Describe the structure of the human heart with the help of a diagram. Also write a note on heart beat.

Human heart is a muscular organ situated in the centre of the thoracic cavity with its lower end tilted towards left. It consists of four chambers -  two auricles which receive blood and
two ventricles which pump blood to different parts of the body. 

Heart beat: The heart beats is a rhythmic pulsation of the heart, including one complete  systole and diastole. The heart beat occurs due to contraction and relaxation of its atrium and ventricles at an average rate of 72 times per minute.


Cross-section of human heart