4 Electrical and Molecular Mechanisms in the heart and vasculature Flashcards
At rest what ion are cardiac myocytes mainly permeable too?
Potassium ions
Why is the RMP of the cardiac myocyte not the same as EK?
EK= -95
RMP = - 90mV to -85mV
The difference the membrane having a very small permeability to other ion species at rest
What are different phases of a ventricular action potential?
4 - RMP due to background potassium ions
0 - Upstroke due to opening of voltage gated sodium channels and sodium influx
1 - initial repolarization due to potassium channels opening
2 - plateau due to opening of calcium channels and balancing of currents
3 - Repolarization due to efflux of potassium ion through voltage gates potassium channels and others
Draw the ventricular action potential
Good work
Draw the SA node action potential
Niceee
What is the name for the initial slope to threshold on the SA node action potential?
The funny current
Talk to me about the funny current
- activated at membrane potentials more negative than 50mV
- the more negative the more active it is
- due to HCN channels
What is the full name of the funny current channels
Hyperpolarisation activated cyclic nucleotide gated channels
What is responsible for depolarization and repolarization phases of the SA node AP?
Upstroke due to voltage gated sodium calcium chanels
Repolarization due to Voltage gated potassium channels
Why did would it not be a good idea to use voltage gated sodium channels as the channel of choice foe the upstroke?
they would forever be inactivated, doesn’t ever become negative enough for them to work again
In terms of action potentials describe bradycardia?
AP fire to slowly
In terms of action potentials describe asystole?
AP fail
In terms of action potentials describe tachycardia?
AP fire to quickly
In terms of action potentials describe fibrillation?
Electrical activity becomes random
What is the normal potassium range?
3.5-5.5
