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| Heart |
| Arterial
Circulation |
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 Inbound
the LHS ventricle, during ventricular systole, pressure increase
very quickly first, while remaining inferior to the aortic pressure;
it is the ohase of isovolumetric contraction, during which valves
remain closed. Aortic valve opens as soon as ventricular pressure
passes over the aortic pressure (approx. 70 mmHg); it reaches
a maximum of about 130mmHg. Ejection is firstly very fast, then
slows down; About 75 ml of blood are sent out of the heart.
Then remains a post-systolic remain of about 105 ml. During
the next phase (isovolumetric relaxation), prior to the opening
of the auriculo-ventricular valve (mitral), ventricle neither
ejects nor receives any blood. Pressure lowers then very quickly.
The aortic blood tens to flow back and hence closes the sigmoid
valves, it is the beginning of the diastole. Filling of the
ventricle starts as soon as the pressure inside the ventricle
reaches the same value as the auricular pressure, which enables
the opening of the mitral valve. The flow quickly accelerate
under the effect of ventricular elasticity, then slows down.
When the atrial systole occurs, the ventricle receives a new
amount of blood, and the pressure slightly increases. By the
end of the atrial systole, ventricular pressure is slightly
superior to the auricular pressure and closes the mitral valve.
(d'après Text Book of Medical Physiology)
Inbound the LHS atrial, pressures are lower, due to the indirect
effect of the ventricular pressures. During its filling, the
maximal pressure slightly passes iver 8mmHg, and decreases as
soon as the mitral valve opens. Inside the RHS cavities, variations
are alike, but pressures are reduced. Sigmoid valves open when
ventricular pressure passes the diastolic pressure of the pulmonary
artery. In side the RHS auricle, maximal pressure is of 6mmHg. |
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