Blood is made up of cells, platelets and plasma
Blood transports various substances around the body through the circulatory system. For example, blood carries oxygen and glucose to the muscles and takes carbon dioxide away from them.
Blood is made up of:
- Red blood cells- The job of red blood cells is to transport oxygen from the lungs to the rest of the body. They don't have a nucleus so they can be packed full with haemoglobin- a substnace that binds with oxygen. Red blood cells have a biconcave shape to give them a large surface area for exchanging oxygen.
- Plasma- This is the liquid that carries nutrients (e.g. glucose and amino acids), antibodies, hormones and waste (e.g. carbon dioxide and urea).
- White blood cells- They help to fight infection by protecting your body against attack from microorganisms.
- Platelets- These are small fragments of cells that help the blood to clot at the site of a wound.
Double Circulatory System
Humans have a double circulatory system- two circuits joined together.
The first circuit pumps deoxygenated blood to the lungs to take in oxygen. The blood then returns to the heart.
The second one pumps oxygenated…