Digestion 2 Flashcards

1
Q

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

A

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

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2
Q

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

A

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

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3
Q

Where do cephalic reflexes originate?

A

CNS

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4
Q

Name 3 places secretions can be released

A

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

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5
Q

What do serous acini secret?

A

amylase

lipase

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6
Q

What do mucous acini secrete?

A

mucous

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7
Q

What do ducts cells secrete?

A

Water and HCO3

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8
Q

What is secreted alongside mucous and why?

A

Bicarbonate to buffer gastric acid to prevent damage to epithelium

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9
Q

What stimulates secretion of HCl and intrinsic factors?

A

Acetylcholine
Gastrin
Histamine

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10
Q

What cells secrete HCl and what is HCls function?

A

Parietal cells

HCl activates pepsin and kills bacteria

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11
Q

What cells secret intrisic factors and what is IFs function?

A

Parietal cells

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

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12
Q

What cells secrete Histamine and what is Histamines function?

A

Enterochromaffin like cell

Stimulates gastric acid secretion

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13
Q

What does Acetylcholine stimulate the release of in the stomach?

A
Hcl
Intrinsic Factor
Histamine
Pepsin
gastric lipase
gastrin
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14
Q

What cells secrete Pepsin and what is Pepsins function?

A

Chief cells

Digests proteins

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15
Q

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

A

Chief cells

Digests fats

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16
Q

What cells secrete Somatostatin and what is Somatostatins function?

A

D cells

Inhibits gastric secretion

17
Q

What cells secrete Gastrin and what is Gastrins function?

A

G cells

Stimulates gastric acid secretion

18
Q

What controls the long reflexes?

What makes up the ENS ‘little brain’

A

Autonomic control

Sensory receptors and neurons- inter-neurons- enteric neurons

19
Q

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

A

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

20
Q

G cells/ Gastrin

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

A

Stimulus= peptides, aa, neural reflexes

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

21
Q

Cholecystokinin / CCK

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

A

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

22
Q

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

A

Stimulus- Fasting released every 1.5-2 hours

Target- gastric and intestinal smooth muscle.

23
Q

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

A

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

24
Q

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

A

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

25
Q

What 2 things promote satiety?

A

GLP-1

CCK

26
Q

What is amylase broken down into?

A

Maltose

27
Q

Describe the enzyme and product for the breakdown of Maltose

A

Maltase breaks maltose into 2 glucose molecules

28
Q

Describe the enzyme and product for the breakdown of sucrose

A

Sucrase breaks sucrose into 1 glucose and one fructose

29
Q

Describe the enzyme and product for the breakdown of lactose

A

Lactase breaks lactose into one glucose and one galactose

30
Q

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

A

Transporters

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

Fructose enters on GLUT5 and exits on GLUT2

31
Q

Name the 2 types of peptidases

A

Endopeptidases

Exopeptidases

32
Q

Name examples of endopeptidases

A

Pepsin

Trypsin

33
Q

Which bonds to endopeptidases break?

A

Internal peptide bonds

34
Q

What bonds do exopeptidases break?

A

Terminal peptide bonds to release amino acids

35
Q

Match the peptide size to the mode of protein absorption.

Amino acid
Di-tripeptide
Small peptides

H+ cotransport
Endo/exocytosis
Na+ cotransport

A

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

36
Q

Describe how lipids are digested

A

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

37
Q

Describe iron absorption

A

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

38
Q

Describe calcium absorption

A

paracellualr is not regulated

Ca2+ moves into membrane vai Ca channel then exits w/ ATP of as 3Na+ goes in

39
Q

Name the 3 ways NA enters the cell

A

Na channels
Cotrasnport w/Cl
Via proton pumps