The human circulatory system—also known as the cardiovascular system—is responsible for transporting blood, nutrients, oxygen, carbon dioxide, hormones, and other essential substances throughout the body. It is crucial for maintaining homeostasis and supporting all cellular functions.

Main Components of the Circulatory System:

Heart

A muscular organ that pumps blood throughout the body.

It has four chambers: right atrium, right ventricle, left atrium, and left ventricle.

Blood Vessels

Arteries: Carry oxygenated blood away from the heart to the body (except pulmonary arteries).

Veins: Carry deoxygenated blood back to the heart (except pulmonary veins).

Capillaries: Tiny vessels where exchange of gases, nutrients, and wastes occurs between blood and tissues.

Blood

Composed of red blood cells, white blood cells, platelets, and plasma.

Transports oxygen, nutrients, and hormones; removes waste products.

Functions of the Circulatory System:

1. Transportation

Delivers oxygen from the lungs to tissues.

Transports nutrients from the digestive tract to cells.

Carries hormones from glands to target organs.

Removes waste products (like CO₂ and urea) for excretion.

2. Regulation

Helps maintain body temperature (thermoregulation).

Balances pH levels and water content in the body.

3. Protection

Circulates white blood cells and antibodies to fight infections.

Platelets and clotting factors help in wound healing and prevent blood loss.