L23 - GI Digestion And Absorption Flashcards

1
Q

What is digestion? (2)

A

Sequence by which food is broken down and chemically converted
- to be absorbed by cells of an organism
- used to maintain vital bodily functions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the cells involved in the secretion in the salivary glands? (4)

A
  • myoepithelial cells
  • serous cells
  • duct cells
  • mucous cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What do serous cells secrete? (2)

A
  • amylase
  • lingual lipase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does amylase do? (2)

A
  • breakdown of carbohydrates
  • brief, inactivated in acidic conditions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does lingua lipase do? (4)

A
  • breakdown of trigkycerides (fat)
  • optimal at pH 4-5
  • continues throughout GI tract
  • important in newborns
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the types of cells in the stomach that secrete? (4)

A
  • parietal cell
  • chief cell
  • mucous cell
  • G cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What do parietal cells do? (2)

A

secretes HCl
- denatures protein
- pepsinogen to pepsin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What do chief cells do? (2)

A

Secrete pepsinogen
- converted to pepsin
- protein digestion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What do mucous cells do? (2)

A
  • protection
  • lubrication
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What do G cells do?

A

Produce gastrin
- controls HCl, motility, pepsin, muscous

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the gastric acid secretion? (2)

A

HCl (~2.5L/day)
- stomach pH 2-3
- optimal for pepsin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is gastric acid secretion stimulated by? (3)

A
  • histamine
  • gastrin
  • ACh
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is contained within the storage vesicles? (3)

A
  • trypsinogen
  • chymotrypsinogen
  • procarboxypeptidases
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What happens to the - trypsinogen, chymotrypsinogen, procarboxypeptidases released?

A

Broken down by eneteropeptidases on the brush border
= activates them

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What else is secreted in the pancreatic secretion? (4)

A
  • amylase - starch - active
  • lipase - fat - active
  • RNAase
  • DNAase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is secreted from the gall bladder?

17
Q

Where is bile formed in, stored and concentrated, and released into? (3)

A
  • liver from cholesterol in diet
  • gallbladder
  • into SI
18
Q

What controls the digestive process? (3)

A
  • Stretch receptors - send signals to brain, triggers secretion of digestive juices
  • Stomach - gastrin, promotes production of stomach acids
  • Intestine - releases secretin and cholecystokinin, stimulates secretion of pancreatic juice and bile
19
Q

What routes of absorption are there? (2)

A
  • Lipids - to lymph lacteal
  • Sugars and a/a - to portal blood supply
20
Q

What are the mechanisms of absorption? (2)

A
  • active transport
  • carrier-mediated (facilitated) transport
21
Q

What is protein digestion?

A

Proteases catalyse hydrolysis of a/a

22
Q

What are the main proteases? (3)

A
  • pepsin in stomach
  • trypsin, chymotrypsin from pancreas
  • peptidases in intestinal brush border
23
Q

Where does protein absorption occur?

A

In the SI
(Active transport of tripeptides, dipeptides and a/a)

24
Q

What is carbohydrate digestion? (3)

A
  • Mouth - begins, salivary amylase
  • Stomach - denatures amylase
  • SI - pancreatic amylase - digested by intestinal brush border enzymes
25
What happens in carbohydrate absorption? (3)
- enzymes on luminal surface of SI epithelial cells digest disaccharides into monosaccharides - absorbed by facilitated diffusion or active transport with Na+ - leave epithelial cells by facilitated diffusion, enter blood, distributed throughout body
26
What is the main site of fat digestion?
Small intestine
27
What is fat digestion critically dependent on? (3)
- secretions from the liver and pancreas - emulsification required - bile and lipase involved from gallbladder and pancrease
28
What are the sequence of steps in fat absorption? (5)
- FA & monoglycerides pass through epithelial cell layer - converted to triglycerides - combine with cholesterol, phospholipids, protein = chylomicron - water soluble, enters lacteal - transported from lacteal to bloodstream
29
What occurs at the stomach for oral drug absorption?
Disintegration and dissolution - by acid environment and mechanical churning
30
How is the drug absorbed in oral drug absorption? (3)
- passive diffusion - facilitated diffusion - active transport
31
What is oral drug absorption determined by? (3)
- physiochemical properties - formulation - route of administration
32
What is oral drug absorption affected by? (5)
- luminal pH - SA - perfusion - bile - mucus
33
What is oral drug absorption influenced by?
Intestinal transit time
34
What does enteric coating do? (2)
- prevents formulation from gastric fluid in stomach - release drug component in intestinal region
35
What is the enteric coating prepared from?
Gastric resistant polymers - insoluble at low pH
36
What is drug releaae controlled by?
pH
37
How does enteric coating help? (4)
- prevents gastric distress/nausea due to irritation - protect acid-labile drugs - delivers drugs intended for local action at intestine - provide delayed release compounds