Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Year 1: Alimentary System > 5. Ions, Vitamins and Minerals > Flashcards

5. Ions, Vitamins and Minerals Flashcards

1
Q

What do cell membranes act as?

A

Diffusion barrier, enabling cells to maintain cytoplasmic concentrations of substances different from their extracellular concentrations

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

What is paracellular transport?

A

Transport through tight junctions and lateral intercellular spaces

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

What is transcellular transport?

A

Through the epithelial cells

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

What do tight junctions prevent?

A

Movement of proteins from the apical side to the lateral side

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

What are the two types of transport proteins?

A

Channel proteins and carrier proteins

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

What are the two forms of ion channels?

A

Closed and open

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

How can ion channels be gated?

A

Voltage gated, Ligand-gated (intra and extracellular) and mechanically gated

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

What are the two types of carrier-mediated transport?

A

Uniport, Coupled transport (symport and antiport)

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

How much water presented in the GI tract is absorbed?

A

99%

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

What powers the abosrption of water?

A

absoption of ions

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

Where is the most water absorbed

A

Small intestine - jejunum

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

How many litres of water is absorbed in the small intestine? a day

A

8 litres

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

How many litres of water is absorbed in the large intestine per day?

A

1.4 litres

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

Where and how much water is absorbed in a day?

A

Ingest - 2L

Saliva - 1.2L

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

How much water does the small intestine absorb?

A

8L

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

How much water does the colon absorb?

A

1.4L

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How is water absorbed?

A

Standing gradient osmosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How is water absorbed?

A

Standing gradient osmosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is standing gradient osmosis driven by?

A

Na+, which is transported from the lumen into enterocytes raising intracellular sodium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How is Na+ transported into cells?

A

Proximal bowel - Na+/H+ antiporter, Jejunum - Na+/glucose symporter, Na+/aa symporter
Ileum Na+/Cl- symporter
Colon - Na+ transporter

These all increase the intracellular concentration of sodium in the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How does Cl- diffuse into cells?

A

Cl-/HCO3- antiporter

Na+/Cl- symporter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How does K+ diffuse?

A

It diffuses in via paracellular pathways in the small intestine and leaks out between cells in colon. Passive transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What happens to Na+ inside of the cells?

A

It is pumped out by Na+/K+ ATPase resulting in an increase in the intercellular concentration of sodium.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What effect does the increase in Na+ concentration have on negative ions?

A

In draws Cl- ions and HCO3- ions from the cell into the intercellular space. Overall there is an increase in the ion concentration in the intercellular space.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How does an increase in ion concentration in the intercellular space affect the solution?

A

The solution becomes hypertonic drawing water in from the lumen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What affect does water have in the intercellular channels?

A

It increases the hydrostatic pressure resulting in the movement of ions and water across the basement membrane of the epithelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Where is Ca2+ absorbed?

A

Dudoenum and Ileum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What happens when Ca2+ diet is defiecient

A

Increases the guts ability absorb

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What stimulates Ca2+ absoption?

A

Vit D and parathyroid hormone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

How is Ca2+ carried across the apical membrane?

A

1) intestinal calcium-bining protein (IMcal) - facilitated diffusion
2) Ion channel

31
Q

How is the Ca2+ concentration kept low intracellularly?

A

By binding Ca2+ to calbindin in cytosol preventing its action as an intracellular signal

32
Q

How is Ca2+ pumped across basolateral membrane?

A

Plasma membrane Ca2+ ATPase
PMCA has a high affinity for Ca2+ (but low capacity)
Ca2+ can also be exchanged for sodium

33
Q

What effect does pumping Ca2+ across the basolateral membrane have?

A

It maintains the low intracellular concentration

34
Q

What is essential for Ca2+ absorption?

A

Vitamin D

35
Q

What does deficiency of vitamin D cause?

A

Rickets and osteoporossis

36
Q

Why is iron useful biologially?

A

Acts as an electron donor and an electron acceptor

37
Q

What is the process of iron critical for?

A

Oxygen transport

Oxidative phosphorylation

38
Q

What iron can you absorb?

A

Fe2+ not Fe3+

39
Q

List iron present in the diet?

A

1) Inorganic iron

2) As part of heme

40
Q

What reduces Fe3+ to Fe2+?

A

Vitamin C

41
Q

How is heme absorbed into the enterocyte?

A

Heme carrier protein 1 (HCP-1) and via receptor mediated endocytosis

42
Q

How is Fe2+ libereated from heme?

A

Heme oxygenase

43
Q

How does Fe2+ move into the blood from the basolateral membrane?

A

Via ferroportin

44
Q

What happens to Fe2+ when it reaches the blood?

A

Converted back to Fe3+ by hephaestin.

45
Q

What does Fe3+ bind to in the blood

A

apotransferrin

46
Q

What is the Fe3+ apotransferrin complex called?

A

Transferrin

47
Q

In the duodenum how is Fe3+ reduced to Fe2+?

A

Duodenal cytochrome B

48
Q

What is the major iron regulating protein?

A

Hepcidin -supresses ferroportin

49
Q

What is ferritin?

A

A globular protein complex capable of storing up to 4,000 iron ions. Fe2+ is oxidised to Fe3+ which crystallises in the protein shell.

50
Q

How is ferritin produced?

A

Fe2+ binds to apoferritin in cytosol

51
Q

What are vitamins?

A

Organic compounds that cannot be manufactured by the body

52
Q

What are the fat soluble vitamins?

A

A, D, E, K

53
Q

What vitamin does the liver have a lage store of?

A

B12 (2-5mg)

54
Q

What does the impaired absorption of vitamin B12 cause?

A

Retarded maturation of RBC - pernicious anaemia

55
Q

How is the denaturation of B12 in the stomach avoided?

A

Binds to R protein (haptocorrin) released in saliva and parietal cells

56
Q

Where are R proteins digested?

A

Duodenum

57
Q

What binds to vit B12 in the small intestine (duodnum)

A

IF - B12/IF complex is resistant to digestion

58
Q

What does the vit B12/IF complex bind to?

A

Cubilin receptor in the distal ileum where it is absorbed

59
Q

Once in the cell what happens to vit B12/IF complex?

A

Broken down possibly in the mitochondria

60
Q

How does B12 cross the basolateral membrane?

A

Transcobalamin II

61
Q

How does the vit B12 travel to the liver?

A

Bound to TCII

62
Q

How does the liver take up the complex of vit B12?

A

TCII receptors, then protelysis breaks down TCII

63
Q

What are channel proteins?

A

Form an aqueous pore allowing specific solutes to pass across the membrane

64
Q

What are carrier proteins?

A

Bind to the solute and undergo a conformational change to transport it across the membrane

65
Q

Which transport protein is faster - Carrier or channel?

A

channel

66
Q

What is the difference between primary and secondary active transport?

A

Primary active transport uses ATP to power transport whereas secondary active transport uses energy derived from the concentration gradient of another substance

67
Q

What are examples of a primary active transporter?

A

Na+/K+ ATPase

H+/K+ ATPase

68
Q

What are examples of a secondary active transporter?

A

SGLT-1 co transporter
HCO3-/Cl- counter trasnport
Na+/H+ Counter transporter

69
Q

What are examples of facilitated transport?

A

GLUT-5 and GLUT-2

70
Q

How are many ions absorbed?

A

Slowly by passive diffusion

71
Q

What does 1,25-dihydroxy D3 do when taken up by enterocytes?

A

Enhances Ca2+ transport through the cytosol
Increases calbindin levels
Increases the level of Ca2+ ATPase in the basolateral membrane

72
Q

How are fat soluble vitamins transported to the lumen in the GI tract?

A

In micelles

73
Q

What is the function of ferritin?

A

Binds many irons and transports it in the intestinal lumen so it can be excreted in the faeces

Year 1: Alimentary System (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions