the heart Essay

The heart

Intro:
The heart is a muscular organ and is responsible fore pumping blood around the body, and on average the human heart beats at 72 beats per minute.   When looking at the heart (see diagram) it is important to remember that the left and right side are reversed (due to the way we are looking at it).   The right side of the heart deals with deoxygenated blood and pumps it into the lungs.   The left side of the heart deals with oxygenated blood, and pumps it around the entire body.   The lower chambers of the heart is know as the ventricles and is more muscular and stronger than the upper chambers, known as the atria.   This is because a large volume of blood is pumped from the ventricles up through the atria and around the body.   It is important to maintain a healthy heart, as it reduces the risk of developing high blood pressure and cholesterol levels, as well as developing heart disease.   By eating healthy and doing regular exercise we are able to reduce theses factors as well as reducing stress levels too.


Main:
The heart is a muscular organ that it part of the cardiovascular system.   It is located between the lungs, behind the sternum and is approximately the size of a fist.   The heart is protected by a membrane called the pericardium which surrounds the heart and secretes a fluid that reduces friction when the heart beats.   The atria’s job is to receive blood and the ventricles job is to be filled with blood and send it to everywhere in the body.   There are three layers which make up the wall of the heart.   The outer layer is epithelial tissue, the middle layer is cardiac muscle and the inner layer is connective tissue.   Deoxygenated blood is pumped from the right ventricle and into the lungs, where the blood is regenerated with oxygen and returned through the pulmonary vein.   The following explains the hearts role and internal structure in more detail.

There are four chambers in the heart, the top of the heart has a right and left atrium...