Digestion 2

Question 1

Where do the short reflexes originate and how are they intergrated?

Answer 1

Originate in the Enteric nervous system and are integrated w/o CNS

Question 2

Where do the long reflexes originate and how are they intergrated?

Answer 2

Originate in the Enteric nervous system and are integrated w/ CNS

Question 3

Where do cephalic reflexes originate?

Answer 3

CNS

Question 4

Name 3 places secretions can be released

Answer 4

Released into the blood
Released into the lumen
Secretion to neighbouring cells

Question 5

What do serous acini secret?

Answer 5

amylase

lipase

Question 6

What do mucous acini secrete?

Answer 6

mucous

Question 7

What do ducts cells secrete?

Answer 7

Water and HCO3

Question 8

What is secreted alongside mucous and why?

Answer 8

Bicarbonate to buffer gastric acid to prevent damage to epithelium

Question 9

What stimulates secretion of HCl and intrinsic factors?

Answer 9

Acetylcholine
Gastrin
Histamine

Question 10

What cells secrete HCl and what is HCls function?

Answer 10

Parietal cells

HCl activates pepsin and kills bacteria

Question 11

What cells secret intrisic factors and what is IFs function?

Answer 11

Parietal cells

IF form complexes w/ Vitamin B-12 to permit absorption

Question 12

What cells secrete Histamine and what is Histamines function?

Answer 12

Enterochromaffin like cell

Stimulates gastric acid secretion

Question 13

What does Acetylcholine stimulate the release of in the stomach?

Answer 13

Hcl
Intrinsic Factor
Histamine
Pepsin
gastric lipase
gastrin

Question 14

What cells secrete Pepsin and what is Pepsins function?

Answer 14

Chief cells

Digests proteins

Question 15

What cells secrete gastric lipase and what is Gastric lipases function?

Answer 15

Chief cells

Digests fats

Question 16

What cells secrete Somatostatin and what is Somatostatins function?

Answer 16

D cells

Inhibits gastric secretion

Question 17

What cells secrete Gastrin and what is Gastrins function?

Answer 17

G cells

Stimulates gastric acid secretion

Question 18

What controls the long reflexes?

What makes up the ENS ‘little brain’

Answer 18

Autonomic control

Sensory receptors and neurons- inter-neurons- enteric neurons

Question 19

Describe bicarb secretion
Cells often have high con of what?
What enters and leaves the cell?

Answer 19

High con of carbonic anhydrase.
Cl- enter cells by AT and leave through CFTR channel, it reenters in exchange for HCO3-

Na+ and H2O leave the cell as well

Question 20

G cells/ Gastrin

What is the stimulate for release?
What is the primary target and effect?

Answer 20

Stimulus= peptides, aa, neural reflexes

target= ECL cells, parietal cells to stimulate gastric acid secretion and mucosal growth

Question 21

Cholecystokinin / CCK

What is the stimulate for release?
What is the primary target and effect?

Answer 21

Stimulus- FA, some aa
target- gallbladder, pancreas, stomach
Effect- stimulates HCO3- secretion
Inhibits gastric emptying and acid secretion

Question 22

Motilin
What is the stimulate for release?
What is the primary target and effect?

Answer 22

Stimulus- Fasting released every 1.5-2 hours

Target- gastric and intestinal smooth muscle.

Question 23

Gastric inhibitory Peptide / GIP
What is the stimulate for release?
What is the primary target and effect?

Answer 23

Stimulus- glucose, FA, aa in small intestine
Targte- Beta cells of pancreas
Effect- stimulate insulin release, in hibtis gastic emptying and acid secretion

Question 24

Glucagon-like peptide-1 / GLP-1
What is the stimulate for release?
What is the primary target and effect?

Answer 24

Stimulus- mixed meal in the lumen
Target- endocrine pancreas
Effect- insulin release
inhibits glucagon release and gastric function

Question 25

What 2 things promote satiety?

Answer 25

GLP-1 | CCK

Question 26

What is amylase broken down into?

Answer 26

Maltose

Question 27

Describe the enzyme and product for the breakdown of Maltose

Answer 27

Maltase breaks maltose into 2 glucose molecules

Question 28

Describe the enzyme and product for the breakdown of sucrose

Answer 28

Sucrase breaks sucrose into 1 glucose and one fructose

Question 29

Describe the enzyme and product for the breakdown of lactose

Answer 29

Lactase breaks lactose into one glucose and one galactose

Question 30

What do carbs require to cross from the lumen into the blood?

Answer 30

Transporters Glucose/galactose enter the intestinal mucosa w/ Na+ via SGLT and exits on GLUT2 Fructose enters on GLUT5 and exits on GLUT2

Question 31

Name the 2 types of peptidases

Answer 31

Endopeptidases | Exopeptidases

Question 32

Name examples of endopeptidases

Answer 32

Pepsin | Trypsin

Question 33

Which bonds to endopeptidases break?

Answer 33

Internal peptide bonds

Question 34

What bonds do exopeptidases break?

Answer 34

Terminal peptide bonds to release amino acids

Question 35

Match the peptide size to the mode of protein absorption. Amino acid Di-tripeptide Small peptides H+ cotransport Endo/exocytosis Na+ cotransport

Answer 35

Amino acid= Na+ co trasnport Di-tripeptide= H+ co transport Small peptides - endo/exocytosis

Question 36

Describe how lipids are digested

Answer 36

Fat droplets are emulsified by bile salts to produce micelles Micelles split into glyceol and FA to cross the lumen wall. Cholestrol+TG+protein= chylomicron which moves to golgi then leaves via exocytosis

Question 37

Describe iron absorption

Answer 37

Fe2+ comes from food and breakdown of heme ( already in the membrane) Fe2+ enters via H+ co transport and enters via ferroportin

Question 38

Describe calcium absorption

Answer 38

paracellualr is not regulated | Ca2+ moves into membrane vai Ca channel then exits w/ ATP of as 3Na+ goes in

Question 39

Name the 3 ways NA enters the cell

Answer 39

Na channels Cotrasnport w/Cl Via proton pumps