Cardiac Muscle Flashcards
Atrioventricular valves prevent back flow from _________ to _________ during ________
ventricles; atria; systole
Atrioventricular valves include:
Tricuspid and Bicuspid/mitral
Closure of the AV valves = the ______ heart sound
1st
Semilunar valves prevent backflow from _________ to ________ during _________
arteries; ventricles; diastole
Closure of the semilunar valves = the _______ heart sound
2nd
Heart sounds are the sound of turbulent blood flow through the valves right _________ they close
BEFORE
Stenosis means the valves are _______
narrow/rigid
Regurgitation means the valves do not _______ correctly
close
Action potentials in contractile cardiac muscle last ______ longer than skeletal muscle’s AP
15x
Action potential phases:
- 4:
- 0:
- 1:
- 2:
- 3:
- 4: at rest
- 0: rapid depolarization - upstroke
- 1: repolarization (brief)
- 2: plateau due to balance between Ca2+ & K+ currents
- 3: repolarization
Na is important for _______ ________
rapid depolarization
Ca functions to _______ length of AP and helps with contraction of the heart
prolong
K is important for _________
repolarization
In an _________ ________ ________, it is impossible to fire another AP
absolute refractory period (ARP)
A(n) _________ ________ _________ is unable to have a functionally effective AP
Effective refractory period
Effective refractory period (ERP) lasts the length of _______ and then a tiny bit more
absolute refractory period (ARP)
An effective refractory period (ERP) can fire AP in an indiv. cell but CANT ___________ ____ ______ ____
ripple to next one
The long absolute refractory period (ARP) of cardiac myocytes is vital physiologically because it allows the heart to fill with blood and prevents ________ _________ of cardiac contraction
temporal summation
Relative refractory period (RRP) can get an AP only with a large enough __________
depolarization
Supranormal period (SNP) is from end of ______ to end of ______
relative refractory period (RRP); AP
Period when:
- Easier to fire an AP than rest
- All VG Na channels are back at rest and Vm is depolarized, so don’t need much of a stimulus
Supranormal Period (SNP)
If you fire an AP during RRP or SNP, contraction will be incredibly ________ and not much blood will be ejected.
weak
There is a relationship between the length of APs in cardiac contractile & skeletal m. cells, and the length of __________
contraction/relaxation
Refractory period of cardiac muscle lasts almost the entire legnth of the cardiac muscle twitch. This allows time for _______ _______
cardiac filling
