the series of physical events that transports blood through all four heart chambers during one heartbeat
first heart sound
heart sound that is produced by closure of the atrioventricular valves and that signals the beginning of systole; characterized as "lub" and usually loudest over the apex area of the heart
second heart sound
heart sound produced by closure of the semilunar valves; signals the ending of systole
third heart sound
ventricular filling sound. Occurs in early diastole during the rapid filling phase. Dull soft sound. Low pitched like distant thunder. Heard best at the apex w/ the bell held lightly w/ the person in the L lateral position. S3 is usually abnormal. Pathologic S3 is called ventricular gallop.
end diastolic volume
the amount of blood in each ventricle at the end of its relaxation period, about 130 mL
occurs b/w av valve closure and semilunar valve open; all 4 valves are closed momentarily; pressure gradient forces semilunar valves to open
Semilunar valves are open, blood is pushed from ventricles into aorta & pulmonary trunk
measurement of the volume percentage of left ventricular contents ejected with each contraction
end systolic volume
the amount of blood remaining in each ventricle at the end of ventricular contraction, about 60 mL
a brief interval during ventricular diastole when ventricular blood volume does not change because all four valves are closed
Autonomic response to changes in blood chemistry, especially pH and concentrations of O2 and CO2. Initiated by chemoreceptors aortic bodies and carotid bodies. Adjust respiration to changes in blood chemistry. Also stimulates vasomotion. Hypoxemia, hypercapnia & acidosis induce vasoconstriction to increase LUNG perfusion!
Autonomic negative feedback response to changes in blood pressure, detected by carotid sinuses. Input inhibits sympathetic cardiac and vasomotor neurons, reduces sympathetic tone, excites vagal fibers to the heart. Reduces heart rate and cardiac output, dilates arteries and veins and reduces blood pressure.
frank starling law of heart
this states that the greater the preload on cardiac muscle fibers before contraction, the stronger the force of contraction