CARDIO Flashcards
Stroke volume
volume of blood ejected per beat
cardiac output
the amount of blood pumped out of the left ventricle per minute
(stroke volume x heart rate
heart rate
number of times heart beats in a minute
end diastolic volume (EDV)
volume of blood in the ventricles at the end of diastole
end systolic volume (ESV)
volume of blood in the ventricles at the end of systole
ejection fraction
proportion of the end diastolic volume that is pumped out of the left ventricle per beat
stroke volume/EDV provides an indication of the contractility of the heart
“Lub”
first heart sound (S1)
closing of the atrioventricular valves
“Dub”
second heart sound (S2)
closing of the semilunar valves
what occurs during the P wave (in relation to cardiac cycle)?
the SAN is depolarised and the ventricles relax and the mitral valves open.
what happens immediately after the p wave?
the atria contract. the left atrium empties into the left ventricle and the pressure of the left atrium decreases.
although the left ventricle fills with blood, it dilates so the pressure is lower than that in the left atrium - this prevents the backflow of blood
what happens during the QRS complex?
blood fills the left ventricle and the mitral valve closes as the left ventricle fills. the aortic valve is also closed. isovolumic contraction begins and creates a pressure of 120mmHG.
This contraction allows the aortic valve to open as pressure here is lower than the left ventricular pressure. due to this, blood is ejected into the aorta at high speed.
at what point do we say isovolumic contraction has finished?
as soon as ejection occurs because the volume of blood in the left ventricle has changed
what happens during the T wave?
the ventricles are still contracting. however, the ejection starts to decrease and there is a fall in pressure.
ATP hydrolysis breaks the bond of Ca++ and TnC and the muscles relax
Pressure in the ventricle drops to 80mmHG and the aortic valve closes
25% of volume is still left in the left ventricle and pressure continues to decrease
this is called isovolumic relaxation and gos down to 0mmHg
when does the first heart sound occur?
during ventricular contraction. specifically when the mitral valve closes
when does the second heart sound occur?
during ventricular relaxation. when the aortic valve closes
how long is systole?
0.3 milliseconds
how long is diastole?
0.5 ms
What is the journey of blood through the heart?
blood that is deoxygenated comes from the tissues and enters the right atrium
it then passes through the tricuspid valve into the right atrium
the blood in the right ventricle then passes through the pulmonary valve and enters the lungs
the pulmonary veins drain blood from the lungs into the left atrium
this oxygenated blood then passes through the mitral valve into the left ventricle
this blood is then ejected out to through the aortic valve into the aorta where it goes to the tissues
what forms the thoracic cage?
sternum attached to clavicles
what are the three parts of the sternum?
manubrium
body
xiphoid process
where is the manubrium located?
between T2-4
what is found at the T4/5 level?
- demarcates the superior and inferior mediastinum
- bifurcation of trachea
- bifurcation of pulmonary trunk
- start and end of arch of aorta
- formation of superior vena cava
- azygos vein joining superior vena cava
- thoracic duct crosses it
where is the sternal angle?
adjacent to T4/5 level
what are the parts of the mediastinum?
superior mediastinum
anterior mediastinum
middle mediastinum
posterior mediastinum
