Animal Physiology by J393230

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									Animal Physiology

      Blood



               Mr G Davidson
              Components of Blood
❤On average, we have approximately 5
 litres of blood in our body.
❤It is used to carry a large variety of
 substances around the body.
❤Blood is a mixture of cells suspended in
 a fluid.



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              Components of Blood
❤The main components of blood include:
    ♥ A straw coloured liquid called plasma.
    ♥ Red blood cells.
    ♥ White blood cells.




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                  Plasma
❤Plasma contains proteins such as antibodies.
❤It also carries soluble food substances such
 as amino acids and glucose.
❤Plasma also carries other substances such as
 urea, vitamins, minerals and hormones to
 where they are needed in the body.
❤Some carbon dioxide is also carried in the
 plasma.


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              Red Blood Cells
❤Red blood cells carry oxygen.
❤They are biconcave in shape which
 increases their surface area.
❤There are approximately 5 million red
 blood cells in every 1ml of blood.




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              Red Blood Cells
❤Red blood cells contain a pigment called
 haemoglobin, which is used to carry the
 oxygen.
❤They have no nucleus to allow more
 room in the cells for the haemoglobin.
❤They are extremely small cells and also
 very flexible which allows them to pass
 through very narrow blood capillaries.

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              Red Blood Cells




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              Oxygen Transport
❤Oxygen is absorbed by the blood
 capillaries in the lungs.
❤The haemoglobin associates with the
 oxygen to make oxyhaemoglobin.
❤When the blood gets to the cells, the
 surrounding oxygen concentration is low
 and the oxyhaemoglobin disassociates
 from the oxygen.

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              Oxygen Transport

  Haemoglobin               +           Oxygen

       Disassociation                   Association
        in the body                     in the Lungs
           tissues


              Oxyhaemoglobin
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              Oxygen Transport
❤Haemoglobin is said to have a high
 affinity for oxygen when the oxygen
 concentration is high.
❤It has a low affinity for oxygen when
 the oxygen concentration is low.




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   Oxygen Disassociation Curve
              Oxygen concentration in the blood               Dropping off
                                                                 oxygen


                                                                      Picking up
                                                                        oxygen




                                                  Respiring                        Alveoli
                                                    tissue




                                                  Oxygen concentration in the surroundings

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              Body Defences
❤Another function of the blood is to
 defend the body from foreign
 organisms.
❤Organisms which cause disease, such as
 bacteria and viruses, are called
 pathogens.



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                 Body Defences
❤These pathogens have to firstly get
 through the body’s first lines of
 defence, which include:
    ♥   Skin
    ♥   Mucus
    ♥   Acid
    ♥   Tears
    ♥   Saliva

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              Body Defences
❤Once the first line of defence is
 breeched, the second line takes over.
❤This includes white blood cells.
❤These are much fewer than red blood
 cells and they also contain a nucleus.




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              Body Defences
❤There are several types of white blood
 cell which includes monocytes and
 macrophages.
❤The cells engulf and destroy any
 foreign organisms.
❤This process is called phagocytosis.



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              Body Defences
❤The bacteria is engulfed and kept in a
 vacuole.
❤There are lysosomes in the cytoplasm
 of the phagocyte which contain powerful
 digestive enzymes.
❤The lysosomes join with the vacuole
 containing the bacteria and release
 their enzymes destroying the bacteria.

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              Body Defences
❤Phagocytosis comes under the heading
 of “general immunity”.
❤It is non-specific. i.e. it protects us
 from many different bacteria.
❤We also have specific immunity which
 involves the production of antibodies.



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              Body Defences
❤Antibodies are produced by another
 type of white blood cell called
 lymphocytes.
❤An antibody is a Y-shaped molecule with
 receptor sites on 2 points of the Y.
❤The receptor sites are shaped to fit a
 specific antigen, which is a protein
 recognised by the body as foreign.

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              Body Defences




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              Body Defences




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              Body Defences
❤Once the antibody and antigen are
 locked together the foreign organism is
 rendered harmless.
❤They can now be engulfed by a
 phagocyte.




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              Body Defences
❤This type of defence is useful because
 the lymphocytes can then “remember”
 the organism and produce antibodies
 much quicker the next time it appears.
❤E.g. if you are infected by the measles
 virus, lymphocytes will begin multiplying
 and producing antibodies to fight off
 the disease.

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              Body Defences
❤You will be ill for a time but the
 antibodies will eventually destroy the
 viruses and you will recover.
❤Some of the lymphocytes, however,
 remain as memory cells, and should the
 same virus enter your body again, it will
 have the antibodies to fight it off
 before it can make you ill.
❤This is called specific immunity.
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              Body Defences
❤The first time the body is infected is
 called the primary response.
❤The second time it is infected is called
 the secondary response.
    ♥ It is more rapid than the primary response
    ♥ It produces more antibodies
    ♥ The antibodies last longer


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              Body Defences
❤There are 2 ways to gain specific
 immunity.
    ♥ Passive immunity is when a ready-made
      antibody gets into the body, e.g. through
      breast milk.
    ♥ Active immunity is when antibodies are
      made in response to disease or vaccination.



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              Body Defences
❤A vaccination is an injection of treated
 antigens which stimulate the
 lymphocytes into producing antibodies,
 but does not cause the disease.
❤This is called artificial immunity or
 immunisation.



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