Human Cardiovascular System: Anatomy and Function

General Function

The cardiovascular system transports various substances to and from cells.

Heart Anatomy and Function

The heart is a hollow, muscular organ responsible for pumping blood throughout the cardiovascular system to maintain adequate pressure. It is situated in the thoracic cavity.

Heart Structure

• Dimensions: Conical shape, weighs approximately 250g, and measures 10cm in length.
• Chambers: Composed of four chambers: two upper atria (right and left) and two lower ventricles (right and left).
• Septa: The atria are separated by the interatrial septum, while the ventricles are separated by the interventricular septum.

Valves and Blood Flow

The right atrium communicates with the right ventricle via the tricuspid valve. The left atrium communicates with the left ventricle via the mitral valve. These valves prevent the backflow of blood from the ventricles to the atria. Ventricular walls are thicker than atrial walls to withstand the pressure required to pump blood.

Blood Vessels

• Arteries: Carry blood away from the heart; they are highly elastic.
• Veins: Carry blood toward the heart; they are less elastic and contain valves to prevent backflow.
• Capillaries: Extremely fine vessels that reach all tissues to deliver nutrients and remove waste products.

Circulatory Circuits

Pulmonary Circuit

Starts from the right ventricle, travels through the pulmonary artery to the lungs for gas exchange (oxygen and carbon dioxide), and returns to the left atrium.

Systemic Circuit

Starts from the left ventricle and pumps oxygenated blood through the aorta to the rest of the body.

Cardiac Physiology

Cardiac Frequency

Refers to the number of pulsations per minute.

Cardiac Cycle

The sequence of mechanical, chemical, electrical, and sound phenomena that occur in the heart, beginning with atrial systole (contraction) and ending with the subsequent atrial contraction.

Blood Pressure

The force exerted by blood against the walls of the blood vessels. It is essential for ensuring blood reaches all body tissues.