GI tract

Question 1

What is the pylorus?

Answer 1

regulates passage of chyme

Question 2

What is chyme?

Answer 2

partially digested food and gastric juices formed in stomach

Question 3

What is gastric emptying?

Answer 3

stomach moves chyme into small intestine via pyloric sphincter

Question 4

How do fats affect gastric emptying?

Answer 4

they slow down gastric emptying due to releasing the hormone CKK

Question 5

How do carbohydrates affect gastric emptying?

Answer 5

speed up emptying

Question 6

What role does the vagus nerve play in gastric emptying?

Answer 6

regulates the contractions of the stomach and pyloric sphincter, influencing the rate of gastric emptying through parasympathetic control

Question 7

How does the hormone gastrin influence gastric emptying?

Answer 7

increases gastric motility and promotes the emptying of the stomach by stimulating muscle contractions in the stomach.

Question 8

How do hypertonic and acidic chyme affect gastric emptying?

Answer 8

slows down gastric emptying

Question 9

What does hydrochloric acid (HCl) do in the stomach?

Answer 9

HCl, secreted by parietal cells, lowers stomach pH to activate pepsinogen into pepsin and helps kill bacteria.

Question 10

What is the role of pepsinogen in digestion?

Answer 10

is secreted by chief cells
HCL converts pepsinogen to pepsin to break down proteins

Question 11

What function does mucus serve in the stomach?

Answer 11

protects stomach lining for gastric juices and digestive enzymes

Question 12

What is the function of gastric lipase?

Answer 12

is secreted by cheif cells
breaks down lipids

Question 13

How does histamine influence stomach activity?

Answer 13

is secreted by enterochromaffin like cells
stimulates parental cells to secrete HCL

Question 14

What does the hormone gastrin do?

Answer 14

secreted by G cells
stimulates parietal cells to release HCL
enhancing gastric motility

Question 15

What is the role of bicarbonate in the stomach

Answer 15

neutralises acid in mucous layer

Question 16

Which cells produce HCl in the stomach?

Answer 16

parietal cells

Question 17

What enzyme is involved in HCl production inside parietal cells?

Answer 17

carbonic anahydrase converts C02 and water into carbonic acid which then dissociates into bicarbonate and hydrogen

Question 18

How are hydrogen ions (H+) secreted into the stomach lumen?

Answer 18

primary active transport via H/K ATPase pump (proton pump)

Question 19

What happens to bicarbonate (HCO3-) during HCl production?

Answer 19

exchanged for chloride at basolateral membrane

Question 20

Which hormone stimulates HCl production and what pathway does it follow to do so?

Answer 20

gastrin
binds to CCK2
receptors on parietal cells
with subsequent activation
of PLC
PLC increases Calcium activating proton pump

Question 21

explain the pathway histamine follows to increase HCL production

Answer 21

upon stimulation by acetylcholine histamine binds to H2 receptors on basolateral membrane increasing adenyl cyclase activity therefore increasing cAMP and proton pump activity

Question 22

explain the pathway of Achieving effect on HCL production?

Answer 22

ACh is released by
parasympathetic cholinergic
neurons binding to
muscarinic (M3) ACh
receptors on parietal cells
with subsequent activation
of PLC therefore increasing proton pump activity

Question 23

What inhibits HCl secretion in the stomach?

Answer 23

somatostatin secured by D cells inhibits HCL secretion by suppressing gastrin release and directly inhibiting parietal cells

Question 24

What is the role of proton pump inhibitors (PPIs) in controlling HCl production?

Answer 24

blocks H/K ATPase pump (proton pump)

Question 25

which other lipid inhibits HCL secretion? and the pathway it follows

Answer 25

Prostaglandins bind to basolaterial membrane via EP3 receptors inhibiting adenyl cyclase activity

Question 26

What are the three phases of gastric secretion?

Answer 26

cephalic gastric intestinal

Question 27

What triggers the cephalic phase of gastric secretion?

Answer 27

thought , sight or smell of food stimulates gastric secretion via vagus nerve

Question 28

How is the cephalic phase of gastric secretion regulated?

Answer 28

CNS sends signals from brain activating vagus nerve to stimulate parietal, chief, and G-cells in the stomach

Question 29

What initiates the gastric phase of secretion?

Answer 29

when food enters the stomach stretching stomach walls activating stretch receptors

Question 30

How is the gastric phase of secretion regulated?

Answer 30

gastrin release from G cells stimulating HCL secretion

Question 31

What triggers the intestinal phase of gastric secretion?

Answer 31

when chyme enters duodenum

Question 32

How is the intestinal phase regulated?

Answer 32

secretin and CCK inhibit gastrin secretion and motility

Question 33

What is the main purpose of the intestinal phase?

Answer 33

controls rate of emptying

Question 34

How does acetylcholine enhance the activity of the H+/K+ ATPase?

Answer 34

is released from vagus nerve and binds M3 receptors on parietal cells increasing intracell Ca increasing proton pump activity

Question 35

Which second messenger system is activated by acetylcholine and gastrin to enhance H+/K+ ATPase activity?

Answer 35

increase intracellular Ca that activated H/K ATPase activity

Question 36

Which second messenger system is activated by histamine to enhance H+/K+ ATPase activity

Answer 36

activates cAMP

Question 37

What hormone is primarily responsible for stimulating the secretion of pancreatic enzymes and bile?

Answer 37

CCK

Question 38

Which hormone promotes the secretion of gastric acid in the stomach and is released when food enters the small intestine?

Answer 38

gastrin

Question 39

What hormone is released in response to low pH in the small intestine and stimulates the secretion of bicarbonate from the pancreas?

Answer 39

secretin

Question 40

How do hormones like CCK and secretin affect the motility of the small intestine?

Answer 40

slow down motility

Question 41

What effect does CCK have on gallbladder function?

Answer 41

stimulates contraction of gallbladder to eject bile into duodenum

Question 42

what type of cells of duo and jej secrete GIP ? what does it stimulate and inhibit

Answer 42

K cells stimulates released of insulin from pancreatic B cells inhibits gastric emptying

Question 43

what type of cells secretes GLP-1(small intestine) GLP-1 stimulates = GLP-1 inhibits= GLP-1 decreases=

Answer 43

L cells insulin secretion glucagon secretion from pancreatic a cells gastric emptying and appetite

Question 44

what type of cells of duo and jej secrete motilin and when are they secreted

Answer 44

M cells during fasting

Question 45

Ghrelin is secreted from ___ cells and stimulates ____

Answer 45

Gr appetite

Question 46

How does the pancreas contribute to digestion via its exocrine function?

Answer 46

secretes digestive enzymes into small intestine

Question 47

Which hormones does the pancreas secrete to regulate blood sugar levels?

Answer 47

insulin and glucagon

Question 48

role of goblet cells

Answer 48

create mucus layer

Question 49

What are the two main functions of the pancreas in relation to the GI tract?

Answer 49

endocrine = hormonal exocrine= digestive enzymes