for action potentials in contractile cells, phase 1 depolarization occurs due to influx of ______
Na+
What are the 2 ways to remove calcium from the cytosol?
1. SERCA pump back into SR
2. Na+/Ca2+ exchanger puts calcium back to ECF
What are the 3 stages of ventricular diastole?
1. early diastole
2. late diastole
3. atrial systole
After ventricular diastole there is ventricular systole. At the end of ventricular systole the end systolic volume (ESV) is _____ mL while the stroke volume is ________ (mL)
80 mL; 70 mL
The QRS complex corresponds to _____________ (include electrical and mechanical events)
ventricular depolarization and ventricular systole
phase 2 early repolarization/plateua is caused by a closing of ____ channels and a slow influx of _______
close Na+ channels; slow influx of Ca2+
T or F: the SA node has autonomic regulation from only the sympathetic nervous system
False. The SA node has both sympathetic and parasympathetic regulation
During isovolumetric relaxation, AV valves are (open or closed) and semilunar valves are (open or closed)
closed; closed. Isovolumetric means 'same volume', so the ventricles will have the same volume of blood--this is only possible when both valves are closed and there is no blood entering or leaving the ventricles.
During the 1st phase of ventricular systole, _______ valves close and the ventricles exhibit isovolumetric contraction, resulting in an (increase or decrease) in pressure
AV valves; increase
The T wave corresponds to ______________
ventricular repolarization (leads to ventricular diastole)
during phase 3 repolarization, _____ channels close and ______ channels open
Ca2+ close; K+ open --> efflux of K+
a negative chronotropic effect refers to a _____________ in heart rate (inc or dec)
decrease in heart rate
The ventricles are "topped off" with blood during ___________
atrial systole
What happens when the ventricular pressure exceeds aortic pressure?
semilunar valves open
cardiac output = _____ x _______
HR x SV
calcium required for contraction comes from 2 places:
1.
2.
1. ECF (20% of Ca2+)
2. SR (80%)
Sympathetic regulation of the SA node results in a(n) ____________ in heart rate and is therefore a ___________ chronotropic effect
increase; positive
The end diastolic volume (EDV) is ___ mL
150 mL of blood in the ventricles
The S1 lubb sound corresponds to closure of the _____ valves, while the S2 dubb sound is closure of the ______ valves
AV; semilunar
what influences contractility (and therefore influences ESV and stroke volume)?
levels of cytosolic calcium
calcium entering the myocyte through the L-type (slow) Ca channels binds to _________ receptors on the SR to stimulate SR calcium release
ryanodine receptors
contraction; relaxation
During late diastole the AV valves open because the pressure in the ventricles (increases or decreases) relative to the atria
decreases
The P wave corresponds to _____________ (include electrical and mechanical events)
atrial depolarization and atrial systole
Starling's principle of the heart says that a higher preload leads to a (higher or lower) stroke volume
higher stroke volume