The circulatory system performs the following functions :

(a) Transportation of gases : The gases like oxygen, carbon dioxide are transported from respiratory organs to every cell in the body. The oxygen is carried from lungs to body cells via heart and carbon dioxide from body cells to lungs.

(b) Transportation of nutrients : The different types of nutrients are transported to different cells.

(c) Transportation of waste products : The waste products like urea, uric acid, ammonia etc. are collected from different body tissues and poured into excretory organs.

(d) Transportation of water : Water and chemical substances are transported all over the body uniformly by blood.

(e) Transportation of hormones : The hormones secreted by the different endocrine glands are carried to their site of targets by blood.