Question

Assertion :Mammalian heart is called myogenic heart. Reason: Heart-beat is regulated by a specialized muscle bundle (pacemaker) in mammals.

• A. Both (A) and (R) are true and (R) explains (A).
• B. Both (A) and (R) are true but (R) doesnt explain (A)
• C. (A) is true but (R) is false.
• D. (A) is false but (R) is true.

Answer 1

The correct option is A Both (A) and (R) are true and (R) explains (A).

• The heart is the major pumping organ involved in the circulation of the blood. The heart in mammals is known as myogenic heart.
• The functioning of the heart is regulated by the contraction of the muscles.
• The heart beat is regulated by the specialised muscle fibres called as Purkinje fibres.
• These fibres contract and help in the transmission of the impulse. The fibres help to maintain the blood flow by contraction and relaxation.
• This results in the control and regulation of the heart by the muscles. Hence, the heart is called as myogenic.
• Thus, the correct answer is option A.