Explain the importance of the circulatory system of animals

1) Explain the importance of the circulatory system of animals 2) Describe the types of circulatory system of animals 3) Describe the structure of the heart and blood vessels in animals

1) it performs functions such as transporting oxygen to organs and tissues, communication between cells of the whole organism. Maintains the constancy of the internal environment.
2) circulatory system: closed – blood flows only through the capillaries and vessels, and not closed – blood flows through the vessels directly into the body cavity.
3) When there was the beginning of evolution, the heart was two-chambered, then three-chambered with an incomplete septum, first mixed blood was carried, and then a four-chambered one appears.