What is the circulatory system?

Your circulatory system is also called the cardiovascular system or vascular system.

It keeps blood flowing to every part of your body. Blood carries and moves oxygen, nutrients and hormones to your cells to help them:

• have energy
• grow
• repair damage

Your circulatory system also removes carbon dioxide and waste products that your cells don't need.

Your circulatory system includes:

• blood — made up of red and white blood cells, plasma and platelets
• heart — a muscular organ that pumps blood to all parts of your body
• blood vessels — arteries, veins and capillaries that carry your blood

Your circulatory system works closely with other systems in your body, such as your respiratory system (lungs).

How does the circulatory system work?

Your circulatory system moves blood around your body to deliver oxygen to your cells.

Blood that is low in oxygen flows into the right atrium of your heart (one of the heart's 4 chambers). It then moves into the right ventricle, which pumps blood to your lungs. In the lungs, your red blood cells collect oxygen and release carbon dioxide, which you then breathe out.

The oxygen-rich blood returns to the left atrium of your heart (one of the heart's 4 chambers). It then moves into your left ventricle. The left ventricle pumps oxygen-rich blood through the aorta and into your arteries, sending it to all parts of your body.

Along the way, blood gets nutrients from the food in your small intestine.

As your blood flows through tiny blood vessels called capillaries, it delivers oxygen and nutrients to your cells. It also removes carbon dioxide and waste products. Your blood, now low in oxygen again, travels through your veins back to your heart's right atrium and the cycle starts over.

What are common health conditions of the circulatory system?

Cardiovascular disease

Cardiovascular disease (CVD) refers to all diseases of the heart and blood vessels.

Most CVD happens when fatty substances called plaque or atheroma build up inside blood vessels. Over time, this makes the blood vessels narrow, so less blood can flow through. Sometimes the blood vessels can get blocked completely. This process is called atherosclerosis.

Atherosclerosis can lead to coronary heart disease. If the blood vessels to your heart narrow, your heart muscles get less oxygen and nutrients. This can lead to angina or a heart attack. A heart attack is an emergency and needs urgent medical help. The most common symptom of heart attack or angina is chest pain.

Stroke

A stroke happens when the blood supply to part of the brain is blocked or an artery bursts. A stroke is a medical emergency and needs urgent treatment.

Read more about heart and cardiovascular conditions.

High or low blood pressure

When your heart pumps blood into your arteries, the blood pushes against the artery walls. This is blood pressure. It is measured in millimetres of mercury (written as mmHg). Most doctors consider a healthy blood pressure to be:

• higher than 90/60mmHg
• lower than 140/90mmHg

High blood pressure (hypertension) may increase your chance of cardiovascular disease. It is the most common circulatory system condition.

Low blood pressure (hypotension) is a sign of good health for some people, but can be a problem for others. Signs of low blood pressure include feeling dizzy or fainting.

When should I see my doctor?

The best way to know if your circulatory system is healthy is to see your doctor for a heart health check. If you are eligible, this check is covered by Medicare. The earlier heart or blood vessel conditions are found, the sooner they can be treated.

If you already have high blood pressure, it's important to have regular heart health checks with your doctor.

See your doctor if you notice:

• chest pain
• shortness of breath
• cold hands or pain in your feet
• a fluttering heart (palpitations)
• swelling in your feet or ankles (oedema)

Low blood pressure is only a problem if it affects how your body works or how you feel. It can sometimes be a sign of another health condition. See your doctor if you:

• feel lightheaded, unsteady or dizzy
• have blurry vision
• faint

Can health conditions of the circulatory system be prevented?

Some risk factors, such as your age, family health history or ethnic background, can't be changed. There are things you can do to help keep your heart healthy and reduce your risk of cardiovascular disease:

• Eat a heart-healthy diet, including healthy fats.
• Drink water and avoid sugary drinks and alcohol.
• Aim for physical activity every day.
• Quit smoking.
• Lower your salt intake.

Some medicines can also affect your blood pressure and circulatory system.

Speak to your doctor if you have questions or want help to lower your risk of heart disease.

Resources and support

• Heart Foundation offers more information on heart disease.
• Department of Health, Disability and Ageing offers more information on cardiovascular conditions.
• Check your risk of cardiovascular disease on the AusCVDRisk website.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available 24 hours a day, 7 days a week.

Do you prefer to read in languages other than English?

• The Heart Foundation has resources in many languages.
• Health Translations has translated resources about heart health.

Looking for information for Aboriginal and/or Torres Strait Islander people?

• For help to stop smoking, call Quitline or Aboriginal Quitline on 13 7848 (13 QUIT). You can visit their website or request a call back.
• St Vincent's Heart Health has resources on heart health, risks and common heart conditions.