Assertion Reason Test: Body Fluids & Circulation - NEET MCQ

A: Portal system consists of veins which start from capillaries and end into capillaries.

R: All vertebrates have hepatic portal systems.

A: Left ventricle pumps blood at a much higher pressure to all body parts involved in the systemic circulation.

R: The muscular wall of left ventricle is two to four times as thick as the wall of the right ventricle.

A: The resting heart rate, about 75/minutes, usually is lower than the autorhythmic rate of the SA node (90 – 100 beats/minute).

R: At rest condition, the parasympathetic effects dominate.

A: Elevated levels of Na+ increases the heart rate and contractility.

R: Elevated Na+ level increases the excitability of SA nodes.

A: Endocardium provides a smooth lining for the inside of the heart and covers the valves of the heart.

R: Endocardium is continuous with the endothelial lining of the large blood vessels associated with the heart and the rest of the cardiovascular system.

A: Isovolumetric systole of a normal cardiac cycle is responsible for opening semilunar valves, causing the blood flow into aortic aorta and pulmonary aorta.

R: During isovolumetric systole, intraventricular pressure increases as semilunar and AV valves are closed, and ventricles are contracting.