Question

A frog's heart, when taken out of its body, continues to beat for sometime.

Select the best option from the following statements.

(a) Frog is a poikilotherm.
(b) Frog does not have any coronary circulation.
(c) Heart is "myogenic" in nature.
(d) Heart is autoexcitable.

• A. Only (c)
• B. Only (d)
• C. (a) and (b)
• D. (c) and (d)

Answer 1

The correct option is D (c) and (d)

Frog’s heart is myogenic (myo’ is ‘muscle’, and ‘genic’ is ‘originating from’) and auto excitable as the impulse for contraction of heart generates from specialized cardiac muscles present within the heart. The myogenic hearts have an intrinsic contractile property that is independent of the nervous system.

As specialized muscles in the heart initiate impulse for its contraction, it continues to beat even after taking it out of the body for some time.

Hence, the statements (c) and (d) explain the reason as to why the frog’s heart continues to beat for some time after being taken out of the body.

Coronary circulation supplies blood to the tissues of the heart. Frog does have coronary blood vessels.

The poikilotherms cannot maintain a constant body temperature, and it changes as per the surrounding environment. Hence, rising temperature leads to an increase in heart rate.