Obesity and the Cardiovascular System
The main function of the cardiovascular/circulatory system is to
continuously pump blood around the body. It consists of the heart,
arteries, veins and the capillary network of arterioles and venules.
The capillary network is vast consisting of 62,000 miles of blood
vessels. Any blockages in cardiovascular system can be very dangerous
to our health, even fatal.
The heart, the body's pump, has 2 compartments separated by a septum.
Each compartment contains 2 chambers, atrium and ventricle. The right
side pumps de-oxygenated blood to the lungs (pulmonary circulation)
and left side oxygenated blood to all other organs and tissues
The heart is made up of a special kind of muscle - myogenic/cardiac
muscle which contract automatically and rhythmically.
The diagram below shows compartments of the heart in more detail.
Heart, Section Through the Middle
Blood used by the body returns through the veins to the right
compartment (pulmonary circulation) of the heart via the inferior and
superior cava, (these are large veins). This blood is then pumped by
the heart to the lungs, where carbon dioxide is removed and blood is
oxygenated. This blood is then returned back to the left compartment
of the heart via 4 pulmonary veins, where it will be pumped to all
other cells in the body including the heart itself. The left side of
the heart has a thicker more muscular wall because it has to pump
blood much further, around the entire body.
The movement of blood through the heart is governed by its
sophisticated structure. Between the atrium and ventricle on both
sides of the heart there are atrioventricular valves, (Tricuspid &
Mitral) these are cup shaped, which allow blood to flow from atrium to
ventricle but do not allow backflow.
The atrioventricular valves are pushed open when blood enters
ventricles from atrium. When ventricles contract these valves are
forced shut by the pressure of blood in the ventricle and outlet
valves, pulmonary and aortic valves open, forcing blood out to the
lungs and body. When ventricles relax the opposite occurs.
There is one artery on either side of the heart, the pulmonary on the
right and the aorta on the left. These are the vessels that carry
blood away from the heart. Blood leaves the left ventricle (systemic
circulation) through the aortic artery (arteries carry blood at high
pressure so artery walls have to be thick, strong and elastic) which
divides into progressively smaller branches to the smallest of the
arteries, arterioles. The arterioles branch into a vast number of tiny
capillaries. Capillaries deliver food and oxygen direct to the body
tissues and take away waste products, which is why capillaries are
only one cell thick to allow substances to diffuse...