Regulation of intracellular pH

Question 1

what’s EC pH?

Answer 1

7.9

Question 2

what’s IC pH?

Answer 2

7.2

Question 3

how do you calculate pH?

Answer 3

-log10 [H+]

Question 4

what units is H+ in when calculating pH?

Answer 4

nM

Question 5

what are the 3 challenges of pH(i) concentration?

Answer 5

• metabolism (production of acid metabolites)
• ischemia (reduced blood flow and increased anaerobic respiration which produces lactic acid)
• -ve vM- attracts H+ into cell

Question 6

if H+ is not being actively transported in or out of cell how is it described?

Answer 6

in equilbrium with Vm

Question 7

how can the expected [H+]i be estimated?

Answer 7

nernst equation

Question 8

how is pH(i) measured?

Answer 8

using fluorescent pH sensitive indicators
put into cells
fluorescent light needed (confocal lasers) - excites electrons
- light goes throughthe objective and recorded by a camera and sent to a computer

Question 9

what are the 2 acid- extruders?

Answer 9

NHE- H+ out, Na+ in

NBC- Na+ in, HCO3 in

Question 10

what are the 2 acid loaders?

Answer 10

CHE- Cl- in, OH- out

CBE- Cl- in, HCO3 out

Question 11

what’s a greater problem for a cell- acidity or alkilisation?

Answer 11

acidity

Question 12

why must Ca2+ be really low?

Answer 12

if you have too much Ca2+ in cell- it would precipitate with phosphate to form calcium phosphate (insoluble) this would build up in soft tisues to calcify/ harden them

Question 13

what 2 mechanisms keep Ca2+ (i) rlly low?

Answer 13

• Ca2+ extrusion across cell membrane

- sequestration of Ca2+ into organelles

Question 14

in what 2 mechanisms are Ca2+ extruded out of cell?

Answer 14

• using a Ca2+, 3Na+ exchanger- unequal charge

- using ATP pump to pump calcium out and 2H+ in

Question 15

what mechanism allows Ca2+ sequestration into organelles?

Answer 15

ATP pumps 2H+ out of ER/SR and 2 Ca2+ in

SERCA

Question 16

what’s an electroneutral pump?

Answer 16

no net movement of charge e.g. Ca2+/ 2H+ exchanger

Question 17

what’s an electrogenic pump?

Answer 17

net movement of charge- generates small electrical current- e.g. Serca- 2H+ out, 2Ca2+ in

Question 18

in non-muscle cells what receptors act as a channel for calcium influx in signaling?

Answer 18

IP3 (in ER/SR) - GPCR

Question 19

in muscle cells what receptors act as a channel for calcium influx in signaling?

Answer 19

Ryanodine (in ER/SR)

Question 20

what processes are calcium involved in (5)

Answer 20

endocytosis
exocytosis
cell death
contraction 
cell division