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Biology chapter 6: transport in humans, blood circulation - Coggle Diagram

- - - - the absence of the nucleus, this allows more space for more haemoglobin in the red blood cells to transport more oxygen
      - they have a biconcave shape, this increases the surface area to volume ratio for efficient diffusion of oxygen
      - they contain haemoglobin, that can combine with oxygen. in the lungs where the oxygen concentration is high, haemoglobin binds with oxygen to form oxyhaemoglobin which is bright red, in tissues where oxygen is low, oxyhaemoglobin releases oxygen into the tissue cells, and the oxyhaemoglobin turns back into haemoglobin, which is purpurlish-red
      - they are elastic, this allows them to squeeze through tiny blood cells
    - - phagocytes, their main function is to perform phagocytosis, the process where a white blood cell engulfs, or eats and destroys foreign particles
      - lymphocytes, they produce antibodies that recognise and destroys foreign particles like bacteria and viruses, cause bacteria to clump together for easy ingestion by phagocytes, and neutralise the toxins produced by bacteria
      - white blood cells are irregular in shape, and they each have a nucleus
    - - blood clotting, platelets are involved in converting soluble protein fibrinogen into INSOLUBLE fibrin threads with the help of enzymes, the fibrin threads then entangle blood cells and the whole mass forms a clot or a scab, the clot seals the wound, thus preventing microorganisms and the excessive loss of blood
    - - similarly, a foreign tissue my be rejected by the white blood cells which will produce antibodies to destroy it, this is called tissue rejection, however this will not happen if the tissue that is transplanted comes from the same person. if the tissue comes from another human, a tissue match is necessary to reduce the risk of rejection, the tissues of the donor and the recipient must be as genetically similar as possible
- - - - blood group B, which is covered in round and circular antigen B, and has antibody a, which are sharp and triangular and cannot react with antigen B, it is compatible with group B and group O
      - blood group AB, contains the triangle antigen A and the circular antigen B, because of this, there are no antibodies present in the plasma, and because they have no antibodies, they are compatible with every blood group, and group AB is known as the universal acceptor
      - blood group A, red blood cells are covered in antigen A which are in a triangle shape, and has antibody b, which has a rounded edge and cannot react with antigen A, in the blood plasma, it is compatible with blood group A and blood group O
      - blood group O, has no antigens, but has antibodies A which are sharp and triangular and B which have rounded edges, because it has no antigens, it is compatible with every blood group and are known as the universal donor, however, it cannot RECEIVE any blood group except group O itself
- - - - small vessels that connect the arteries and the veins, one cell thick, and is the site where the exchange of gases, nutrients and waste products, between blood in capillaries and intestinal fluid, all this happens mainly due to diffusion
      - tiny spaces between tissue cells contain a colourless liquid, tissue fluid, this fluid transports dissolved substances between tissue cells and blood capillaries, dissolved food substances and oxygen diffuse from the blood into the tissue fluid, then move into the cells, waste products diffuse from the cells into the tissue fluid, they are then transferred through the blood capillary walls into the blood, the blood transports these waste substances to the excretory organs for removal
    - - arteries receive blood directly from the heart, and need to withstand the high pressure of blood forced out of the heart, the blood flow in the arteries are fast, so they have thick muscular, and elastic walls, the thick elastic walls withstand the high pressure in the artery, transports oxygenated blood from the heart to all parts of the body
        
        naturally, arteries transport oxygenated blood, but the pulmonary artery is the only artery that transports deoxygenated blood
    - - veins transport deoxygenated blood back to the heart, this walls and less elastic tissue as the blood flow is slower and lower blood pressure, also have valves to prevent backflow of blood
        
        veins transport deoxygenated blood except the pulmonary vein, which transports oxygenated blood from the lungs to the heart
- - - - the right ventricle then contracts and blood leaves the heart through the pulmonary arch
        
        blood then leaves the heart and enters the lungs via the pulmonary artery for gaseous exchange
        
        after gaseous exchange, oxygenated blood leaves the lungs and enters the left atrium via the pulmonary vein
        
        blood then enters the left ventricle when the bicuspid valve opens, where it is pumped out of the heart at high pressure, the left ventricle is where there is the most pressure in the heart
        
        blood then leaves the heart via the aortic arch and is pumped to the rest of the body