Chest Pain Flashcards
Flux (J)
=KD[^C/^x]
Fick equation
VO2 = CO x (arterialO2-venousO2)
Cardiac output equation
CO = HR x SV
Left side of the heart
systemic circulation
Right side of the heart
pulmonary circulation
Pulmonary and systemic circulation systems are in?
Series
Organs are in?
Parallel, each organ gets freshly, fully oxygenated blood, flow to one organ can be changed without affecting flow to other organs
Hemodynamic Ohm’s Law equivalent
Q = ^P/R
Resistance =
^P/CO = (MAP-CVP)/CO
MAP normal?
95mmHg
CVP normal?
2mmHg
CO normal?
5-6L/min
Blood flow is proportional to?
Pressure difference
Pressures of heart chambers
RA = 2mmHg RV = 25/10mmHg LA = 8-9mmHg LV = 130/80mmHg
Responses to drop in pressure?
- Reduced outflow (increase R) controlled by SNS 2. Increase inflow by increasing HR and contractility 3. Increase volume (short term - venous return, long term - salt and water retention increase BV)
Depolarization of the heart
SA, AV, septum (left to right), His/Purkinje system, ventricular muscle (endo to epicardium)
Fast APs vs Slow APs of heart
contracting regions (atrial and ventricular muscles), fast conduction (His, Purkinje), Left side pacemaking (SA) and slow conduction (AV) right side
Fast AP Phases
0 - rapid depol due to activation of inward Na+ current 1 - initial repol due to inactivation of Na+ channels and activation of transient outward K+ channels (Ito) 2 - plateau phase due to slow activating inward Ca++ currents, triggers CICR 3 - repol due to inactivation of Ca++ currents and activation of several different K+ currents (Iks, Ikr) 4 - resting membrane potential due to inward-rectifying K+ channels (Ik1)
Slow AP Phases
0 - slow depol due to activation of slowly-acting Ca++ channels 1 - absent 2 - absent 3 - repol due to Ca++ channel inactivation and activation of K+ channels 4 - slowly depolarizing resting potential (If - nonselective cation channel - HCN)
Absolute refractory period for fast v slow AP
Fast - Na inactivation Slow - Ca inactivation
Spontaneous depol of Slow AP
imbalance between outward K channels (Ik,ach, or Igirk) and inward current of not selective cation channel (If)
Parasympathetic stimulation on AP
PNS releases ACh, binds to muscarinic ACh receptors, increasing Igirk, reducing rate of phase 4 depol, negative chronotropic effect
Sympathetic stimulation on AP
SNS release norepi, epi, binds to b1 adrenergic repectors, increase both If and Ica, increasing phase 4 depol, positive chronotropic effect
Intrinsic rate of SA node, AV node, and His/Purkinje systems
SA = 100bpm AV = 40-60bpm His/Purkinje = 30-40bpm