How your heart works

  • Your heart is a muscular pump made up of four chambers: the right and left atria and the right and left ventricles.
  • Your heart requires its own blood supply to keep it working efficiently.
  • The pumping action of the four chambers is coordinated by electrical signals telling the heart when to contract (squeeze) and relax.
  • A series of four valves keep the blood moving in the right direction.

In order for your heart to function properly, it needs all of the above to work efficiently.

Network of blood vessels

Blood is pumped around your body through a network of blood vessels:

  • Arteries transport oxygen-rich blood from your heart to all parts of your body. The arteries get smaller as they get further away from the heart.
  • Capillaries are the smallest of blood vessels. They connect the smallest arteries to the smallest veins. This is where oxygen, carbon dioxide, nutrients and waste products are exchanged.
  • Veins carry blood, lacking in oxygen, back towards your heart. The veins get bigger as they get nearer your heart.

Blood vessels have a layer of spiral muscle within their walls. This makes them able to widen or narrow depending on how much blood each part of your body requires. The action on these muscles is a very complex mechanism which is partly controlled by hormones.

How blood flows through your heart

How blood flows through your heart

Movement of blood through your heart

  • Blood from the muscles and organs of your body enters the right side of the heart into the right atrium (1)
  • It is then pumped into the right ventricle (2)
  • From there the heart pumps the blood to your lungs, where it takes up oxygen and gets rid of the carbon dioxide it has been carrying (3)
  • This oxygen rich blood then enters the left side of your heart into the left atrium (4)
  • It is then pumped into the left ventricle (the strongest of the four chambers) (5)
  • From there it is pumped into the aorta (largest blood vessel in the body) (6) to all parts of your body including the heart muscle itself

Blood pressure

Blood pressure is the measurement of the pressure within the arteries. It plays a vital role in the way your heart delivers fresh blood, containing the oxygen and nutrients required throughout your body, to all the blood vessels.

In order for blood to travel throughout your body, quickly enough, it has to be under pressure. This pressure is created by the relationship between three things:

  • Your heart's pumping action
  • The size and stretchiness of your blood vessels
  • The thickness of the blood itself
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