Cardiac Valves
What 2 structures prevent the AV valves from prolapsing back into the atria after the valves shut?
Chordae Tendinea and Papillary Muscles
Name the 3 major coronary arteries
RCA, LAD, Cx
What does the embryonic heart start as?
2 tubes
What 2 purposes does the heart specialized fibers have?
to form electrical impulses
to conduct those impulses
A normal umbilical cord has ____ arteries and ____ vein.
2 arteries and 1 vein
In an echo exam, how can I expect the TV valve to sit in relation to the MV?
Coronary arterial branch fusing networks are called what kinds of routes?
Collaterals
Once the baby is born, how does the pressure in the atriums change?
increase in LA pressure
decrease in RA pressure
What 3 ions are the principal ions responsible to action potential?
K+
NA+
Ca++
3 types of stimuli
chemical, mechanical, electrical
A prolapsing heart valve causes regurgitation or stenosis?
Regurgitation
What is the estimated oxygen saturation percentage in the coronary sinus?
about 30%
Describe from top to bottom the regions of cardiac tube.
TA (truncus arteriosus)
BC (bulbus cordis)
PV (primitive ventricle)
PA (primitive atrium)
SV (sinus venosus)
Describe each phase of action potential in simple terms.
Phase 0: cell depolarizes
Phase 1: partial repolarization
Phase 2: excitation-contraction coupling
Phase 3: repolarization phase
Phase 4: resting membrane potential
What does the Purkinje fibers supply?
supply the papillary muscles before supplying the lateral wall of the left ventricle
Describe the changes that occur with the following structures at end-systole:
LV cavity:
ICS & PW:
AV:
MV:
IVS & PW: thickest
AV: just closed
MV: closed but about to open
Describe why increased HR can cause ischemia in a patient with coronary artery blockages?
With increased HR comes a shorter diastole, decreasing perfusion time for the coronary arteries.
27 days
What is the difference between the absolute refractory period and the relative refractory period?
Absolute refractory: cell is unresponsive to any stimuli
Relative refractory: cell will respond, but only to higher magnitude stimuli
SA node intrinsic rate:
AV junctional cells:
Purkinje's network cells:
SA: 60-90 impulses/min
AV: 40-60 impulses/min
Purkinje's: <40 impulses/min
What 2 things happen when the mitral and/or aortic valves become too leaky or stenotic?
Increased Cardiac workload
Heart can become week
In order what is the coronary circulation starting with the aorta.
Aorta-> coronary arteries-> capillary beds-> cardiac veins-> coronary sinus-> RA-> RV-> PA-> lungs-> pulmonary veins-> LA-> LV-> back to aorta
What are the 3 main Fetal Shunts and describe one.
Foramen Ovale: flow is directed across the RA by eustachian valve (after birth becomes fossa ovalis)
Ductus Arteriosus: a few weeks after birth-> ligamentum arteriosum
Ductus Venosus: liver shunt; enables oxygenated blood from mom to pass almost directly into fetal heart (bypassing liver), after birth-> ligamentum venosum
What are the 4 basic cells and the 2 groups they are separated in?
Working Cells: contractile cells
Specialized conduction cells: P cells, transitional cells, and Purkinje's cells
Conduction Pathway order
SA node-> internodal pathways-> AV node-> Anulus fibrosus-> Bundle of His/AV bundle-> Bundle branches-> LBB-> RBB-> Purkinje Fibers