question 13

What enzymes are produced in the Pancreas, and how are they activated?

Answer 13

• the pancreas produces chymotrypsinogen, bicarbonate, lipase/amylase, and trypsinogen
• they’re activated by proteolytic cleavage

Question 14

What is the function of bile salts, and where do they come from?

Answer 14

• they act as emulsifiers to lower cholesterol by emulsifying lipids
• they come from the liver

Question 15

What’s the difference between the endocrine and exocrine (digestive) parts of the pancreas?

Answer 15

• Endocrine secretes hormones into the internal environment; doesn’t have ducts
• Exocrine secretes sweat, oils, and wax into the external environment; has ducts

Question 16

What are the major cell types in the pancreas, and what do they do?

Answer 16

Centroacinar Cells (exocrine) - secrete bicarbonate

Acinar Cells - secrete digestive enzymes

Question 17

What are the major parts of the colon, and what happens in each part?

Answer 17

• Ascending colon (reabsorbs water and electrolytes)
• Transverse colon (more reabsorbtion of water and electrolytes)
• Descending colon (storage depot for feces)
• Sigmoid colon (moves stool into the rectum)

Question 18

What are the major hormones involved in digestion? (5)

Answer 18

Gastrin; Secretin; Cholecystokinin; GIP; Motilin

Question 19

Gastrin

Answer 19

• hormone from the stomach

- stimulates HCl secretion

Question 20

Secretin

Answer 20

• hormone from the duodenum

- signals secretion of sodium bicarbonate which stimulates bile secretion

Question 21

Cholecystokinin (CCK)

Answer 21

• hormone from the duodenum

- stimulates the release of bile and pancreatic enzymes

Question 22

Gastric Inhibitory Peptide (GIP)

Answer 22

• hormone from the duodenum
• induces insulin secretion
• slows rate of stomach emptying by inhibiting mixing and churning

Question 23

Motilin

Answer 23

• hormone from the duodenum

- stimulates production of pepsin

Question 24

How do insulin and glucagon differ in function?

Answer 24

• insulin: responds to high blood sugar

- glucagon: responds to low blood sugar