Human Circulatory System

1. heart

1.1. heartbeat

1.1.1. A cycle of contraction and relaxation of the heart muscles

1.1.2. rate of our heartbeat

1.2. receives oxygen-rich blood from the lungs and pumps it to the cells of the body

2. two important functions

2.1. transports oxygen, digested food and water to all parts of the body

2.2. transports carbon dioxide and waste materials away from different parts of the body to be released.