Human Heart

When the auricles relax, the tricuspid and bicuspid valves shut, which creates the first heart sound called lubb.

This is the normal systolic blood pressure of an adult man. The maximum normal B.P. should not exceed 150 mm Hg in adult males.

Sphygmomanometer is used to measure blood pressure. It measures both systolic and diastolic pressures.

It is the graphic record of the electrical variations produced by the beating of heart. It is formed by a series of ridges and furrows.

All the given options cause low blood pressure.

The basic function of pulmonary artery is to carry deoxygenated blood from the heart’s right ventricle into the lungs.

Various valves present at the inlet and outlet of ventricles regulate the flow of blood in heart. Action of these valves creates the heart sounds.

It prevents the artery from collapsing. It is the middle thick coat of circularly disposed, smooth or unstriped muscle fibres and elastic connective fibres. The thick coat prevents arteries from collapsing.

Acetylcholine is a neurohormone which is secreted by neurons of parasympathetic nerves and lowers the heart rate.

The cardio-accelerator which accelerates the heartbeat is connected to the heart through sympathetic nerve fibres.

Leakage of blood through the valves produces murmur sound.

The difference in systolic and diastolic pressure is called pulse pressure.

Wall of tunica interna is made of endothelial cells.

This layer carries small vessels and nerves to nourish the arterial wall.

Arterioles are the smallest tubes of the arterial system.