Cardio 3 Flashcards
tachycardia
fast >70/72 bpm
bradycardia
slow <70/72 bpm
What is the heart rate?
P to P or R to R
arrhythmia
abnormal rhythm; can appear as longated segments or intervals, altered, missing or additional waves.
premature ventricular contractions
-purkinje fibres kick in as pacemaker due to insufficient oxygen to myocardium; perceived as skipped beat or palpitation
long QT syndrome
- inherited
- delayed repolarization of ventricles
cardiac cycle
one complete contraction and relaxation
diastole
when cardiac muscle relaxes
systole
when cardiac muscle contracts
5 phases of a single cardiac cycle
-The heart at rest: atrial and ventricular diastole (late diastole)
-completion of ventricular filling (atrial systole)
-Early ventricular contraction (isovolumetric ventricular contraction)
-The heart pumps (ventricular ejection)
-Ventricular relaxation (isovolumetric ventricular relaxation, early
diastole)
late diastole
both sets of chambers are relaxed and ventricles fill passively
atrial systole
atrial contraction forces a small amount of additional blood into ventricles
isovolumetric ventricular contraction
first phase of ventricular contraction pushes AV value closed, but does not create enough pressure to open semilunar valves - LUB
ventricular ejection
as ventricular pressure rises and exceeds pressure in arteries, the semilunar valves open and blood is ejected
isovolumetric ventricular relaxation
-as ventricles relax; pressure in ventricle falls, blood falls back into cusps of semilunar valves and snaps them close
EDV
end diastolic volume; maximal amount of blood in the ventricles after filling; ~ 135mL
ESV
the volume of blood left over after contraction; ~65mL
A-A’ segment of pressure volume loop
starts at ESV
-(late diastole) pressure in ventricle is lower than atria and the AV valve opens causing the ventricle to passively fill with blood
A’-B segment of pressure volume loop
- (atrial systole) atria contracts forcing more blood into the ventricle slightly increasing volume and pressure
- EDV
B-C segment of pressure volume loop
(isovolumetric contraction) the ventricle begins contracting closing AV valve, continued contraction causes a large increase in pressure within the ventricle
C-D segment of pressure volume loop
(ventricular ejection) Once pressure in ventricle rises above ~80mm Hg, it exceeds the aorta and the aortic valve opens causing a rapid ejection of blood
D-A segment
isovolumetric relaxation; pressure in aorta begins to exceed ventricle causing semi-lunar valve to close, ventricle continues to relax
D - Wiggers Diagram
ventricle relaxes, pressure in atria begins to exceed ventricle -AV valve opens and you get the passive filling of the ventricle
-Atria then contracts increasing the volume and pressure slightly
C - wiggers diagram
ventricle beings to contract, increasing pressure within ventricle causing the AV valves to snap shut (LUB)
