Lecture 19 -- review questions

Question 1

what are the 4 regions of the stomach?

Answer 1

cardia
fundus
body
pyloric part

Question 2

what areas form the pyloric part of the stomach?

Answer 2

pylorus
pyloric canal
pyloric sphincter
antrum

Question 3

how many layers of muscularis externa does the stomach have?

Answer 3

3 layers

Question 4

what is the purpose of stomach rugae?

Answer 4

wrinkles (mucosal folds) that allow gastric expansion

Question 5

where is the pyloric sphincter?

Answer 5

pyloric part of stomach

connects the stomach to the duodenum

Question 6

what is the primary function of the pyloric sphincter?

Answer 6

regulates passage of chyme into duodenum

Question 7

what 3 mechanisms protect the stomach from the harsh acidic and enzymatic environment?

Answer 7

1) mucous-bicarbonate barrier
2) epithelial tight junctions
3) damaged epithelial cell replacement (stem cells)

Question 8

what its he pH of the stomach?

Answer 8

1.5

Question 9

how often do epithelial cells regenerate (are renewed)?

Answer 9

3-6 days

Question 10

the stomach’s epithelial cells have a mucous coat rich in which ion?

where is that ion coming from? (ie which cells produce it?)

Answer 10

bicarbonate ion

mucous neck cells

Question 11

why can this ion help protect from acid that flow close to the stomach’s epithelial cells?

Answer 11

combines with H+ from acid to form H2O and CO2

Question 12

does the stomach have any secretion coming from accessory glands?

Answer 12

no – stomach doesn’t have any secretions coming from accessory glands –> only from stomach glands

Question 13

why are the stomach’s epithelial cells very close together, minimizing the space b/n them?

how is this achieved? (think about how the cells are joined)

Answer 13

packed close together to make sure no gastric juice seeps b/n them

Question 14

what is the name of the gastric fluid secreted by the glands in the stomach: rich in water, acid, and pepsin called?

Answer 14

gastric juice

Question 15

in the gastric glands, what do mucous cells secret?

Answer 15

mucus and bicarbonate

Question 16

in the gastric glands, what do parietal cells secrete?

Answer 16

HCl (gastric acid)

intrinsic factor

Question 17

in the gastric glands, what do chief cells secrete?

Answer 17

pepsin(ogen)

gastric lipase

Question 18

in the gastric glands, what do G cells secrete?

Answer 18

gastrin

Question 19

in the gastric glands, what do enteroendocrine cells secrete?

Answer 19

hormones – ghrelin, somatostatin, gastrin, serotonin

Question 20

in the gastric glands, what do enterochromaffin cells secrete?

Answer 20

histamine

Question 21

what is the intrinsic factor? where is it produced?

Answer 21

glycoprotein that aids in vitamin B12 absorption by small intestine

produced by parietal cells in stomach

Question 22

what converts pepsinogen to active pepsin?

Answer 22

activated by HCl

Question 23

the digestion of proteins begins in the stomach; which enzyme secreted in the gastric glands digests proteins?

Answer 23

pepsin

Question 24

what is gastrin? what is its function in the stomach?

Answer 24

a hormone secreted by G cells

promotes parietal cells to secrete HCl

Question 25

what is the name of the pump that plays an essential role in gastric acid production? which 2 ions does it exchange?

Answer 25

H+/K+ ATPase pumps K+ from stomach lumen into cytosol of parietal cell pumps H+ from parietal cell to stomach lumen

Question 26

what is the name of the acid of the stomach?

Answer 26

hydrochloric acid

Question 27

where is the H+ used by the proton pump coming from?

Answer 27

carbonic acid (H2CO3) breakdown from inside the parietal cell

Question 28

what cells produce acid in the stomach?

Answer 28

parietal cells

Question 29

why do parietal cells transport the H+ and Cl- into the gastric lumen separately?

Answer 29

can't create HCl directly in cytoplasm --> would destroy the cell

Question 30

what stimulates stomach acid production? (indicate the 3 factors: neural, paracrine, and hormonal)

Answer 30

NAM PHH HGC - new Amsterdam must play honey hockey house goose chase neural: - parasympathetic nerve fibers of both short and long reflex pathways - ACh, M3 paracrine: - histamine, H2 hormonal: - gastrin, CCK2

Question 31

which 2 factors stimulate the release of gastrin? by which cells?

Answer 31

peptides and increased pH hormone-G cells (in duodenum and pyloric antrum)

Question 32

what is called chyme?

Answer 32

acidic, soupy/pasty mixture of semi digested food

Question 33

what are the names of the 3 phases of gastric acid secretion?

Answer 33

cephalic gastric intestinal

Question 34

what stimulates gastric acid secretion during the cephalic phase?

Answer 34

thought, sight, smell, taste of food

Question 35

which autonomic NS subdivision mediates the cephalic phase effects? which enteric plexus is involved in this response?

Answer 35

parasympathetic NS vagus nerve submucosal/meissner's plexus

Question 36

what stimulates gastric acid secretion during the gastric phase?

Answer 36

food enters stomach and stretches stomach (distension) --> detected stretch receptors gastrin is secreted

Question 37

in which 2 phases does gastrin play a role in gastric acid secretion?

Answer 37

gastric intestinal

Question 38

what stimulates gastric acid secretion during the intestinal phase?

Answer 38

chyme arrives at duodenum --> duodenum is distended (stretched) --> detected by stretch receptors gastrin is secreted

Question 39

in which gastric acid secretion phase does the enterogastric reflex occur?

Answer 39

intestine

Question 40

what is the name of the nervous reflex whereby stretching of the wall of the duodenum results in inhibition of gastric motility (including peristalsis) and reduced stomach emptying rate?

Answer 40

enterogastric reflex

Question 41

which hormones are released during the intestinal phase by the duodenum and act on the stomach to inhibit gastric secretion and motility?

Answer 41

secretin GIP (gastric inhibitory peptide) CCK (cholecystokinin)

Question 42

which factor stimulates the secretion of secretin by intestinal cells?

Answer 42

low pH (chyme is very acidic --> duodenum doesn't want to be that acidic)

Question 43

what does GIP stand for?

Answer 43

gastric inhibitory peptide

Question 44

what does CCK stand for?

Answer 44

cholecystokinin

Question 45

where are CCK and secretin produced?

Answer 45

small intestine

Question 46

what are the structural and functional units of the liver? what is their shape in cross-section?

Answer 46

liver lobules haxagonal shape

Question 47

what are hepatocytes? where are they found?

Answer 47

liver cells all throughout the liver

Question 48

where is the portal triad found in the cross-section of a liver lobule?

Answer 48

spread out surrounding the central vein in the middle

Question 49

what 3 structures make up a portal triad?

Answer 49

bile duct hepatic artery portal vein

Question 50

where can you find Cholangiocytes?

Answer 50

epithelial cells in the bile duct

Question 51

where can you find Kupffer cells? what are they?

Answer 51

line the endothelial sinusoids of the liver macrophages

Question 52

where can you find Stellate cells? name 2 functions of these cells

Answer 52

located b/n endothelial sinusoids and hepatocytes of liver major storage site for Vitamin A activate fibrogenesis (scar creation) upon liver damage

Question 53

which cells produce bile?

Answer 53

hepatocytes

Question 54

after the production of bile, where is this bile secreted?

Answer 54

bile canaliculi (channels)

Question 55

which "tube" connects the bile canaliculi w/ the bile (or biliary duct)?

Answer 55

canal of Hearing or Ductule

Question 56

which hormone stimulates the cholangiocytes to secrete bicarbonate and water into the bile at the bile duct?

Answer 56

secretin --> stimulates cholangiocytes to stimulate bicarbonate and water into the bile at the bile duct

Question 57

which 2 ducts form the common bile duct?

Answer 57

common hepatic duct cystic duct

Question 58

what is the ampulla of Vater or (hepatopancreatic ampulla)?

Answer 58

spot where the pancreatic and bile ducts release their secretions into the intestines

Question 59

what sphincter controls the secretion of pancreatic juice and bile into the duodenum?

Answer 59

Sphincter of Oddi (hepatopancreatic sphincter) --> muscular valve

Question 60

what does CCK produce in the gallbladder: contraction or relaxation? does it help or oppose the stored bile's secretion into the cystic duct?

Answer 60

contracts gallbladder helps move bile from gallbladder into cystic duct to reach the small intestine

Question 61

what does CCK produce in the Sphincter of Oddi: contraction or relaxation? does it promote or prevent the secretion of bile and pancreatic juice into the duodenum?

Answer 61

relaxation promotes bile and pancreatic juice to enter the duodenum

Question 62

what is pancreatic juice?

Answer 62

bicarbonate-rich fluid containing enzymes that digests all categories of foods carried to the duodenum via the pancreatic duct

Question 63

in which organ of the alimentary canal is this pancreatic juice poured?

Answer 63

duodenum pancreatic duct --> ampulla of Vater (hepatopancreatic ampulla)

Question 64

which 2 types of cells form part of the exocrine pancreas?

Answer 64

acinar cells duct cells

Question 65

where are the acinar cells located (organ)?

Answer 65

acinar cells are found in acini (cluster units) of exocrine pancreas

Question 66

what do acinar cells secrete? which hormone stimulates this secretion?

Answer 66

enzyme-rich component of pancreatic juice CCK stimulates acinar cells to secrete enzyme-rich component of pancreatic juice

Question 67

which 2 ducts form the common hepatic duct?

Answer 67

left and right hepatic duct

Question 68

what is the name of the granules found in the acinar cells? what do they contain?

Answer 68

zymogen granules contain inactive enzymes (proenzymes or zymogens)

Question 69

what do pancreatic duct cells secrete? which hormone stimulates this secretion?

Answer 69

watery secretion (rich in bicarbonate ions) of pancreatic juice secretin stimulates pancreatic duct cells to secrete this watery secretin (rich in bicarbonate ions) of pancreatic juice

Question 70

what are the Islets of Langerhans, and what do they produce?

Answer 70

make up the endocrine portion of the pancreas produce insulin and glucagon

Question 71

what are zymogen forms of enzymes? trypsinogen --> ___ chymotrypsinogen --> ___ procarboxypeptidase --> ___

Answer 71

inactive digestive enzymes that get converted to active form after secretion trypsinogen --> trypsin chymotrypsinogen --> chymotrypsin procarboxypeptidase --> carboxypeptidase trypsin catalyzes production of more trypsin and activates the other pancreatic zymogen

Question 72

what are 3 zymogens secreted by the pancreas for protein digestion? what is the name of the corresponding active enzyme?

Answer 72

trypsinogen --> trypsin chymotrypsinogen --> chymotrypsin procarboxypeptidase --> carboxypeptidase trypsin catalyzes production of more trypsin and activates the other pancreatic zymogen