Friday

Chapter 25: Transport of materials in Animals

The system responsible for the transport of materials in humans is called the Circulatory system


The Circulatory system:

  • Supplies oxygen and digested food to all parts of the body quickly
  • Is made up of the heart - the pump that pumps blood to all parts of body, blood vessels - Veins, Arteries, and the Capillaries, Blood
Organ: Heart
Function: acts like a muscular pump that contracts and relaxes to pumps blood to all parts of body, has valves to prevent the backflow of blood.

Organ: Blood vessels
         - Veins
         - Arteries
         - Capillaries
Function/ : Veins - transports mainly deoxygenated blood towards the heart
Feature            - has thin walls as the pressure is low
             Arteries - transports mainly oxygenated blood away the heart
                       - has thick walls as the vessels need to withstand the pressure caused by the pump                             of the heart
            Capillaries - very thin blood vessels located between the cells of our body
                        - has very thin walls to allow substances to pass through to and fro the cells and                                 blood 
Organ: Blood
Function/ : Plasma - yellow liquid made up of mainly water and dissolved substances like digested food
Feature     White blood cells - kills bacteria and fight diseases
                                  - larger than red blood cells, live for only a few days
              Red blood cells - transports oxygen around the body                                                                                   - biconcave shaped so as to increase the surface area of the cell and to increase                                   the rate of exchange of oxygen
                                - has no nucleus                     
                                - Contain a red pigment - hemoglobin ( iron )
              Platelets - tiny pieces of other blood cells
                         - clot blood when there is wounds 
                                 

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