Body Fluids And Circulation

The two atria are separated from the ventricles by membranous valves. The valve separating the right auricle from the right ventricle is known as the right atrioventricular valve or tricuspid valve (as it is made of three flaps or cusps). The valve separating the left atrium and the left ventricle is called left atrioventricular valve or the bicuspid valve or the mitral valve (since it is made of two flaps).

A protein named rhesus antigen is present on the surface of red blood corpuscles in many persons. It was discovered in 1940 by Landsteiner and Wiener in the blood of Rhesus monkey, Macaca rhesus hence its name. Depending on the race, 85 to 99 percent of the white population have this rhesus antigen (also called Rh fatcor) and are called Rh positive (Rh). Others who do not have this factor are known as Rh negative (Rh). Rh is dominant to Rh.

Two sounds are heard normally through a stethoscope during each cardiac cycle. The first is a low, slightly prolonged "lubb" (first sound), caused by sudden closure of the. mitral and the tricuspid valves (atrioventricular valves) at the? start of ventricular? systole. The second is a shorter, high pitched "dupp" (second sound) caused by. vibrations associated with closure of the aortic and pulmonary valves just after the end of the ventricular systole.The first sound has a duration of 0.15 second and a frequency of 25-45 Hz. The second sound lasts about 0.12 seconds with a frequency of 50 Hz.

Cardiac output or heart output is the amount of blood pumped by heart (or more precisely by one ventricle either right or left) per minute. Cardiac output can be calculated as:
Heart rate ? Stroke volume (i.e.,the volume of blood ejected by one ventricle during each beat).
Heart of a normal person beats 72 times per minute and pumps out about 70 ml of blood per beat and about 5 litres per minute which? is equivalent to the total? body blood volume (about 5.5 litres).