Download CARDIOVASCULAR SYSTEM PHYSIOLOGY AND MANIFISTATIONS

Lecture I Continued
Introduction; The
Cardiovascular System (CVS)
Dr. Aya M. Serry
2016
Cardiac valves and their functions
The human heart contains four valves:
Two Atrioventricular valves (AV valves) between
the atria and the ventricles:
1. Tricuspid valve between the right atrium and the
right ventricle.
2. Mitral valve between the left atrium and the left
ventricle.
Cardiac valves and their functions
The human heart contains four valves:
Two Atrioventricular valves (AV valves) between
the atria and the ventricles:
1. Tricuspid valve between the right atrium and the
right ventricle.
2. Mitral valve between the left atrium and the left
ventricle.
Cardiac valves and their functions
Two semilunar valves:
1.
2.
Aortic valve between the left ventricle and
the aorta.
Pulmonary valve between the right ventricle
and the
pulmonary artery.
Functions of the cardiac valves
The cardiac valves allow the blood to pass only in one
direction
The AV valves :
Allow for the blood to pass from the atria into the
ventricles during ventricular diastole. During
ventricular systole, the AV valves close to prevent
back flow of blood from the ventricles into the atria.
Functions of the cardiac valves
The semilunar valves:
Allow for the blood to pass from the ventricles into
the arteries during ventricular systole. During
ventricular diastole, these valves prevent back flow of
blood from the arteries into the ventricles (as these
valves become closed during ventricular diastole).
Preload Vs. Afterload
Preload
•
The preload represents the volume work of the heart. It is usually
considered the end-diastolic pressure when the ventricle has
been filled.
•
It is called the preload because it is the work or load imposed on
the heart before the contraction begins.
•
Preload represents the amount of blood that the heart must pump
with each beat, It is largely determined by the venous return to the
heart and the accompanying stretch of the cardiac muscle fibers.
Preload Vs. Afterload
Afterload
•
The afterload is the pressure in which the muscle exerts its
contractile force in order to move blood into the aorta.
•
It is called the afterload because it is the work presented to the
heart after the contraction.
•
The systemic arterial blood pressure is the main source of afterload
work on the left heart, and the pulmonary arterial pressure is the
main source of afterload work on the right heart.
•
The afterload work of the left ventricle is also increased with
narrowing (i.e., stenosis) of the aortic valve.
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