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physiology > transport of substance > Flashcards

transport of substance Flashcards

1
Q

ecf contains large amount of

A

sodium and chloride

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2
Q

icf contains large amount of

A

potassium and proteins

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3
Q

what are channel proteins?

A

watery spaces all the way through the molecule, allows diffusion of water and selected molecules and ions

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4
Q

what are carrier proteins?

A

they bind with molecules and have conformational change in their protein molecule then move the substance to the other side of the membrane

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5
Q

what is different in active transport than in normal diffusion in terms of movement across the membrane

A

active transport takes place with the help of carrier proteins against the concentration gradient whereas diffusion takes place through inter molecular spaces or through carrier proteins.

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6
Q

define diffusion interms of molecule a and b

A

when molecule A approaches the static molecule B, it transfers its kinetic and nuclear energy to molecule B. A slows down while molecule B gains kinetic energy

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7
Q

define simple diffusion in terms of movement of ions across the membrane

A

diffusion through membrane opening or intracellular space without interaction with carrier proteins.

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8
Q

rate of diffusion is determined by?

A

amount of substance available
the velocity of kinetic motion
number and size of membrane openings

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9
Q

the 2 pathways through which simple diffusion can occue

A

through the lipid bilayer if the molecule is lipid soluble

or through watery channels that penetrate all the way through

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10
Q

define vacillated diffusion ?

A

diffusion with the help of carrier protein

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11
Q

molecules that can pass through the lipid membrane are

A

oxygen, nitrogen, carbon dioxide, and alcohols

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12
Q

diffusion is directly propotional of lipid soluble molecules with

A

the their lipid solubility

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13
Q

aquaporins

A

the pores that allow rapid movement of water through cell membrane

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14
Q

how water passes through lipid membrane

A

through channels present in proteins that penaterate all the way through the lipid bilayer.

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15
Q

example of water transportation in body is?

A

erythrocytes, water that diffuses in each direction through rbc in each second is about 100 times as great as the volume of rbc

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16
Q

what are pores composed of and what makes them selective

A

they are composed of integral cell membrane proteins that form open tubes through the membrane and are always open
the electric charge on the pore and its diameter is what it makes it selective

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17
Q

aquaporins are selective cause

A

their pores are narrow

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18
Q

protein channel 2 important character tics

A

they are selectively permeable

the can be opened or closed with the help of voltage gated channels or ligand gated channels

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19
Q

describe the structure of potassium channel?

A

tetrameric with 4 identical protein subunits surrounding a central pore. has pore loops on the top of channel pore that has selectivity filter.

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20
Q

what does the selectivity filter of potassium channels have ?

A

carbonyl oxygens

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21
Q

function of carbonyl o2?

A

it dehydrates the k+ ions and allows it to past the channel

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22
Q

diameter of Na channel

A

0.3 to 0.5 nanometer

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23
Q

selectivity filter of NA ions have?

A

negatively charged amino acids

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24
Q

what does the -ve charged amino acids do?

A

they attarcted the small dehydrated Na Ions from the surrounding hydrating water molecules.

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25
Q

the opening and closing of gates is operated in what two ways?

A
  1. voltage gating

2. chemical ligand gating

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26
Q

how chemical gating works

A

it works when a chemical substance (a ligand) attaches with the protein which causes a conformational change or chemical bonding change inside the protein and makes the gate open or close.

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27
Q

what charge on the inside makes the Na gated to be closed?

A

-ve on the inside

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28
Q

what charge on the inside makes the K+ gates to be open?

A

+ve charge on the inside

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29
Q

example of chemical gating?

A

acetylcholine

30
Q

the pore that acetyl choline opens is what diameter and allows what ions to move past?

A

0.65 nanometer and allows +ve and uncharged ions to pass through

31
Q

the difference between simple diffusion and facillated diffusion?

A

the rate of simple diffusion increases with the concentration of the diffusing substance but facilated diffusion reaches Vmax and stops.

32
Q

substances that can cross cell membrane through facillated diffusion are

A

glucose and amino acids

33
Q

what is GLUT

A

proteins that transport glucose and 14 members of this family has been discovered

34
Q

what other substances does GLUT transport other than glucose

A

fructose and galactose.

35
Q

characteristic of GLUT 4

A

activated by insulin and increases the rate of glucose diffusion by 10-20 fold in insulin sensitive tissues

36
Q

rate of net diffusion?

A

concentration of inside - concentration of outside

37
Q

the rate at which the substance diffuse inwards in equal to?

A

concentration of the substance to the outside

38
Q

what the nernst equation ?

A

the electrical diff that will balance out the concentration diff of univalent ions can be determined by nernst equation.

39
Q

formula of nerst equation is

A

emf in millivolts = +- 61 c1/c2

40
Q

capillary pressure is?

A

20 mm HG higher in inside than outside

41
Q

effect of pressure difference across the membrane

A

greater number of molecules striking the membrane per second on side than the other this result in increased amount of energy available to cause a net movement of molecules from high pressure to lower pressure

42
Q

osmotic pressure

A

the pressure required to stop osmosis is called osmotic pressure

43
Q

osmotic pressure is determined by?

A

the number of particles per unit volume of fluid not by the mass of particles.

44
Q

one osmole is?

A

1 gram molecular weight of osmotically active solute.

45
Q

in primary active transport energy is derived from?

A

directly from ATP or some other high energy phosphate compound.

46
Q

in secondary active trans the energy is derived from?

A

energy is stored in the form of ionic concentration difference of secondary molecules or ions on the both side of the membrane

47
Q

primary active transport, transports what ions

A

Na, K+ , hydrogen, calcium and chloride

48
Q

carrier protein of NA/K pump has how many globular proteins?

A

2 aplha and beta

49
Q

the sizes of alpha and beta are?

A

100,000 and 55,000

50
Q

how many binding site for Na on the large globular protein?

A

3 on the inside

51
Q

binding site for K+ ?

A

2 on outside

52
Q

inside portion where Na ions bind also have

A

Atpase

53
Q

how K and Na is transported explain

A

the two K ions bind to the outside and three Na ions bind to the inside, which makes ATPase to function and it splits atp into adp and liberating high energy phosphate bond which causes a conformational change in the carrier protein extruding 3 na to outside and 2 K to inside

54
Q

how atp can be produced from na/k pump

A

when the electrochemical gradients for NA and K ions are increased that the energy stored in their electrochemical gradient is higher than the chemical energy of atp, these both ions move down their concentration gradient and make atp with adp and phosphate

55
Q

the normal mechanism to prevent the bursting of swell is done by what? and how

A

na/k pump
the pump extrudes 3 na ions outside and 2 K ions inside
the membrane is far less permeable to Na ions so the ions outside the cell will remain there which makes a net loss of ions and makes water to diffuse out through osmosis.

56
Q

caclium concentration

A

its less in the intercellular cytosol than outside. about 10,00 times less

57
Q

how CA level is kept less in the cytosol

A

the cell membrane pumps ca to the outside

the call membrane pumps calcium to other intracellular vesicular organelles like sarcoplasmic reticulum.

58
Q

why Na k+ pump is electrogenic ?

A

it transports 3 Na ions to outside and 2 K+ ions inside overall transporting one +ve charge to outside making the inside negative and causing an electric potential across the membrane

59
Q

hydrogen transportation is important at what places?

A

gastric glands of stomach

and late distal tubules or cortical collecting duct of kidneys

60
Q

what cells of gastric glands has the most potent mechanism of active transport of hydrogen?

A

parietal cells.

61
Q

what is the need of H2 ions in gasrtric glands?

A

to make hcl

62
Q

how hcl is secreted in gastric glands of stomach

A

the at secretory ends of the parietal cells of stomach the concentration of H ions are increases to a million fold which are then released into the stomach with chloride ions

63
Q

what cels in kidneys H2 is transported to?

A

intercalated cells in the late distal kidney tubules and cortical collecting ducts

64
Q

how H IONS are secreted

A

the H ions are secreted from blood into the renal fluid for eliminating excess h ions from blood

65
Q

what is co-transport

A

high conc of Na ions outside the cell keep wanting to diffuse inside, the diffusion energy of Na can pull other substances along with Na to the inside

66
Q

how co transport works

A

this works through a carrier protein which has 2 binding sites one for the Na and one for the other substance to be co-transported. once they both attach the energy gradient of na causes them to be transported to the interior together

67
Q

counter transport ?

A

na again wants to diffuse inside but this time the other substance wants to diffuse to the outside. Na binds to carrier protein protruding to the outside and the other substance binds to the carrier proteins protruding to the inside, conformational change occurs in the carrier proteins and transports na and the other substance to the interior and exterior respectively

68
Q

co transport of glucose and sodium important for

A

transporting glucose across renal and intestinal epithelial cells.

69
Q

2 important counter transports are

A

sodium calcium and sodium sodium hydrogen

70
Q

sodium hydrogen counter transport happens where

A

proximal tubules of the kidney

71
Q

Na-H counter transport in kidneys happen from where to where

A

Na moves from the lumen of the tubules into the tubular cells and H ions move from the tubular cells to the lumen

72
Q

active transport through cellular sheet occurs through

A
  1. intestinal epi
  2. epi of renal tubules
  3. epi of all exocrine glands
  4. epi of gall bladder
  5. membrane of choroid plexus of brain

physiology (25 decks)

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