Electrophysiology & ECG Flashcards
What are conductile muscle cells ?
These cells have spontaneous electrical activity - e.g. can depolarise on their own
What is the hierarchy of control ?
SA node (pacemaker) -Send out depolarising waves to the surround muscle cells
AV node
- Located in the inter-atrial septum
- Delays SA by approx 100ms which allows atrial emptying before ventricular contraction
Bindle of His
- Located superior portion IV septum
- Serves as the connection between atria and ventricles
Conduction pathway ?
SA node AV node Bundle of His R and L branches Purkinji fibres
What are contractile cardiac muscle cells ?
- Non pacemaker
- Have stable membrane potentials
What is stroke volume and cardiac output ?
- Volume of blood ejected from heart per beat
- Volume of blood ejected per minute
Explain Ventricular systole ?
- AV valves close when ventricular pressure exceeds atrial
- Semilunar valves open when ventricular pressure exceeds aortic/puml and blood is then ejected
- Semilunar valves close when ventricular pressure falls below aortic/pulm
Explain Ventricular diastole ?
- Ventricles relax and falls below that of atrial pressure
- AV valves open and bloods fills ventricles from atria
What are brady and tachycardia ?
Brady = slower than norm HR
Tachy = Faster than normal HR
In HR regulation what is the reflex control ?
Bainbridge reflex
-Increase venous return which increases HR
Baroreceptor reflex
-Increases BP which decreases HR and contractility
Chemoreceptor reflex
-Decrease o2 or increase co2 in peripheral tissues which increases HR and resp rate
What is SV and what increases it ?
Blood output per heartbeat
(SV = EDV - ESV)
Increased ventricular filling time
Increase venous return
Decrease arterial BP
What is Frank Starling Mechanism ?
Increase preload increases contractility which increases SV
