Blood and Its Components

Blood is a tissue made up of several different types of cell suspended in a liquid called plasma. Each component of blood has a specific role in maintaining life. This lesson covers the composition of blood and the functions of each component, as required by the AQA GCSE Combined Science Trilogy specification (8464).

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Composition of Blood

Blood is made up of four main components:

graph TD
    B["Blood"] --> P["Plasma (~55%)"]
    B --> RBC["Red blood cells (~45%)"]
    B --> WBC["White blood cells (<1%)"]
    B --> PLT["Platelets (<1%)"]

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Plasma

Plasma is the straw-coloured liquid part of blood. It makes up about 55% of blood volume and acts as the transport medium, carrying dissolved substances around the body.