Unit 3 Flashcards
Interacalated discs
Dark areas crossing cardiac muscles, all membrane fuses forming gap jxn
Preload
Volume of blood in L.vent after diastole before being contracted - degree of tension on muscle when it begins to stretch - EDV
Afterload
Pressure against L.vent wals after contraction = aortic pressure
EDV
vol of blood in vent end of diastole or right before contraction/systole , and begining of filling = 140mL
Ejection fraction
fraction of EDV ejected 60%
Stroke Volume
Vol of blood pumped from L.vent of heart / beat 70mL
Refractory period
Period where heart cardiac muscle can’t be re-excited
Incissura
Occurs in aortic P curve, aftert he systole, due to small amount of blood backrushes in the L.vent before the valve has time to close
Frank starling mech
Intrinsic ability for heart to detect stretching and adapt to increasing volume of blood, which causes stronger contractile force and higher blood vol pumped
Cardiac cycle
begin of 1 beat to end.
Begin at sinus node, period of relaxation -diastole - contraction systole then systole
a- atrial contraction
c-begin vent contract
v-end of vent contract
period of rapid filling vent and isovolumic contract
Nervous control
parasymp - vagus nerve control, stim release of ach that decreases rate of firing of S-A nodes and dec excitability of heart, can dec 50%
Symp - using symp nerves , cause n.e which inc ca permeab and that causes contract and s-a node to fire more - can inc 340%
Ventricular escape
After ventricles stop getting signals to contract, a small portion of the purkinje fibers are able to develop a rhythm of causing contraction once again
EKG parts
p- atrial depol - being contract
QRS - ventricular depol and begin contraction also atrial Twave diastole happens behind it
T- ventricular repol
Q-T interval
Period of ventricular contract
