3.2 Describe the structure of the heart.

The heart is hollow and is said to look like ‘an upside down, pear shape shell’. It consists of three layers the epicardium, this is the thin outer layer that is smooth and has a slippery texture. Myocardium, this is made up of strong cardiac muscle fibers which are connected to the electrical synapse and this is responsible for the pumping action and the endocardium this is the inner lining which contains large blood vessels in which the heart connects to. The inside of the heart is divided into four chambers, the left and right atria and the left and right ventricles, which fills with blood and empties. The two atria’s form part of the top curve and the two ventricles form a base.
The heart is separated into left and right side by the septum. A valve connects each atrium to the ventricle below.
The bicuspid valve connects each atrium to the ventricle and the tricuspid valve connects the right atrium to the right ventricle (http://www.integrativebiology.ox.ac.uk/heartrefs.html).
Blood flows from the right ventricle to the pulmonary artery and to the lungs.
The aortic is between left ventricle and blood flows into the left ventricle to the aorta and to the whole body. Nodes are responsible for the heart beat and control the rhythmic sequence of contractions. They are called sinatrial nodes and artioventricular nodes ventricular.