Question

Contraction of heart is called as
(a) Peristalsis
(b) Systole
(c) Diastole
(d) Voluntary contraction

Answer 1

Hint: It involves the sequence contraction of the atria and ventricles (chambers of the heart). The contraction takes about 0.1 seconds for atria and 0.3 seconds for ventricles. It happens after the contraction of the atria and is a part of the cardiac (relating to the heart) cycle.

Complete answer:
The alternate contraction of the heart is called systole.
The cardiac cycle has three phases:
1. Atrial systole: It involves the contraction of atria from the anterior to the posterior side which pushes blood to the respective ventricle. It increases the blood flow of the ventricle by 30 percent. It is also called a mid-late diastole. There is no reflux of blood from the auricles to the large veins. The atrial diastole (relaxation) takes about 0.7 seconds.
2. Ventricular systole: It involves the simultaneous relaxation of the atria and contraction of the ventricles. The ventricular diastole (relaxation) takes about 0.5 seconds.
3. Joint diastole: All the chambers during this phase are in a relaxed phase. During complete diastole, blood from the great vein flows into the atria.
So, the correct answer is, ‘Systole.’

Additional Information: Lub or systolic sound is the first heart sound. It is heard at the beginning of the ventricular systole and is due to the rapid closing of the atrioventricular (between atria and ventricles) valve.

Note: The heart has four chambers, the upper two chambers are called the auricles and the lower two chambers are called the ventricles. All the chambers do not beat simultaneously. Right and left auricles to contract simultaneously while right and left ventricles contract after the contraction of auricles has ended. The auricles relax while the ventricles contract.