How the heart works

Your heart is a powerful muscle that never takes a rest from pumping blood throughout your body. Roughly the size of your clenched fist and sitting just to the left of your breastbone, it beats around 100,000 times a day.

In the time it takes you to read this page, your heart and blood vessels will pump your entire blood supply – some five litres – through your entire body.

Get the facts on How Your Heart Works

Your heart is your body's engine

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By circulating blood to your organs, muscles, and body tissue, your heart does two things – it distributes oxygen and nutrients to where they’re needed, and it gets rid of waste through your kidneys, liver and lungs. When it doesn’t work properly, your organs can suffer. And if it stops, so do you.

Together, your heart and network of blood vessels form your circulatory, or cardiovascular system (from the Latin ‘cardio’ meaning heart and ‘vascular’ referring to blood vessels). While your blood vessels –arteries, veins and capillaries carry the blood throughout your entire body, it’s your heart that keeps the blood moving.

Anatomy of your heart

Your heart is divided down the middle into the left and right sides, by a muscular wall called the septum. The right side receives returning blood from your body via the pulmonary arteries and pumps it through the lungs where it picks up oxygen and nutrients. The oxygen and nutrient rich blood is received by the left side of your heart and pumped out to your body via the large aorta.

Special arteries, called the coronary arteries, branch out of the aorta as it leaves the left ventricle and spread across the myocardium – the special muscle tissue that forms the walls of the heart – giving your heart its own dedicated supply of blood and nutrients.

Each side of your heart has two chambers. The smaller upper chambers, which collect blood, are the left atrium and right atrium – together known as 'the atria'. The lower and larger pumping chambers are the left ventricle and right ventricle –collectively, they’re called the “ventricle”.

Four valves – one inlet valve and one outlet valve in each of the ventricles – precisely control the flow of blood through your heart’s chambers as your heart rhythmically contracts and relaxes in a perfectly synchronised cycle (“the cardiac cycle”). For the average resting adult, this occurs about 70 times every minute.

The mechanism driving the cardiac cycle is the heart’s electrical system, which starts in a small group of cells called the sinoatrial (or sinus) and atrioventricular nodes. Sometimes called the heart’s ‘natural pacemaker’, the sinoatrial node (SA) and atrioventricular node (AV) spread electrical impulses through the atria and ventricles. This coordinates the muscle contractions that push blood through the four chambers of the heart, and sets the pace for your heartbeat.


With a stethoscope, your doctor can hear the two distinctive heart sounds of your heartbeat – ‘doom DOOM’ – that are caused by the heart valves closing. The softer, first ‘doom’ is the sound of the ventricle’s inlet valves closing after blood enters them from the atria. The stronger second ‘DOOM’ is the sound of the ventricles’ outlet valves closing after blood has been pushed out of the heart through your body.

Technically, a heartbeat is divided into two parts – the contraction of the ventricles that pushes blood out of the heart (called systole), and the relaxation phase when the atria and ventricles fill with blood (known as diastole).

What's a normal heart rate?

Heart rates differ between people, depending on many things including age, level of fitness, and state of mind. It’s normal for your heart rate to go up throughout the day depending on what you’re doing – running to a meeting, taking the stairs or caught in traffic.

As a general rule, if you’ve been sitting quietly for ten minutes, and don’t have too much on your mind, (a state known as the resting heart rate), an adult woman’s heart rate would usually be between 72-80 beats per minute, while a man’s would be between 64-72 beats per minute.

Is there a maximum heart rate?

While an elevated heart rate is normal when you exercise, get stressed or excited, you should aim to stay within your maximum heart rate, particularly when you’re doing vigorous exercise.

You can work out your maximum heart rate by subtracting your age from the number 220. For example, a 55 year old would have a maximum heart rate of 165.


How do I take care of my heat?

37% of all deaths this year will be a result of a cardiovascular incident such as a Heart Attack and many more will be disabled due to cardiovascular related episodes such as Strokes.

Yet, diseases of the heart and cardio system (Cardiovascular Disease) remain one of the most preventable diseases known. Cardiovascular disease develops over many years and although you can’t do anything about some Risk factors such as your gender, age or family medical history, you can reduce your Risk significantly by knowing the controllable Risk factors and managing them with life style changes, regular monitoring and supplements.

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Don't Smoke

If you smoke, there has never been a better time to quit. Nicotine replacement patches or prescription medications are effective in reducing the cravings.

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Check Your Cholesterol Levels Regularly

Do you know your cholesterol levels? Most people don't. Information is key, so knowing where you stand is the first step in keeping track and maintaining your heart health. You can order a Blood Pathology Request through Results are mailed directly to you and you can track your results using the My Heart Health section of

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Take Supplements Daily

Supplements are a great way to make sure you're getting your daily requirement of heart healthy nutrients. Supplements such as Omega 3 fish oil, Vitamins C and E and Coenzyme Q10 can be very beneficial to your heart health.

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Keep Your Blood Sugar In Range

If you have diabetes, follow your doctor’s direction and keep your blood glucose within a healthy range. Even if you don't have diabetes, stick to a low GI (Glycaemic Index) diet. You won’t be hungry and your blood sugar levels will be stable.

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Check Your Blood Pressure Regularly

Order a blood pressure monitor and keep track of your blood pressure weekly. You can record your results in the My Heart Health section of Aim to keep your blood pressure out of the danger zone - below 140/90mmHg. If your blood pressure is consistently high see your doctor.

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Be Active

Get a minimum of 30 minutes of moderate physical activity every day, or at least 2 hours in total per week. Even better, if you can get 4 hours of sweaty activity per week, you'll help lower your Risk of cancer too.

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Watch Your Waistline

Get your waist measurement to your 'low risk' zone. Men should keep it below 95cm and women should be below 80cm. Aim for a Body Mass Index of less than 25. You can track your progress in the My Heart Health section of

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Seek Happiness

Happiness is good for the heart. Just as negative emotions such as depression, anger, and hostility are risk factors for heart attack and stroke, studies show that happiness seems to protect the heart.