LEC EXAM #2 CHP 7 Flashcards
3 types of excitable cells:
- neurons
- muscles (skeletal, smooth, and heart)
- secretory cells (pituitary, insulin producing cells of the pancreas)
How is the electrochemical gradient “established”?
Na/K ATPase pump
How is the RMP “maintained”?
- Na/K ATP ase pump
- Na leak channels
- K leak channels
What contributes to resting membrane potential?
- Electrochemical gradients (charge + concentration)
- amount of leak channels present for each ion
Has the most leak channels:
K+
What are the 4 phases for excitable cells?
- RMP (-70 mv)
- depolarization -> threshold (-55 mv)-> action potential
- repolarization
- hyperpolarization-> back to RMP
Na/K ATPase pump pumps:
3 Na+ out and 2 K+ in per ATP
Conc. of K+ inside/outside:
Inside: 150
Outside: 5
Conc. of Na+ inside/outside:
Inside: 15
Outside: 150
K+ wants to go:
Outside
Na+ wants to go:
Inside
Why does the RMP never reach -90 mv?
Due to the Na/K ATPase pump
K+ equilibrium:
-90 mv
What resets RMP?
Na v.g.c. pump + leak channels
Which voltage gated channel is used during depolarization?
Na+ v.g.c.
Which voltage gated channel closes and which is used during repolarization?
Na+ v.g.c closes
K+ v.g.c opens
Na equilibrium:
+60
Na+ voltage gated channel phases:
Open, inactive, closed
In Na v.g.c, if you don’t hit threshold of ___, you don’t get:
-55 mv
an action potential
T or F
Once an AP has been generated, the amplitude of the depolarization wave will be the same for all action potentials generated:
True
V.G.C won’t pop open if _______, once reset to _____ is when you will get a stimulus and it’ll respond
inactive
closed
Repolarization makes the inside more:
Negative
2 types of refractory periods:
- Absolute
- Relative
Absolute refractory period:
Na+ v.g.c. are inactive-> no AP possible