Flashcards in L4 - Cell Homeostasis Deck (58)
Loading flashcards...
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
