Lecture 18: Molecular and Ionic Cardiovascular Control Flashcards
1
Q
what is the isolated / denervated heart rate
A
100 bpm
2
Q
what effect does noradrenaline have on the heart
A
- affects pacemaker channels
- via beta 1 receptor
- increases net inward current, calcium current and potassium current
3
Q
what effect do alpha 1 receptors have
A
- vasoconstriction
- sweat
4
Q
where are beta 1 and 2 receptors found
A
1: cardiac muscle
2: skeletal muscle
2: lungs
5
Q
what effect does atropine have on heart rate
A
increases it
6
Q
what role do the t tubules and terminal cisternae play in cardiomyocyte contraction
A
they’re a system of storing and releasing calcium in response to Vm
7
Q
what is excitation-contraction coupling
A
- the link between depolarisation of the membrane
- with a tiny influx of calcium
- and the consequent huge increase in cytosolic calcium
- that leads to contraction
8
Q
what can calcium overload cause and what is it exacerbated by
A
- can cause risk of ectopic beats and arrhythmias
- made worse by fast heart rates and increased sympathetic drive
9
Q
what does verapamil do
A
- not a DHP
- blocks calcium channels, more on heart than blood vessels
- slows nodal rate
- slows conduction through AV node
- used as antiarrhythmic
10
Q
what does diltiazem do
A
- not a DHP
- blocks calcium channels on both heart and vessel channels
- slows nodal rate
- vasodilates coronary arteries
- used as antianginal and antiarrhythmic
11
Q
what does digoxin do
A
- positive inotropic agent
- increases stroke volume and contractility
- slightly inhibits Na/K pump leading to increased calcium in cytosol
- stimulates vagus nerve
- improves symptoms for heart failure, but not mortality
- now used for atrial fibrillation
