RMP Flashcards
Define rmp
the pd between the inside and outside of a cell that isn’t stimulated into action
Rmp for Smooth muscle Skeletal muscle Cardiac muscle Nerve cell
- 50mV(unstable)(-30to-55)
- 90mV
- 90mV
- 70mV
ICF
Proton or no proton
Electron or no electron
Alkaline or acidic
Proton free
Electron free
Alkaline
Ionic ways to fat RMP
K efflux(major contributor) Na/k Atpase( less contributor) Cl influx (least contributor)
Why is Cl influx not contributing much to the Rmp generation
Cl influx contributes very little because of the repulsion effect
Why isn’t Na influx making much of a difference
because it’s not as fast. K is 100 times more permeable
Equilibrium potential of ions
When the rate of leaving is equal to coming in
Rmp of a large neurone = E_
Rmp of a small neurone= E_
Rmp of cardiac muscle = E_
Ek
Ecl
Ek
Equation to measure rmp is?
Nernst Goldman’s equation
A strength -duration curve plots - against -
Intensity on Y
Time on X
AP or no-AP Subthreshold for extended time Subthreshold for the right time Subthreshold for a short time Threshold for a short time Threshold for extended time Threshold for right time Suprthreshold for short time Supra threshold for right time
No No No No Yes Yes No Yes
Stimulus intensity is also called-
Stimulus duration is also called-
Rheobase
Utilization time
Index of excitability is -
Chronaxie
Chronaxie is measured in ?
Time (s)
High chronaxie values means?
The stuff isn’t very excitable
Which stimulus produces local response/electrotonic potentials
Subthreshold stimulus
Nerve cell can be fatigued
T/F
F. It can’t be fatigued
A transmission process can be fatigued tho
How to fix a fatigued transmission?
Make the cell rehogenic
Temporal and spatial summation
Define
Temporal:succession(common in pns)
Spatial:simultaneous (common in cns)
Range of absolute refractory period
From start of depolarization to 1/3 of repolarization
Duration of absolute refractory period in mammalian nerve
0.4-1msec
Reason for Absolute refractory period
this is due to the sodium gates already being engaged and therefore unresponsive
Range of relative refractory period
From 1/3 of repolarization to start of after-depolarization
What type of stimulus can fire an AP during relative refractory period
Suprathreshold stimulus
Why must the stimulus in RRP be Suprathreshold
because there are numerous activated K channels causing hyperpolarization
Stimulus artifacts is produced by the nerve
F. It’s a product of human intervention
Define latency period
Isopotential interval from artifact point to start of AP
Effect of changing distance between recording and stimulating electrode on latency period
Increase distance, increase latency period which would reduce speed of conduction
RMP can be measure with -
AP can be measured with - or -
Erm
IRM or erm
Skeletal ,cardiac,nerve , smooth muscle
Arrange in order of decreasing spike duration
Cardiac 300msec
Smooth 50msec
Skeletal 2-5msec
Nerve. 1msec
Which is more prominent?
After depolarization or after hyperpolarization
After hyperpolarization
Duration of the after potentials in a neurone
After depo- 4ms
After hyper-40ms
Spike potential and after potential are independent of each other
T/F
T. Change in one doesn’t affect the other
In generating AP in a neuron, is the peak reached?
No. The peak is Ena (60mV) but it usually stops at 40mV due to sodium gates closing and repulsion (++)
Duration of SA node AP
250msec
Difference between SA node AP and cardiac AP
Initial depo is by rapid Ca not rapid Na
Pre potential is by slow Na gates
How to maintain cardiac AP
By activity of Na/K atpase
Z^3
If sodium doubles, Na/k activity increases by 8folds
Mentions 3 waves that are imposed on rmp in smooth muscles
Spike, slow waves and pacemaker potentials
Slow waves is independent of nerve supply
T/F
T. It’s by ENS
Spikes can only occur during depo phase of slow waves
F. Can occur at any phase
Spikes have variable peak potentials
T/F
T
Excitation-contraction effect in smooth muscle
Slow
Contraction starts 200ms after excitation (spike)
Ends 150ms after spike is over
Peak contraction is 500msec after spike starts
excitation-contraction effect in cardiac and skeletal muscles
Less than 10msec
SALTATORY and ELECTROTONIC Conduction of AP
Myelination
Movement
S: myelinated and jumps from node to nodes;dense Na channels at nodes and least at soma ; Na is flanked by K
E: unmyelinated;must occur at every point of the nerve
