Human Heart Circulatory system(Part 1)
An Introduction to the Cardiovascular System
The
cardiovascular
system can
be thought of as the transport system of the body. This system has
three main components: the heart,
the blood
vessels and
the blood itself. The heart is the system’s pump and the blood
vessels are like the delivery routes. Blood can be thought of as a
fluid which contains the oxygen and nutrients the body needs and
carries the wastes which need to be removed. The following
information describes the structure and function of the heart and the
cardiovascular system as a whole.
Structure and Function of the Heart
Function and Location of the Heart
The
heart’s job is to pump blood around the body. The heart is located
in between the two lungs. It lies left of the middle of the chest.
Structure of the Heart
The
heart is a muscle about the size of a fist, and is roughly
cone-shaped. It is about 12cm long, 9cm across the broadest point and
about 6cm thick. The pericardium
is
a fibrous covering which wraps around the whole heart. It holds the
heart in place but allows it to move as it beats. The wall of the
heart itself is made up of a special type of muscle called
cardiac muscles.
Chambers of the Heart
The
heart has two sides, the right side and the left side. The heart has
four chambers. The left and right side each have two chambers, a top
chamber and a bottom chamber. The two top chambers are known as the
left
and right atria (singular:
atrium). The atria receive blood from different sources. The left
atrium receives blood from the lungs and the right atrium receives
blood from the rest of the body. The bottom two chambers are known as
the left and right ventricles. The ventricles
pump
blood out to different parts of the body. The right ventricle pumps
blood to the lungs while the left ventricle pumps out blood to the
rest of the body. The ventricles have much thicker walls than the
atria which allows them to perform more work by pumping out blood to
the whole body.
Blood Vessels
Blood Vessel are tubes which carry blood. Veins are blood vessels which carry blood from the body back to the heart. Arteries are blood vessels which carry blood from the heart to the body. There are also microscopic blood vessels which connect arteries and veins together called capillaries. There are a few main blood vessels which connect to different chambers of the heart. The aorta is the largest artery in our body. The left ventricle pumps blood into the aorta which then carries it to the rest of the body through smaller arteries. The pulmonary trunk is the large artery which the right ventricle pumps into. It splits into pulmonary arteries which take the blood to the lungs. The pulmonary veins take blood from the lungs to the left atrium. All the other veins in our body drain into the inferior vena cava (IVC)or the Superior Vena Cava. These two large veins then take the blood from the rest of the body into the right atrium.
Valves
Valves are fibrous flaps of tissue found between the heart chambers and in the blood vessels. They are rather like gates which prevent blood from flowing in the wrong direction. They are found in a number of places. Valves between the atria and ventricles are known as the right and left atrioventricular valves otherwise known as the tricuspid and mitral valves respectively. Valves between the ventricles and the great arteries are known as the Semilunar valves. The aortic valves is found at the base of the aorta, while the pulmonary valves is found the base of the pulmonary trunk. There are also many valves found in veins throughout the body. However, there are no valves found in any of the other arteries besides the aorta and pulmonary trunk.
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