Human Heart

The heart is one of the critical organs that helps provide oxygen to all parts of the body. Read on to know more about the development and anatomy of the human heart…
Human Heart
The muscular organ that pumps blood through the blood vessels of our body by repeated, rhythmic contractions is the heart. If the average human age is considered to be 66 years then at an average of 72 beats per minutes, the heat beats approximately 2.5 billion times during the lifespan of the individual.

Development of the Heart

Twenty one days after conception the human heart begins to beat at the rate of 70 – 80 beats per minute and accelerates linearly for the first month of beating peaking at 185 beats per minute when the embryo is 7 weeks old. The rate of acceleration is 3.3 beats per day or almost a 100 beats a month.

This accelerated heart rate continues till the embryo is 9 weeks old after which it decelerates to 152 beats per minute and averages down to 145 beats per minute after the 15th week and continues till the baby reaches its term.

Structure of the Heart

In our body, the heart is situated in the middle of the thorax with its largest part slightly offset to the left under the breastbone. The reason as to why we feel that the heart is located on the left side is because the left heart that is the left ventricle is stronger and pumps blood to all parts of the body.

The heart is enclosed in a sac that is known as pericardium and is surrounded by the lungs. The pericardium itself comprises of two parts: a dense fibrous connective issue known as the fibrous pericardium and the serous pericardium which is consists of a double membrane structure which contains a serous fluid to reduce the friction that is produced during the heart contractions.

In normal adults, the mass of the heart is between 250gms – 350gms and is about three quarters the size of a clenched fist. It consists of four chambers, the upper two chambers are the atria (left atrium and right atrium) while the lower two chambers are known as the ventricles (left ventricle and right ventricle).

How the Human Heart Functions

The de-oxygenated blood from the body is poured into the right atrium. The right atrium pumps the blood into the lungs via the right ventricle. The blood is passed into the lungs to remove the carbon dioxide from the blood and add oxygen. This is achieved through the process of passive diffusion. The oxygenated blood accumulates in the left atrium from where it is pumped into the body via the left ventricle.

As the ventricles are responsible for pumping the blood either to the lungs or the body while the atria just collect the blood and pump it to the ventricles, it is quite obvious that the walls of the ventricle will be thicker and stronger than that of the atria. Further, as the left ventricle has to pump the blood to the lungs which is located close by while the right ventricle has to pump blood to the entire body via systemic circulation, the walls of the left ventricle is thicker when compared to right ventricle.

Next, coming to the valves that are present in the heart, blood flows from the right atrium to the right ventricle via the tricuspid valve. From the right ventricle, the blood travels out of the heart via the semi-lunar valve and flows into the lungs through the pulmonary artery. Oxygenated blood enters the left atrium via the pulmonary vein. From here, the mitral valve helps the flow of blood to the left ventricle. Finally, blood is passed to the aorta via the semi-lunar valve which in turn helps the blood travel through the body.

Lastly, the aorta forks and the flow of blood are divided between major arteries. The blood travels from these major arteries into the smaller arterioles and then finally into the tiny capillaries that feed each cell. The deoxygenated blood then travels via the venules which join together to form the veins which further join together to form the superior and inferior venae cavae. This vein brings the blood back into the right atrium where the entire process starts again.

The importance of the heart in the human body cannot be stressed sufficiently. It can easily be stated that this organ helps pump life into the body and proper diet and excerise is the only right way of taking good care of this organ.

By Anju Shandilya
Published: 2/26/2008

Source: www.buzzle.com