PSC1002/L29 Stomach Flashcards

1
Q

Give 3 functions of the small intestine.

A

Digestion
Nutrient absorption
Electrolyte absorption
Water absorption
Secretion

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

Which enzyme is involved in luminal digestion of starch-type polysaccharides?

A

Amylases

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

Which enzymes are involved in membrane digestion by disaccharidases? (3)

A

Maltase
Sucrase-isomaltase
Lactase

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

Why is amylase described as an endo-enzyme?

A

It can only break internal bonds so cannot produce monosaccharides

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

Give 2 transporters of the apical membrane.

A

SGLT1
Glucose, galactose
Na+ coupled, secondary active transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Give a transporter of the basolateral membrane.

A

GLUT2
Facilitated diffusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Give 3 types of protein digestion and their related enzymes.

A

Luminal digestion by gastric and pancreatic proteases
Membrane digestion by brush-border peptidases
Cytosolic digestion within epithelium of small peptides

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

Give 2 substances absorbed in the small intestine.

A

Amino acids
Peptides
Intact protein absorbed in antigenic quantities

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

Describe digestion by gastric pepsin. (2)

A

10-20% digestion
Endopeptidases

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

Describe digestion by pancreatic peptidases. (3)

A

E.g., trypsin
Endopeptidases and exopeptidases
Short peptides (2-6AA) and free amino acids

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

Describe protein digestion by membrane and cytosolic peptidases. (3)

A

Endo, exo or dipeptidases
Many different types
Free amino acids

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

What is acid microclimate used for?

A

Peptide absorption
H+ coupled di/tripeptide transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What follows peptide absorption?

A

Cytosolic peptide digestion or export by unknown basolateral transporter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Give 3 drugs which utilise peptide carriers.

A

Angiotensin-converting enzyme (ACE) inhibitors
B-lactam antibiotics
Prodrugs (Val-acyclovir)

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

Give 3 types of amino acid transporters.

A

Neutral
Cationic
Anionic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Give the function of the apical membrane in amino acid absorption. (3)

A

Mainly coupled to ion uptake
Secondary active transport
Accumulation within epithelial cells

17
Q

What is the role of the basolateral membrane in amino acid absorption?

A

Mainly facilitated diffusion

18
Q

Give 3 key points in lipid digestion and absorption.

A

Low water solubility
Solubilisation
Digestion
Absorption
Re-esterification of fatty acids
Transport to blood

19
Q

Describe triglycerides (dietary lipids).

A

Triesters of glycerol and long-chain fatty acids

20
Q

Describe phospholipids (dietary lipids).

A

Subsitute 1 fatty acid chain with phospho-ester of organic base

21
Q

Describe short chain fatty acids.

A

Minor - dairy

22
Q

Describe lipid digestion. (5)

A

Detergent emulsification
Digestion by lipases produces micelles
Diffusion into epithelial cells
Resynthesis of triglycerides
Release as chylomicrons

23
Q

Describe emulsification (stage 1) of lipid digestion. (3)

A

Begins with chewing, grinding and mixing of food
Increases oil-water interface area
Stabilised by bile salts and phospholipids

24
Q

Describe digestion (stage 2) of lipids. (3)

A

Gastric and pancreatic lipases
Co-lipase
Triglycerides to 2 fatty acids and monoglyceride

25
Q

What are micelles? (3)

A

Polymolecular aggregates 5nm
Monoglyceride, fatty acids, bile salts
Cholestrol and fat-soluble vitamins
Close approximation to enterocyte microvilli for absorption

26
Q

Describe stage 3 of lipid digestion.

A

Diffusion down gradient

27
Q

Describe stage 4 of lipid digestion.

A

Driven by re-esterification of fatty acids to triglycerides within epithelial cells

28
Q

Describe stage 5 of lipid digestion.

A

Released across basolateral membrane as chylomicrons

29
Q

How do digested lipids enter the blood?

A

Via lymph system

30
Q

What other molecules follow the same route of absorption as lipids?

A

Fat soluble vitamins (A, D, E, K)