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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
the opening and closing of gates is operated in what two ways?
1. voltage gating | 2. chemical ligand gating
26
how chemical gating works
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.
27
what charge on the inside makes the Na gated to be closed?
-ve on the inside
28
what charge on the inside makes the K+ gates to be open?
+ve charge on the inside
29
example of chemical gating?
acetylcholine
30
the pore that acetyl choline opens is what diameter and allows what ions to move past?
0.65 nanometer and allows +ve and uncharged ions to pass through
31
the difference between simple diffusion and facillated diffusion?
the rate of simple diffusion increases with the concentration of the diffusing substance but facilated diffusion reaches Vmax and stops.
32
substances that can cross cell membrane through facillated diffusion are
glucose and amino acids
33
what is GLUT
proteins that transport glucose and 14 members of this family has been discovered
34
what other substances does GLUT transport other than glucose
fructose and galactose.
35
characteristic of GLUT 4
activated by insulin and increases the rate of glucose diffusion by 10-20 fold in insulin sensitive tissues
36
rate of net diffusion?
concentration of inside - concentration of outside
37
the rate at which the substance diffuse inwards in equal to?
concentration of the substance to the outside
38
what the nernst equation ?
the electrical diff that will balance out the concentration diff of univalent ions can be determined by nernst equation.
39
formula of nerst equation is
emf in millivolts = +- 61 c1/c2
40
capillary pressure is?
20 mm HG higher in inside than outside
41
effect of pressure difference across the membrane
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
osmotic pressure
the pressure required to stop osmosis is called osmotic pressure
43
osmotic pressure is determined by?
the number of particles per unit volume of fluid not by the mass of particles.
44
one osmole is?
1 gram molecular weight of osmotically active solute.
45
in primary active transport energy is derived from?
directly from ATP or some other high energy phosphate compound.
46
in secondary active trans the energy is derived from?
energy is stored in the form of ionic concentration difference of secondary molecules or ions on the both side of the membrane
47
primary active transport, transports what ions
Na, K+ , hydrogen, calcium and chloride
48
carrier protein of NA/K pump has how many globular proteins?
2 aplha and beta
49
the sizes of alpha and beta are?
100,000 and 55,000
50
how many binding site for Na on the large globular protein?
3 on the inside
51
binding site for K+ ?
2 on outside
52
inside portion where Na ions bind also have
Atpase
53
how K and Na is transported explain
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
how atp can be produced from na/k pump
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
the normal mechanism to prevent the bursting of swell is done by what? and how
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
caclium concentration
its less in the intercellular cytosol than outside. about 10,00 times less
57
how CA level is kept less in the cytosol
the cell membrane pumps ca to the outside | the call membrane pumps calcium to other intracellular vesicular organelles like sarcoplasmic reticulum.
58
why Na k+ pump is electrogenic ?
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
hydrogen transportation is important at what places?
gastric glands of stomach | and late distal tubules or cortical collecting duct of kidneys
60
what cells of gastric glands has the most potent mechanism of active transport of hydrogen?
parietal cells.
61
what is the need of H2 ions in gasrtric glands?
to make hcl
62
how hcl is secreted in gastric glands of stomach
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
what cels in kidneys H2 is transported to?
intercalated cells in the late distal kidney tubules and cortical collecting ducts
64
how H IONS are secreted
the H ions are secreted from blood into the renal fluid for eliminating excess h ions from blood
65
what is co-transport
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
how co transport works
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
counter transport ?
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
co transport of glucose and sodium important for
transporting glucose across renal and intestinal epithelial cells.
69
2 important counter transports are
sodium calcium and sodium sodium hydrogen
70
sodium hydrogen counter transport happens where
proximal tubules of the kidney
71
Na-H counter transport in kidneys happen from where to where
Na moves from the lumen of the tubules into the tubular cells and H ions move from the tubular cells to the lumen
72
active transport through cellular sheet occurs through
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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