L4 - Cell Homeostasis Flashcards Preview

BMS242 Core Phys Pharm > L4 - Cell Homeostasis > Flashcards

Flashcards in L4 - Cell Homeostasis Deck (58)
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1

Normal Na IC

10-15 mM

2

Normal Na EC

145-150 mM

3

Why must Na levels be carefully controlled

To drive other secondary active processes inside of the cell

4

Give an example of a secondary active process in the cell which relies on the Na gradient

NHE

5

What process is NHE involved in

Acid extrusion

6

What is the function of the thick ascending limb

To absorb Na and Cl in preference of water. NKCC2 cotransporter relies on the inward gradient for Na movement to couple inward movement of Cl (x2) and K.

7

What is the transepithelial osmotic gradient responsible for

Counter current multipllication

8

If IC Na levels were high in the TAL what would happen?

NaCl reabsorption would be inhibited
Transepithelial osmotic gradient is dissipated

9

Ena

+60 mV

10

Ek

-70/80 mV

11

Vm resting

-70 mV

12

In all cells there is a ____________________________ for Na

Chemical and electrical gradient

13

In an electrically excitable cell what would be the effects of increased IC Na

Decrease in inward gradient for Na
Ena would drop
Electrical driving force for Na influx decreases
Takes longer for action potentials to develop
Peak of action potential lower
Slower conductance of action potentials

14

Sum up the Na/K ATPase

3 NA OUT
2 K IN
USING ATP HYDROLYSIS

15

Model of action of the Na/K ATPase

Na binds to cleft on pump
Hydrolysis of ATP
Phosphoylation of pump
Conformational change - binding cleft exposed to the extracellular side of the cell
K binds to binding domain
Dephosphorylation
Conformational change - binding domain exposed to thee intracellular environment
K released inside of the cell

16

What can be said about the rate of the Na/K ATPase

It is a saturable function of Na i and K o

17

What does a saturable function mean

It will plateau and saturate when working at its max rate

18

What also does the Na/K ATPase rely on

ATP

19

The dependence on ATP makes the rate of the Na/K ATPase also a

Saturable function of [ATP]

20

What type of drug inhibits the Na/K ATPase

Cardiac glycosides

21

Give some examples of cardiac glycosides that inhibit the Na/K ATPase

Ouabaine
Digoxin

22

What does the Na/K ATPase maintain

High Na i
Low Na o

23

What are the two roles the Na/K ATPase plays in Vm determination

MINOR and MAJOR

24

What is the MINOR role of Na/K ATPase in Vm det.

It is electrogenic - net loss of + from the cell

25

What is the MAJOR role of Na/K ATPase in Vm det.

Sets up a high K IC and low K EC

Leak current is the driving force for K out of the cell
Vm --> Ek

26

Normal Ca IC

1 mM

27

1 mM to nM

1x 10^6

28

Normal Ca EC

100 nM

29

Roles of Ca inside of cells

Second messenger
Fusion of vesicles to the membrane
Contraction of muscles

30

What is the difference between Ca IC and Ca EC

1000 times difference