About the heart

How does it work and what does it do?

How does your heart work?

Your heart is roughly the size of an apple and is essentially the muscle that controls your circulation, that is the movement of blood around your body.  The blood carries oxygen and nutrients all around your body, and then takes away unwanted carbon dioxide and waste products.

Your heart is constantly pumping around five litres of blood around your body, and this is called circulation.  Together, you heart, blood and blood vessels make up your cardiovascular system.  Your blood vessels are the channels that the blood is pumped through and there are different types:

  • arteries – they carry oxygen-rich blood from your heart to all parts of your body, getting smaller as they get further away from the heart
  • capillaries – they connect the smallest arteries to the smallest veins, and help exchange water, oxygen, carbon dioxide and other nutrients and waste substances between the blood and the tissues around them
  • veins – they carry blood, lacking in oxygen, back towards your heart, and get bigger as they get nearer your heart

Blood vessels are able to widen or narrow depending on how much blood each part of your body requires. This action is partly controlled by hormones.

The pumping action of your heart is controlled by electrical signals which tell the muscle when to contract and relax – this is your natural pacemaker.  The pumping action squeezes the blood through the blood vessels and around the body.

Blood pressure

Your blood pressure is a key element to moving your blood around your body and is the measurement of the pressure within your arteries.  It plays a vital role in the way your heart delivers fresh blood to all your blood vessels:  blood must be under pressure to travel throughout your body quickly enough.  This is created by the relationship between:

  • your heart’s pumping action
  • the size and stretchiness of your blood vessels
  • the thickness of the blood itself

One heartbeat is a single cycle in which your heart contracts and relaxes to pump blood.  At rest, the normal heart beats approximately 60 to 100 times every minute, and it increases when you exercise.

How does a healthy heart work?

Watch this British Heart Foundation clip on how a healthy heart works.

What can go wrong?

Problems with the cardiovascular system can include:

  • heart attack – caused by a blood clot
  • angina – due to narrowed coronary arteries
  • stroke – due to a blood clot in the brain
  • heart disease – atheroma – caused by blocking of the arteries
  • arrhythmia – due to electrical signals within the heart not being regular/too fats/too slow
  • High blood pressure – which increases the stresses on the heart function
  • Heart failure – when your heart can’t keep up with your body’s demands

Find out if you are at risk

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