The two sounds heard through the stethoscope during a heartbeat are known as lub and dub. If the doctor detects an unusual lub sound, evaluate which description could explain the atypical sound.

the description that could explain the atypical sound is known as HEART MURMURS.

Explanation:

The doctor makes use of instruments like the stethoscope to listen to the sounds of the heart while examining a patient. The sound heard in a normal heart beat is described as a "lub" and a "dub" sound.

The "lub" sound, which is called the first heart sound, is associated with closure of the atrioventricular valves at the beginning of a systole and the "dub" sound,which is called the second heart sound, is associated with the closure of the semilunar ( aortic and pulmonary) valves at the end of systole.

HEART MURMURS usually occurs when there are abnormalities of the valves which may occur due to congenital heart defects. It is classified according to when it occurs and these includes:

--> systole murmurs: these occurs during the first heart sound and,

--> Diastole murmurs: these occurs during the second heart sound.

Therefore the description that could explain the atypical sound is known as HEART MURMURS

b.) the mitral valve does not close after the systolic phase.

i think the answer would d