
Normal activities of the heart are regulated intrinsically, i.e., auto regulated by specialised muscles (nodal tissue), hence the heart is called myogenic. Read following statement and choose correct option for right statements?
(i) Mass of this tissue is seen in the lower left corner of the right atrium close to the atrio- ventricular septum called the sino-atrial node (SAN).
(ii) A bundle of nodal fibres, atrioventricular bundle (AV bundle) continues from the AVN which passes through the atrio ventricular septum is known as bundle of His.
(iii) Bundle of His immediately divides into a right and left bundle which form Purkinje fibres.
(iv) The nodal musculature has the ability to generate action potentials without any external stimuli, i.e., it is autoexcitable.
(v) The SAN can generate the maximum number of action potentials, i.e., 90-95 min.
(vi) Our heart normally beats 70-75 times in a minute (average 72 beats min).

Important Questions on Body Fluids and Circulation
Give the location of the following valve within the human heart.
Bicuspid valve

Give the location of the following valve within the human heart.
Thebesian valve

Give the location of the following valve within the human heart.
Tricuspid valve

Column A | Column B |
P. Neurogenic heart. | i. Human |
Q. Bronchial heart. | ii. King crab |
R. Pulmonary heart. | iii. Shark |

Statement (S): The sinoatrial node is called 'Pace-maker'.
Reason (R): The sinoatrial node contains specialised cardiomyocytes and generates action potentials without any external stimuli.
The correct answer is


Give the location of the following valve within the human heart.
Eustachian valve.



Reason (R): In the heart of the human embryo, oxygenated and deoxygenated blood is completely separated.








Match the following related to the cardiac cycle.
Column I | Column II | ||
Cardiac Cycle | |||
Atrial Systole | |||
Ventricular Systole | |||
Cardiac Diastole | |||

Assertion : Dub' is one of the sounds of the heart caused during a cardiac cycle.
Reason : The sound is due to closure of semilunar valves present at the bases of aortic arches.


