The heart and the vascular system

The heart is an inner hollow muscular organ placed within the chest and included in the pericardium. The base of the heart is against the third rib. Its apex is against the interspace between the fifth and sixth costal cartilages. The weight of the heart is about 300 grams in the mail and about 220 gr in the female.

The heart consists of 2 separate chambers divided by the septum. Each of chambers has 2 connected parts: the atrium and the ventricle.

At the entrance and exit of each ventricle the valves are located. The atrioventricular valves separate the atria from the ventricles.

In the left chamber the atrium and ventricle are separated by the mitral valve.

In the right chamber the atrium and ventricle are separated by the tricuspid valve.

At the point of origin of the aorta in the left ventricle another valve is located. This valve is called the semilunar valve of the aorta.

At the point of origin of the pulmonary artery in the right ventricle the fourth valve is located. It’s called the semilunar valve of the pulmonary artery.

The vascular system consists of 3 groups of vessels – arteries, veins and capillaries.

The vessels carrying blood to and from the tissues of the body compose the general system. They are called the systemic vessels.

The pulmonary system is formed by the vessels carrying blood to and from the lungs.

The portal system is formed by the veins passing to the liver.

The arteries dilate and contract simultaneously with the action of the heart.

Work of the human heart

The human heart contracts from the first moment of life until the last one. Te contractions of the heart pump the blood through the arteries to all the parts of the body. The total weight of the blood pumped by the heart daily I about 10 tons.

In the adult the heart makes from 60 to 72 beats per minute. In children the rate of heartbeat is much higher. The rate of heartbeat increases depending on different emotions.

Each beat of the heart is followed by a period of rest for cardiac muscle. Each wave of contraction and a period of rest following it compose a cardiac cycle.

The heart muscle works or contracts about one 1/3 of the human life. The period of rest is shorter during greater physical exertion and longer when the body is at rest.

Each cardiac cycle consists of 3 phases: the atrial systole, the ventricular systole and the diastole.

The role of the ventricles is the main pump, the atria act as receiving chambers.

The heart sounds

When we listen to the heart we can hear 2 sounds. The third sound is also heard in some persons.

The first heart sound is the longest one. It’s heard at the moment of contraction of the ventricles when the atrioventricular valves close. Also the first sound is heard over all portions of the heart and often over the large vessels. The fisrt sound is greater over the surface of the mitral and tricuspid valves. Normally the first heart sound is heard best over the apex of the heart in the fifth costal interspace.

The second sound lasts for a shorter period of time. It’s heard at the moment when the pulmonary and aortic semilunar valves close. The second sound is heard loudest over the aorta and the pulmonary artery, in the second left and right costal interspaces.

The third heart sound is heard when the blood is passing from the atria into the ventricles.

The heart sounds are very important in the clinical diagnosis and the doctors determine many cardiac diseases by heart sounds.