The Blood

The Blood

The circulatory system in the blood consists of the heart and the blood as a transport system. The blood is made up of four components;

• Red Blood cells (RBC)
• White Blood cells (WBC)
• Platelets
• Plasma

Red blood cells are designed to carry as much oxygen as possible around the body for respiration. They are biconcave shaped in order to increase surface area: volume ratio to carry the oxygen and they contain a chemical called haemoglobin which allow them to carry oxygen. Adaptations include;

• They are biconcave to increase surface area to volume ratio
• The contain haemoglobin to carry oxygen
• The have no nucleus for more haemoglobin to carry more oxygen
• They have thin cell membranes for oxygen to easily diffuse through

It's important to know that when inhaling carbon monoxide, it can take the place of the oxygen which can cause you to suffocate!

Abstract Marble painting (Cassi Josh)

55% of the blood consists of plasma which is a key transportation fluid for mineral ions, waste products like carbon dioxide, urea, heat and hormones.

White blood cells are an important part of the blood which play an important role in the immune system. They help to ingest pathogens and produce antibodies to fight off and control these pathogens. Around 25% of the white blood cells in the body produce antibodies which bind specifically to pathogens. After attaching to the antigens (markers on the surface), they can do a number of things;

• Neutralise the toxins the pathogen produces
• Clumping together the pathogens to make phagocytosis easier 
• Flag up the pathogen to the phagocytes

Check out my disease module to look at how Memory Cells 'remember' the specific antibodies required in order to self-vaccinate against the disease!

The famous Phagocytes make up 70% of all WBCs and these are, like lymphocytes, part of the immune system. However, unlike lymphocytes, they don't produce antibodies; they engulf them! After the pathogens are detected, often with help from the lymphocytes, the phagocytes engulf them in a vacuole enclosed and digest the pathogens into amino acids using enzymes. 

Abstract Painting (Jason Filipe)

A small proportion of the blood is made up of platelets which are involved in clotting of the blood for example when we get a cut, the scab forms is due to these amazing platelets (without them a tiny cut could be fatal as we bleed to death!). Clots form as the platelets release proteins called fibrinogen which bind together to from fibrin mesh. This fibrin mesh causes RBC to become trapped in it which causes a clot over the wound.