How your heart works

What is your heart?

Your heart is about the size of your clenched fist. It lies in the front and middle of your chest, behind and slightly to the left of your breastbone.

It is a muscle that pumps blood to all parts of your body to provide it with the oxygen and nutrients in needs to function. 

Your heart has the right and left separated by a wall. Each side has a small chamber called the atrium (pronounced ay-tree-um), which leads into a large pumping chamber called a ventricle (pronounced ven-tri-kl). There are 4 chambers:

  • left atrium
  • left ventricle
  • right atrium
  • right ventricle.

diagram of heart showing top to bottom superior vena cava, aorta, right and left pulmonary arteries, left and right ventricles, right atrium and apical impulse at bottom left

The right side of your heart

The right side of your heart collects blood on its return from the rest of your body.

The blood entering the right side of your heart is low in oxygen. This is because oxygen is removed from your blood as it circulates through your body's organs and tissues. 

Your heart then pumps the blood to your lungs so it can receive more oxygen.

Once it has received oxygen, your blood returns directly to the left side of your heart, which then pumps it out again to all parts of your body.

The left side of your heart

The left ventricle of your heart is larger and thicker than the right ventricle. This is because it has to pump the blood further around the body, and against higher pressure, compared with the right ventricle.

To make sure your blood flows in the correct direction, valves guard the entrance and exits of your hearts chambers.

Where to get help

  • Always dial triple zero (000) to call an ambulance in a medical emergency
  • See your doctor
  • Visit healthdirect (external site) or call 1800 022 222
  • Phone the Heart Foundation Helpline on 13 11 12

This information provided by

Heart Foundation logo

Heart Foundation

This publication is provided for education and information purposes only. It is not a substitute for professional medical care. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your healthcare professional. Readers should note that over time currency and completeness of the information may change. All users should seek advice from a qualified healthcare professional for a diagnosis and answers to their medical questions.

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