The cardiovascular system 

The cardiovascular system is made up of:

  • The heart
  • Blood vessels (veins and arteries)
  • Blood

All of these parts are connected. The heart pumps blood through the blood vessels.

Inside the blood, there are red blood cells which carry oxygen and white blood cells which fight off germs. Blood also has platelets which are really important to help blood clot. When we cut ourselves, platelets form a special wall that stops the blood from pouring out of our bodies. That’s very clever!


Post Image

All the different blood cells float in a liquid called plasma. As blood circulates through the body, it picks up different things on the way. It picks up oxygen from our lungs, nutrients from the food we eat and carbon dioxide and waste products from our cells. 

Not everyone’s blood is the same. Blood is divided into four main types: type A, B, O and AB. When doctors do blood transfers they have to make sure the blood of the donor matches the blood of the sick person.


Post Image

Depending on what you’re doing, the heart can beat faster or slower. If you’re sitting still, the heart beats slower than if you’re running. When you do exercise the heart beats faster to get more oxygen to your muscles.

 

Fun facts

  • A wasp, called the fairyfly, has the smallest heart of all living creatures.
  • The earliest known case of heart disease was found in an Egyptian mummy over 3,500 years old.
  • Whales have the largest heart of all mammals.
  • On average a man’s heart is heavier than a woman’s heart.
  • A woman’s heart beats slightly faster than a man’s.
  • The first open-heart surgery occurred in 1893 by Daniel Hale Williams.
  • The American pygmy shrew is a very small mammal but it has the fastest heartbeat: 1,200 beats per minute!
  • The giraffe’s heart has much thicker muscles than other animals because it has to carry blood up the giraffe’s long neck.


Post Image

  • The adult heart beats about 72 times a minute. That’s around 100,000 times a day! 
  • To make sure blood only goes one way, the heart has four valves that open and close, stopping blood from moving back where it came from. 
  • The sound the heart makes when we listen to it is from the valves opening and closing.
  • The heart does more physical work than any other muscle in the body.
  • The first ever successful heart transplant was done in 1967 by Dr. Christopher Barnard.
  • The heart can still beat outside of the body! As long as it has enough oxygen it will continue to beat from its own electrical impulse.
  • If you stretched out all the arteries, veins and capillaries that transport blood through your body, they would be 60,000 miles long!
  • The heart pumps so much blood back and forth in one day, the equivalent of around 38,400 glasses of water a day!
  • Blood pressure in the heart can squirt blood over 30 feet into the air (that’s just under 10 metres).
  • Blood cells live for around 4 months.