White blood cells 

We’ve all heard of red blood cells, they’re the cells that swim about in the blood, transporting oxygen to our body. But what about the white blood cells? Have you heard of them? 

White blood cells are in charge of protecting us, their job is to find any harmful bacteria or viruses in the body and destroy them.

Both red blood cells and white blood cells come from stem cells which are found inside our bones, in the part called the bone marrow.

Red blood cells travel in a liquid called blood and white blood cells travel in a liquid called lymph. 

There are lots of different types of white blood cells. Let's get to know some of them: 

Neutrophils are the hunters, they look for the naughty pathogens that are roaming inside the body.

Lymphocytes fight off bacteria and viruses. There are two types of lymphocytes:

B cells are found in bone marrow: these produce antibodies which attach to germs letting other cells recognise the invaders.

T cells are found in the thymus, they look for the invaders and kill them. T cells also call other cells for help.

Macrophages are big eating cells. The biggest blood cells of all. They eat up pathogens and any leftovers caused by other white blood cells during the attack.

The lymphatic system

The lymphatic system is made up of lymphatic vessels and lymph nodes. It carries lymph through our bodies and lymph carries white blood cells. This whole system makes up our immune system.

As lymph travels through the body it carries white blood cells to areas that are infected. 

Some pathogens are taken to lymph nodes where they are filtered and destroyed. These lymph nodes or glands swell up when the immune system is in action. Doctors often feel the lymph nodes along our necks when we’re sick. They’re touching to see if they’re swollen. If they are it proves they are fighting off something. 

Lymph nodes are also found behind our knees and in our armpits.

Other defences

The skin is one of the first barriers of defence, it stops germs from coming inside and produces oil to help fight off bacteria.

The next point of attack is the mouth, nose and eyes. These are covered with a mucous membrane. If you open your mouth or look up your nose you will see this reddish lining. This traps bacteria, viruses and dust. The little hairs up our nose help trap bigger things.

The saliva in our mouths and the tears in the eyes contain enzymes which break down pathogens and the acid inside our stomachs attack off any cheeky pathogens that were hiding in our food.

Interesting  facts

• Around 80% of the activity of the immune system takes places in the intestines.
• Our stomachs and intestines are filled with hundreds of bacteria that help us digest food. These are good bacteria and we need them to stay strong.
• The spleen plays an important role to the immune system. It produces antibodies and white blood cells. 
• Laughter is good for the immune system.
• The first milk a mother produces when her baby is born is called colostrum. It is full of the mother's antibodies. When the baby drinks this milk it receives all these antibodies which help its immune system be stronger. 
• Vaccinations contain dead pathogens. The immune system doesn’t realise they’re dead so it attacks them and creates the antibodies to fight it off. When the real disease tries to attack the body, the body already has all the defences it needs.
• One of the first responses of the immune system is inflammation, redness, swelling and pain.