Created by J yadonknow
over 6 years ago
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Question | Answer |
Cardiac output | CO=HR*Stroke Vol. L/min = Bpm * L |
HR stim | ANS (Para)sympathetic stim. Circulating hormones |
Stroke vol. stim | extrinsic: Sympathetic stim. Intrinsic: Degree of cardiac muscle stretch like endothelium derived NO or metabolites + relating factors e.g. H+/CO2/Hypoxia |
Cardiac Pacemaker | SANs generates electrical activity |
Atrium/Ventricle/SANs depolarisation | a eh ahee |
E activity pathway | SAN -> RA -> LA -> AVN (Delay) -> Bundle of His -> Septum of heart -> L/R V |
Lead II position | Bundle of His axis |
ECG reading | PQRST |
P wave | Atria depolarisation |
PR interval | Conduction through AV node |
QRS complex | Depolarisation of ventricles More cells = larger depolarisation Repolarisation of atria distorted by large depol |
T wave | Repolarisation of ventricles |
QT duration | Ventricular repo+depo |
The heart is a functional what now, sonny boy? I say young whippersnapper, the heart is a functional what now? | Functional syncytium gramps! Each individual cell cooperates with one another to create a co-ordinated wave of excitation/contraction! |
Well I'll be! Crazy how advanced science is these days. Now say now sonny boy, just how do they do that? | Well gramps it's simple, the cells are electrically coupled through gap junctions They're also mechanically coupled |
Why is relaxation co-ordinated w/ excitation? | To allow sufficient time for filling |
What do valves ensure? | One-way flow of blood |
Systole | Contraction of chamber and ejection of blood |
Diastole | Relaxation and filling |
Events of cardiac cycle | 1. Atrial systole (ventricular diastole). 2. Isovolumetric contraction of ventricles 3. Ventricular systole. 4. Isovolumetric relaxation of ventricles 5. Passive refilling of ventricles |
Diagram of valve opening shutting | Mitral valve closes Aortic valve opens Aortic valve closes Aortic pressure Left atrial pressure Mitral valve opens |
Dynamic Pressure-Volume relationship in left ventricle | A-~>B Diastole filling B~>C Isovolumic contraction C~> D Ejection of blood D~>A Isolvolumic relaxation |
PS Stim on SAN pacemaker activity | Stim vagus nerve, slows rate of depol. Slows heart rate |
S stim | Delop reaches threshold much more rapidly ^ heart rate |
Cardiac Cycle | Phase 1: Atrial systole Phase 2: Isovolumetric contraction Phase 3: Rapid ejection Phase 4: Isovolumetric relaxation Phase 5: Passive refilling |
Diastole | Phase 1 and 5 |
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