blood

• plasma is the liquid part of blood made up of a mixture of water with dissolved substances such as sugar and salts
• plasma transports components of blood (cells, nutrients, wastes, hormones, protein, antibodies) through the body
• Formed elements are any cell or cell-like structure in the blood
• rbc = erythrocytes
• rbc are made in the bone marrow and only live up to 120 days because they do not contain a nucleus. they are destroyed in the liver and spleen
• rbc are biconcave in shape which means they are flattened in the middle on both sides
• rbc do not contain a nucleus which increases flexibility and allows for more surface area to carry haemoglobin
• Haemoglobin is the substance that combines with and carries oxygen, it turns red when combined with oxygen
• rbc transports oxygen from the lungs to the cells throughout the body
• wbc = leucocytes
• wbc can live for a few minutes fighting infection or years when not fighting infection
• wbc are larger than red blood cells, but fewer in numbers
• wbc contain a high number of lysosomes which help in protecting the body from infections
• most wbc can change shape to fit between cells
• wbc plays a role in protecting the body from infections. through phagocytosis, it removes dead or injured cells and invades microorganisms.
• wbc recognises substance to be engulfed

  it extends its cell membrane around substance

  a vesicle is formed

  the vesicle is brought into the cell and fuses with a lysosome
• platelets = thrombocytes
• platelets are fromed in the bone marrow and live up to 7 days
• platelets are small fragments of cells and one third the size of red blood cells
• When a blood vessel is injured, platelets adhere to the lining and form a scaffold for the coagulation of blood to form a clot