4. The Circulatory System

The circulatory system is made up of blood, the heart, and blood vessels. It transports nutrients and oxygen throughout your body and carries away wastes.


Blood vessels are tubes that carry blood around your body. There are 3 types:

1. An artery is a vessel that carries blood from your heart to other parts of your body
2. A vein is a blood vessel that takes blood from your body back to the heart.
3. A capillar connect arteries to veins. These vessels are so thin that oxygen and nutrients can pass  through their walls and into body tissues, and carbon dioxide and waste can pass into the capillares.

Resultado de imagen de arteries veins and capillaries


Blood is made up of plasma and three kinds of cells: red blood cells, white blood cells, and platelets. - Plasma is the liquid part of the blood that carries these materials, and it is mostly water.
- Red blood cells bring oxygen to parts of your body, 
- White blood cells help your body fi ght diseases
- Platelets help your blood clot if you get a cut.


It is a muscular organ (the size of your fist) inside the rib cage, between the lungs, that pushes (moves) blood through the blood vessels. It beats between 60-100 times / minute (around 100.000 times / day, 35 million times/year, 2 and a half billion times/life time).

It is divided into four parts or four chambers:

- upper chambers: right atrium and left atrium 
- lower chambers: right ventricle and left ventricle.

The left part of the heart and the right part are divided by the septum 


Blood circulates around your body in 2 circuits: pulmonary ciruclation and general circulation.

- Pulmonary circulation: between the heart and the lungs to take oxygen and expulse carbon dioxide
- General circulation: between the heart and the rest of the body to give oxygen and nutrients to the cells through arteries and pick up carbon dioxide to expulse it.



Science Kids - Fun Science & Technology for Kids!
Interesting facts about blood          Interesting facts about the human heart


Quiz: Heart & Circulatory System

Heart     Resultado de imagen de heart
Illustration of the Heart