Question

Mammalian heart is
A)Neurogenic
B)Myogenic
C)Digenic
D)None of the above.

Answer 1

Hint: Mammals show the presence of 4 chambered hearts and play role in double circulation in which oxygenated and deoxygenated blood does not mix up. The SA node is usually located in the right atrium and is termed as the pacemaker. The SA node is necessary for maintaining the heartbeat and pulse rate.

Complete answer:
Heart of mammals is four- chambered and it is present in the thoracic cavity. The SA node is located in the right atrium. It leads to the contraction of the atrium and deoxygenated blood flows from the right atrium to ventricles and from ventricles to the lungs where the blood is oxygenated. Oxygenated blood from the lungs is transferred to the left atrium and then to the left ventricle. From the ventricle, blood is transferred to body parts.

Now let us find solution from given options:

Neurogenic : In contrast with myogenic heart, the neurogenic heart is not under muscular control. The neurogenic heart is under muscular control. The neurogenic heart is observed in
annelids, crustaceans, etc.

Myogenic : Mammals possess a myogenic heart which contracts and relax rhythmically and controls the amount of blood flow. Also, the mammalian heart is four- chambered consisting of two atria and two ventricles. Right atrium shows the presence of a sinoatrial node or SA node which is also termed as the pacemaker of the heart as it produces contraction of the heart and also regulates the heartbeat. The impulse of contraction of the heart starts in the heart by itself, as a result, the mammalian heart is called myogenic.

Digenic : When the heart is regulated by two stimuli, it is termed as digenic heart.

None of the above : As one of the options is correct, this option is not correct.

Hence, the correct answer is option (B)

Note: In myogenic heart, the impulse of contraction is begun by sinoatrial nodes present in the heart itself and in the neurogenic heart, an impulse is started by nerves present in the heart. Hence, the myogenic heart is controlled by muscular control and the neurogenic heart is under neural control.