Topic 11 Animal Physiology Notes
IB Biology
11.1 – Antibody Production and Vaccination
Review – 6.3 Defence against infectious disease
Primary defense against pathogens 
 Skin – sebaceous glands secrete sebum –
 Mucous membranes – secrete mucus –
Blood Clotting
You are cut  platelets aggregate  release clotting factors  thrombin  fibrinogen  fibrin
Non-specific immunity – phagocytic white blood cells engulf pathogens if they get past your skin and
mucous membranes.
Specific immunity – lymphocytes (a type of white blood cell) produces antibodies against particular
pathogens.
Antigen – any chemical that stimulates an immune response. Antibodies will bind to an
antigen on the surface of the pathogen.
Antibodies – proteins produced by lymphocytes that help the body fight the pathogen in one
of a number of ways (make a pathogen more recognizable to phagocytes so they are more readily
engulfed, or prevent viruses from docking to host cells so that they cannot enter cells).
Antibiotics – block processes that occur in prokaryotic cells but not in eukaryotic cells
 Antibiotics are chemicals that inhibits the growth of bacteria  target DNA replication,
transcription, translation, ribosome function and cell wall formation.
 Viruses cannot be treated with antibiotics because they lack a metabolism
Antibiotic resistance – some strains of bacteria have evolved with genes which confer resistance to
antibiotics.
How can we avoid antibiotic resistance??
APPLICATIONS:
Coronary thrombosis – when coronary arteries (arteries that supply the wall of the heart with oxygen
and glucose) are blocked by a blood clot. Heart becomes deprived of oxygen and nutrients. Heart
muscle cells are unable to produce sufficient ATP by aerobic respiration and contractions become
irregular and uncoordinated. Risks associated – smoking, high blood cholesterol concentration, high
blood pressure, diabetes, obesity, lack of exercise.
HIV – virus that invades and destroys helper T-cells (lymphocyte that produces antibodies). When
there is a decrease in helper t-cells, patient cannot fight off other pathogens – this leads to AIDS.
Florey and Chain’s experiments to test penicillin on bacterial infections in mice.
11.1 HL Antibody Production and Vaccination
Nature of Science: Consider the ethical implications of research: Jenner tested his vaccine for
smallpox on a child.
UNDERSTANDING STATEMENTS
 Every organism has unique molecules on the surface of their cells.
o Antigens – any foreign molecule that can trigger an immune response.
o Most antigens are proteins and very large polysaccharides.
o The surface of our own cells contains proteins and polypeptides.
o Immune systems function based on recognizing the distinction between ‘foreign’
antigens and ‘self.’
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THE IMMUNE RESPONSE…
When a pathogen invades your cells, the following happens.
B Lymphocytes are activated by T lymphocytes in mammals.
Plasma cells secrete antibodies.
Activated B cells multiply to form a clone of plasma cells and memory cells.
1. Pathogen enters your system. You have macrophages patrolling your blood stream. When
a macrophage comes into contact with pathogen, it engulfs it and the antigens of the
pathogen are displayed in the plasma membrane of the macrophages.
2. Lymphocytes called helper T cells each have an antibody-like receptor protein in their
plasma membranes, which can bind to antigens displayed by macrophages. The
matching helper T cells bind and are activated by the macrophage.
3. The activated helper T cells then bind to matching lymphocytes called B cells. The B cell is
activated.
4. Plasma cells are mature B lymphocytes that produce and secrete large numbers of
antibodies during an immune response.
5. Activated B cells divide many times by mitosis (making clones of themselves). The
generation of large numbers of plasma cells that produce one specific antibody type is
known as clonal selection.
6. Some of the clones are memory cells, which will remain long after the infection. (They are
inactive unless the pathogen is encountered again later).
 Antibodies aid in the destruction of pathogens.
Antibodies aid in the destruction of pathogens in a number of ways.
 Opsonization: They make a pathogen more recognizable to phagocytes so they are more
readily engulfed. Once bound, they can link the pathogen to phagocytes.
 Neutralization of viruses and bacteria: antibodies can prevent viruses from docking to host
cells so that they cannot enter the cells.
 Neutralization of toxins: some antibodies can bind to the toxins produced by pathogens,
preventing them from affecting susceptible cells.
 Activation of complement: collection of proteins which ultimately lead to the perforation of
the membranes of pathogens.
 Agglutination: cause sticking together of pathogens so they are prevented from entering cells
and are easier for phagocytes to ingest.
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Immunity depends on the persistence of memory cells.
o Immunity develops when the immune system is challenged by a specific antigen and
produces antibodies and memory cells in response.
o Secondary immune response is faster and stronger than a primary response.
DRAW GRAPH HERE!
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Vaccines contain antigens that trigger immunity but do not cause disease.
o Vaccine is introduced into the body (usually by injection). May contain a live
weakened version of the pathogen, or some derivative of it that contains antigens from
the pathogen. This will stimulate a primary immune response. If the actual
microorganism enters the body as a result of infection, it will be destroyed by antibodies
in a secondary immune response.
Pathogens can be species-specific although others can cross species barriers.
o Pathogens are often highly specialized with a narrow range of hosts. There are
bacterial pathogens that only cause disease in humans. (Ex: syphilis, polio, measles).
o This is due to cells of certain organisms lacking receptors for certain antigens.
o A zoonosis is a pathogen that can cross a species barrier (ex: bubonic plague, rocky
mountain spotted fever, Lyme disease, bird flu, and West Nile virus are all zoonotic
diseases.
White cells relase histamine in response to allergens.
o Mast cells are immune cells found in connective tissue that secrete histamine in
response to infection. Histamine causes the dilation of small blood vessels in the
infected area causing the vessels to become leaky  which increases the flow of fluid
containing immune components to the infected area and it allows some of the
immune components to leave the blood vessel resulting in both specific and nonspecific responses.
Histamines cause allergic symptoms
o Histamine is a contributor to a number of symptoms of allergic reactions. Histamine
plays a role in bringing on the symptoms of allergy in the nose (itching, fluid build-up,
sneezing, mucus secretion and inflammation). Anti-histamines can be taken to lessen
the effects of allergic responses.
Fusion of a tumour cell with an antibody-producing plasma cell creates a hybridoma cell.
Monoclonal antibodies are highly specific, purified antibodies that are produced by a
clone of cells, derived from a single cell. They recognize only one antigen.
o To produce the clone of cells that will make a monoclonal antibody…
1. The antigen recognized by that antibody is injected into a mouse.
2. The mouse’s immune system makes plasma B cells that are capable of
producing the desired antibody.
3. Plasma cells are removed from the spleen of the mouse.
4. B cells are fused with cancer cells called myeloma cells…these are called
hybridoma cells (cancer cells are immortal – so this ensures the B cells will live
a long time and produce a lot of antibodies).
Monoclonal antibodies are produced by hybridoma cells.
o Many hybridomas are produced from the above procedure, so the cells would be
tested and the desired cells are isolated.
o Once identified, the desired hybridoma cell is allowed to divide and form a clone.
These cells can be cultured where they will secrete huge amounts monoclonal
antibody.
 Monoclonal antibodies are used for treatment and diagnosis of diseases.
 Malaria test
 Pregnancy tests
 HIV tests
 Treatment of cancer
 Produce antibodies to inject into rabies victims.
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APPLICATIONS and SKILLS: