cardiac cycle Flashcards
what is the blood pressure in vessels with no flow
7 mmHg
how is the heart orientated
right side is mostly anterior
what are the 5 stages of the cardiac cycle
- atrial systole
- isovolumetric contraction
- ventricular ejection
- isovolumetric relaxation
- ventricular filling
what does the;
P
QRS
T
waves stand for in ECG
- p is atrial depolarisation followed by contraction
- QRS is ventricle depolarisation followed by contraction
-T is ventricle repolarisation- isovolumetric relaxation of cardiac cycle
wiggers diagram what side of the heart does it measure
left
during what stages of the cardiac cycle are all valves closed
- isovolumetric contraction
- isovolumetric relaxation
during what stage of the cardiac cycle is ventricular volume the highest
- very end of atrial systole/ isovolumetric contraction
during what stage of the cardiac cycle is the ventricular volume the lowest
- very end of ventricular ejection
- isovolumetric relaxation
during what stage is ventricle pressure the highest
- middle of ventricular ejection
when does av valves open
when atrial pressure is greater than ventricular pressure
when does semi lunar valves open
- when ventricular pressure is greater than aortic pressure
when do av valves close
when ventricular pressure greater than atrial pressure
when do semi lunar vlaves close
when aortic pressure> ventricular pressure
what is the diastollic pressure
- lowest pressure - when heart relaxes
what is sytollic pressure
- pressure generated by left ventricle, so when its contracting
what is mean arteriole pressure
MAP= 1/3(SP-DP)+DP
what is stroke volume
change in volume of the ventricle when its contracting and ejecting blood out int the aorta during ventricular ejection in one cardiac cycle
stroke volume equation
end diastolic volume- end systolic volume
what increases cardiac output
increased heart rate
what is pre load
the amount of blood than enters the left ventricle
what affects stroke volume
- increased pre load= increase stroke volume
- increased contractility= increased stroke volume
- increased after load decreases stroke volume
why does an increased pre load increases stroke volume
- increased pre load means the ventricles are more stretched
- this causes the cardiac muscle fibres to lengthen and this consequently increases stroke volume and the amount of blood that is ejected
why does an increased after load decreases stroke volume
- increased after load means the heart has to build up more pressure to eject blood out and therefore work harder resulting in a lower stroke volume
what is the starling law
- increased pre load results in ventricle stretch which leads to cardiac muscle fibres to lengthen and therefore this increases stroke volume
- graph is stroke volume against pre load and has a plaeteau shape graph where at high preloads stroke volume does not increase
what is the lub dub sound that we can heart when listening to the heart
- first sound is lub and is the closing of the av
- second sound is dub and is the closing of the semi lunar valves
what are the two valvular pathology
- stenosis
- regurgitation
what is stenosis and what impact does it have on the wiggers diagram
- stenosis= valves cannot open
- aortic stenosis, semi lunar valve does not open and therefroe on the wiggle diagram theres a massive increase in ventricular pressure (greater pressure gradient between left ventricle and aortic pressure), also murmers in systole
- mitral stenosis- increased atrial pressure, ,murmers in diastole
what is regurgitation and what impact does it have on wiggers diagram
- regurgitation valves do not close properly
- aortic regurgitation results in decreased diastolic aortic pressure as blood flows back into the lf- murmers in diastole
- mitral regurgiation- increase in left atrial pressure as blood flows back into left atrial from ventricle during systole- so murmer during systole
