Action Potentials Flashcards
1
Q
- Passive electrical transmission? Need what?
- 4 steps of AP?
- Ena? Ek?
- Resting membrane equation? Pr=?
- Membrane more permeable to?
- Initial small depolarization must have? Leads to? (2)
A
- Inadequate for long distances; Na+ channels
1. ) Resting: Na+/K+ return cell to baseline
2. ) Depolarization: Initial small depol. causes influx of Na+
3. ) Repolarization: Na+ channels close; K+ channels open
4. ) Hyperpolarization: K+ channels overshoot and close - +60; -90
- Vm = 60 log ( [K]o + PR * [Na]o ) / ( [K]I + PR * [Na]I) ; PR = PNA/PK
- Potassium
- In flow of Na+> out flow of K+; + feedback loop/ all or none response
2
Q
- Structure of voltage gated Na channels?
- Progression? (4) Refractory due to?
- What happens with hyperkalemia?
- Refractory period? Prevents? Absolute? Relative? Na Channels? K Channels?
- Na+/K+ in short term?
- 3 problems with passive progression? How each effects spread? Analogy?
Equation?
A
- m gate and h teather
- 1.) m closed 2.) both open 3.) h closed 4.) both closed; time for H to open
- Ek increases and membrane is deoplarized which leads to decreased AP’s
- initiation of AP is difficult; AP’s reversing direction; AP is impossible; AP unlikely; inactivated; open
1. ) Internal resisitance: decreases spread; sand in hose
2. ) Membrane resistance; increases spread; leaks in hose
3. ) Membrane capacitance: Decrease spread; flexibility of hose - lambda (distance travelled when voltage has dropped to 37% initial) = 0.5 sq rt. Rm/Ri
3
Q
- Active propogation depends on?
- Effect of myelin?
- What increases conduction speed? (2)
- Saltatory conduction possible via?
- 2 demylenating diseases?
- Why are Na pumps 5-10x greater than necessary? (3)
- Types of neurotoxins? (2) Ex? (3)
- How does lidocaine work?
- Steps in heart AP? (5)
A
- Na voltage channels
- Increase Rm and decrease Cm
- Diameter and myelin
- Nodes of Ranvier
- 1.) MS = damage to myelin in CNS
2. ) Guillan-Barre = Immune response against myelin of muscles axons - branching, decrease refrac. period, safety
1. ) Block Na+ channels: Tetrodoxin; saxitoxin
2. ) Alter ion selectivity of Na channels: Batracholtoxin - Binds intracellular part of VG na channels
1. ) Na in 2.) K+, Cl- out 3.) Ca in, K out 4.) K out 5.) Resting
