Ask a Teacher

Search



Explain the working of heart.
 The heart has four parts, the left ventricle  and the right ventricle which are both at the bottom of the heart, and the left atrium  and the right atrium at the top. A wall of muscle called the septum separates them.The walls of the heart are made of really strong muscles that squeeze and relax to pump blood around the body. Between them, small valves open and shut with each heartbeat so the blood can only flow in one direction.

The left side of the heart gets the blood from the lungs where it has collected oxygen, and pushes it all round the body through the arteries and the tiny blood vessels called capillaries This blood is a bright red colour.

The right side of the heart gets the blood after it has taken oxygen round the body and sends it back to the lungs for some more oxygen. This blood is carrying carbon dioxide which gets breathed out when it reaches the lungs. This blood looks a darker red colour.

So the main job of the heart is to pump blood to every part of the body. The blood carries oxygen and all the food, vitamins and minerals that our body needs to move, think, grow and repair itself. At the same time the blood picks up stuff that our body doesn’t need and takes it to those parts of our body that get rid of waste (your lungs, kidneys and liver).

How the heart functions

In the first stage, the upper chambers (atria) contract at the same time, pushing blood down into the lower chambers (ventricles).
    Blood is pumped from the right atrium down into the right ventricle and from the left atrium down into the left ventricle.

    In the second stage, the lower chambers contract to push this blood out of the heart to either the body via our main artery (aorta) or to the lungs to pick up oxygen. The heart then relaxes – known as diastole. Blood fills up the heart again, and the whole process, which takes a fraction of a second, is repeated

The different sides of the heart have different functions.

    On the right side, the upper chamber fills with oxygen-depleted blood from our body and pushes it via the lower chamber and the pulmonary artery back to the lungs. Here blood picks up oxygen and releases carbon dioxide.
    On the left side, the upper chamber fills with oxygen-rich blood from the lungs. This is pumped via the lower chamber into the aorta and out to the body to provide cells with oxygen..

On average, most people have a heart rate of around 72 beats per minute at rest. This varies according to fitness, age, exertion and general health..

Each heart beat is triggered by an electrical pacemaker - a group of cells in the heart that have the ability to generate electrical activity. They cause electrical impulses to spread over the heart and make it contract.

The largest natural pacemaker of the heart is called the sinoatrial or SA node and is found in the right atrium. From it, specialised groups of cells that carry the electrical charge lead off to the rest of the heart.


comments powered by Disqus