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BMS242- Physiology and Pharmacology > core physiology > Flashcards

Flashcards in core physiology Deck (59)
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1

what is the composition of the cell membrane?

Lipids - 42%
Proteins - 55%
Carbohydrates - 3%

2

what are the three types of transporter proteins?

Carriers, Pumps and Channels

3

which transporter requires ATP?

Pump

4

name the two methods of measuring membrane potential?

patch clamp and glass electrode

5

how would you go about using the glass electrode technique?

impale cell so the tip (filled with KCl) sits in the IC compartment - measure potential with respect to referee electrode

6

which technique would have the most specificity

small electrode as much smaller with very sharp tip and insoluble thin wire

7

what is the distribution of sodium

EC - 150 IC - 15

8

what is the distribution of potassium

EC - 5 IC - 150

9

what is the distribution of large organic anions

EC - 0 IC - 65

10

describe the key features of Na/KATPase

contributes 20% directly
electrogenic - 3 Na out, 2 K in - therefore lose 1 positive charge each time
indirect IC Na and K maintained
if blocked - instantly wipes out membrane potential

11

what does electrogenic mean

produces a change in electrical potential of cell - change in voltage plus a change in permeability of membrane

12

what do K+ channels contribute to membrane potential

-ve charge created when K+ moves
creates driving force for K+ to move into cell
equal - opposite movement of K+ means equilibrium

13

what do Na+ channels contribute

same as K+ - maintain equilibrium

14

what does the Nernst equation calculate

equilibrium potential of the cell

15

what is the predictive potential of Na and K

Na - +61.5mV K - -90.8mV

16

why are the predictive values not = -70mV

because there must be some leakage going on meaning Na can get into the cell and K can leave

17

what does the Goldman equation calculate

equilibrium potential of cell with more than one ion

18

what is the relationship between pH and [H+]

increase pH doubles/halves [H+]

19

how do we measure IC pH

using 2 microelectrodes - change in voltage = change in pH

20

what are the electrodes calibrated with

pH standards

21

what are the ideal cells for microelectrodes and why

nerves, muscles, Xenopus oocytes because they are large cells

22

what could you use to calculate pH of small cells i.e. epithelia

fluorescent indicators

23

how?

load cells with inactive form (so it can pass through the membrane)
inside cell it is converted to active form
excites a light with specific wavelength - amount at 2nd wavelength is measures
fluorescence = IC pH
indicator is calibrated inside cell and membrane is permeabilised and pH of bath solution is changed

24

what are the three factors in controlling IC pH

buffers
acid loading
acid extrusion

25

what do buffers do

moderate effects of acid/alkali load by consuming/releasing protons
DO NOT PREVENT CHANGE pH!!!!

26

what do buffers rely on

COOH group and NH2 group

27

what exchanger is used for acid extrusion and hoe does it act

Na/H exchanger protein - exchanges one Na into cell for one H out

28

what does it rely on

Na gradient set up by Na/K pump

29

does high pH inhibit or activate exchanger

high pH inhibits - low pH activates

30

what happens when allosteric modification occurs

a unused proton binds the the allosteric site increasing activity