BSI 2 Lecture 65-66: Lower GI Tract

Question 1

Where does most digestion and absorption occur?

Answer 1

Small intestine

Question 2

What is responsible for digestion in the small intestine?

Answer 2

enzymes on the intestinal wall or brush border, pancreatic juice, and bile

Question 3

What do the crevices between the villi form?

Answer 3

crypts of lieberkuhn

Question 4

What do the crypts of lieberkuhn do?

Answer 4

secrete digestive juices

Question 5

What is contained in the submucosa of the small intestine?

Answer 5

Brunner’s glands

Question 6

What do Brunner’s glands do?

Answer 6

Secrete alkaline mucus with NaHCO3 that helps neutralize gastric acid in the chyme

Question 7

What cells are in the small intestine?

Answer 7

1. absorptive cells
2. goblet cells
3. S cells
4. CCK cells
5. K cells
6. L cells
7. Paneth cells

Question 8

What do absorptive cells contain?

Answer 8

Brush border enzymes

Question 9

What are the brush border enzymes?

Answer 9

1. maltase
2. sucrase
3. lactase
4. alpha-dextrinase
5. aminopeptidase
6. dipeptidase
7. nucleosidases
8. phosphatases
9. enterokinase

Question 10

What does maltase do?

Answer 10

digests maltose into glucose + glucose

Question 11

What does sucrase do?

Answer 11

digests sucrose into glucose+ fructose

Question 12

What does lactase do?

Answer 12

digests lactose into glucose + galactose

Question 13

What does alpha-dextrinase do?

Answer 13

breaks down dextrins into glucose

Question 14

What does aminopeptidase do?

Answer 14

digests proteins

Question 15

What does dipeptidase do?

Answer 15

Breaks down dipeptides into amino acids

Question 16

What do nucleosidases do?

Answer 16

digest nucleic acids

Question 17

What do enterokinases do?

Answer 17

activate trypsinogen into trypsin which digests proteins

Question 18

What do goblet cells do?

Answer 18

secrete mucous

Question 19

What do S cells secrete?

Answer 19

secretin

Question 20

What do CCK cells secrete?

Answer 20

CCK

Question 21

What do K cells secrete?

Answer 21

Glucose-dependent insulinotrophic peptide

Question 22

What do L cells secrete?

Answer 22

GLP-1

Question 23

What do paneth cells do?

Answer 23

secrete lysozyme and bactericidal enzyme

Question 24

What is the pancreas made of?

Answer 24

small clusters of glandular epithelial cells

Question 25

How much pancreatic juice is secreted per day?

Answer 25

1500 mL

Question 26

What does pancreatic juice consist of?

Answer 26

1. water 2. salts 3. sodium bicarbonate 4. digestive enzymes

Question 27

What digestive enzymes are included in pancreatic juice?

Answer 27

1. pancreatic amylase 2. pancreatic lipase 3. trypsin 4. chemotrypsin 5. carboxypeptidase 6. elastase 7. ribonuclease 8. deoxyribonuclease

Question 28

How do the protein digesting enzymes in the pancreas get activated?

Answer 28

Enterokinase cleaves trypsinogen into trypsin, in the duodenum, and trypsin activates everything else

Question 29

During which phases is pancreatic juice secreted?

Answer 29

the cephalic, gastric, and intestinal phases

Question 30

What solid organ can regenerate itself?

Answer 30

Liver

Question 31

Where is the gallbladder located?

Answer 31

In the posterior surface of the liver

Question 32

What does the liver do?

Answer 32

Produces and secretes bile

Question 33

What does the gallbladder do?

Answer 33

stores and concentrates bile

Question 34

What makes up the liver?

Answer 34

lobes made of lobules

Question 35

What does the liver have instead of capillaries?

Answer 35

sinusoids

Question 36

What are sinusoids?

Answer 36

endothelial-lined spaces that contain Kupffer cells

Question 37

Where does the liver receive oxygenated blood from?

Answer 37

Branch of the hepatic artery

Question 38

Where does the liver receive blood that is deoxygenated and needs filtering?

Answer 38

Branch of the hepatic portal vein

Question 39

What makes up bile?

Answer 39

water, bile salts/acids, cholesterol, lecithin, bile pigments, ions and other things

Question 40

What are the functions of bile?

Answer 40

1. breakdown of large lipid globules 2. formation of micelles which bind lipids to wall of GI tract for absorption 3. excretion of cholesterol, calcium, bilirubin, and drugs

Question 41

How does bile get stored in the gallbladder?

Answer 41

The sphincter of Oddi has to be closed so bile can enter the cystic duct

Question 42

What is the pathway of bile secretion?

Answer 42

Bile is secreted by hepatocytes, caniliculi, bile ductules, bile duct, right and left hepatic ducts, exits liver via common hepatic duct

Question 43

What is the large intestine composed of?

Answer 43

simple columnar epithelium, long tubular intestinal glands, and lymphatic nodules

Question 44

What cells make up the large intestine?

Answer 44

goblet cells and absorptive cells

Question 45

Does digestion macromolecules occur in the large intestine?

Answer 45

No

Question 46

What happens in the final stages of digestion?

Answer 46

1. ferment remaining carbohydrates 2. break down AA into smaller components 3. synthesize short chain fatty acids

Question 47

Where is 90% of water reabsorbed?

Answer 47

small intestine

Question 48

Where does mass paristalsis occur?

Answer 48

transverse colon

Question 49

What initiates the gastrocolic reflex?

Answer 49

Food in the stomach

Question 50

Steps of the defecation reflex

Answer 50

stretch receptors, sacral spinal cord, PNS, sigmoid colon, rectum, anus, contraction of longitudinal rectal muscles, increase pressure, opening of internal anal sphincter, defecation if external sphincter is relaxed