Transporting Materials

Transporting Materials

1. The Circulatory System

   • Definition: The network of veins, capillaries and arteries that transports blood around the body.
   • The Heart
     • The heart operates a double circulation in which one goes to and from the lungs and the other goes to and from the rest of the body.
     • Pumps the blood around the body and is mostly made up of muscle tissues.
     • • Arteries
         • Arteries have thick walls containing muscle and elastic fibres.
         • If they begin to narrow, stents are used to keep them open.
       • Veins
         • Have thin walls and often have valves to prevent blood going backwards.
       • Capillaries
         • Capillaries are thin-walled and allow diffusion of materials into and out of the blood into the surround organs.
     • 1. Blood enters the heart at the atria, which contracts and forces the blood into the ventricles.
       • 2. The ventricles contract forcing the blood out of the heart.
     • Valves in the heart ensure that no blood flows the wrong way
     • Blood from the heart goes into arteries and comes back in veins.

2. Artificial Parts

   • Artificial Blood
     • Advantages
       • Increased shelf life compared to normal blood.
       • Does not need refrigeration.
       • More efficient at carrying oxygen.
       • No need for blood match.
     • Disadvantages
       • Short lasting for use.
       • It is very expensive.
   • Artificial Heart
     • Advantages
       • No chance of it being rejected.
       • Keeps the patient alive whilst waiting for a donor.
     • Disadvantages
       • Requires a power supply.
       • Surgery can lead to bleeding and infection.
       • Blood does not flow as well so blood thinners may be needed to prevent clotting.
       • Parts can wear out or stop over time.
   • Artificial Heart Valves
     • Advantages
       • Success rate is high.
       • Prolong life expectancy.
       • Can last up to 20 years.
     • Disadvantages
       • May need blood thinners to prevent clotting.
       • Surgery can lead to serious injury and complications.
   • Stents
     • Advantages
       • Success rate is high.
       • Lowers the risk of heart problems/attacks.
       • Have a long lifetime.
     • Disadvantages
       • Complications can occur.
       • Arteries can sometimes re-close.
       • Drugs needed to stop blood from clotting.

3. Blood

   • Definition: A tissue consisting of plasma, red and white blood cells and platelets.
   • It transports...
     • CO2 from the organs to the lungs.
     • Soluble products of digestion from the small intestines to other organs.
     • Urea from the liver to the kidneys.
   • Red blood cells transport oxygen to the organs. They have no nucleus and are packed with a red pigment called haemoglobin. It is this substance that bonds with oxygen to form oxyhaemoglobin in the lungs.
   • White blood cells have a nucleus and are part of the immune system.
   • Platelets are fragments with no nucleus and help to clot at a wound by producing protein threads.

4. Plants

   • Xylem transport water and mineral ions from the roots to the stem and leaves.
   • The movement of water from the roots to the rest of the plant is called the transpiration stream.
   • Phloem tissue carry dissolved sugars from the leaves to the rest of the plant, including where it is growing and the storage organs.

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