Three layers of tissue form the heart wall. The outer layer of the heart wall is the epicardium, the middle layer is the myocardium, and the inner layer is the endocardium.
On each side of the wall, there is a small collecting chamber called an ‘atrium’, which leads into a large pumping chamber called a ‘ventricle’. There are four chambers: the left atrium and right atrium (upper chambers), and the left ventricle and right ventricle (lower chambers).
Your heart is the only circulatory system organ.
Three layers of tissue form the heart wall. The outer layer of the heart wall is the epicardium, the middle layer is the myocardium, and the inner layer is the endocardium.
On each side of the wall, there is a small collecting chamber called an ‘atrium’, which leads into a large pumping chamber called a ‘ventricle’. There are four chambers: the left atrium and right atrium (upper chambers), and the left ventricle and right ventricle (lower chambers).