Anatomy

The cardio vascular system is made up of your heart, blood and a vast network of arteries, veins, and capillaries, which help to deliver blood and nutrients to your working muscles, organs and cells, whilst removing carbon dioxide and waste products.

Arteries carry oxygen rich blood away from your heart, and veins carry oxygen poor blood back to your heart. Its is clear to see when you look at your arm, blue veins which are transporting oxygen poor blood back to the heart, so that it can be pumped in to the pulmonary system (lungs) in order to be rejuvenated back into oxygen rich blood.

In pulmonary circulation, though, the roles are switched. It is the pulmonary artery that brings oxygen-poor blood into your lungs and the pulmonary vein that brings oxygen-rich blood back to your heart.

The heart is a muscular pump, about the size of your fist which lies beneath the sternum (chest plate), and is divided into four main parts (chambers), the left and right atrium 4 - 8, upper parts and the lower left and right ventricles 5 - 6.

The left hand side of the heart is responsible for receiving oxygenated blood from the lungs, via the Pulmonary Vein 3, into the left Atrium 4, which is then pumped into the left Ventricle 5, prior to being pumped around the body via the Aorta 1.

The right hand side is responsible for receiving deoxygenated blood from the Superior Vena Cava 9, and also Inferior Vena Cava 7, which passes through the right Atrium 8, into the right Ventricle 6, where it is then pumped into the pulmonary system (lungs) via the Pulmonary Artery 2.

There are a number of non - return valves which separate the upper and lower chambers, and also prevent the back flow of blood.

Blood Vessels

There are three types of vessels that are responsible for transporting blood to and from the heart.

Arteries
Muscular tubes with thick walls, which contract to squeeze blood throughout the body, away from the heart. The arterial wall will stretch to receive the blood under pressure, and then contract to assist blood flow, as there are no valves in order to prevent back flow.

Veins
Thinner walled tubes, which carry blood from tissues back to the heart. All veins have a series of one way valves which work against gravity to prevent back flow of blood as it passes towards the heart.

Capillaries
A mass network of blood vessels whereby the arteries terminate and the veins originate, it is here that nutrients and oxygen passes through the walls from the blood into the individual cells, and likewise where waste products are taken away to be ex created.

Blood

Blood consists of red and white blood cells and platelets, contained in a a liquid medium called plasma.