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Topic 11:
Human Health and Physiology
11.1 Defense Against Infectious
Diseases
11.1.1 Describe the process of blood clotting
When human tissues and organs are
injured, so are blood vessels
The body reacts in a non-specific
response called clotting
• Non-specific – the body does not
produce substances for a specific
pathogen or disease (for example antibodies)
Equally important, it does not clot when
there isn’t an injury which would prevent
blood flow
11.1.1 Describe the process of blood clotting
The process:
Blood reacts with:
• the air
• damaged cells
• platelets
Step 1: Damaged cells and platelets
release an enzyme called thrombokinase
Step 2: The combination thrombokinase,
and clotting factors (X and VII) and Ca2+
ions will change prothrombin (inactive
form) into thrombin.
11.1.1 Describe the process of blood clotting
Step 3: Thrombin will change soluble
fibrinogen into smaller insoluble fibrin
molecules.
This forms a net that catches platelets and
erythrocytes (RBC) and forms a plug or
clot.
11.1.2 Outline the principle of challenge and response, clonal
selection and memory cells as the basis of immunity
11.1.4 Explain antibody production
• Blood contains red blood cells (erythrocytes) and white blood cells
(leukocytes).
• It is the leukocytes that play a major role in the immune system
• There are many different types of leukocytes
11.1.2 Outline the principle of challenge and response, clonal
selection and memory cells as the basis of immunity
11.1.4 Explain antibody production
Immunity – the body’s ability to recognize
self and distinguish self from non-self
substances (any non-self substance is called
an antigen)
Antibody – a special type of protein
constructed in the shape of a “Y”
The top part of the “Y” is the antigen binding
site
This binding site is what gives the antibody
its specificity
11.1.2 Outline the principle of challenge and response, clonal
selection and memory cells as the basis of immunity
11.1.4 Explain antibody production
Challenge and response” – when a pathogen invades an organism, the
organism is challenged and must respond
11.1.2 Outline the principle of challenge and response, clonal
selection and memory cells as the basis of immunity
11.1.4 Explain antibody production
Step 1: The macrophages ingests the pathogen
(phagocytosis)
Step 2: Part of the
bacterial cell wall and cell
membrane is displayed on
the outside of the
macrophage (on MHC
protein)
11.1.2 Outline the principle of challenge and response, clonal
selection and memory cells as the basis of immunity
11.1.4 Explain antibody production
Step 3: The macrophage travels to the lymph node
• The lymph node contains cells called
lymphocytes
• When the macrophage is in the lymph node it
will select a helper T- cell which has receptors
that are complimentary to the antigen that the
macrophage is carrying
Step 4: The T-cell is activated and will divide by
mitosis creating a clone
The cloned T-cells will activate B-cells which also
have surface receptors that are complementary to
the antigen.
This is called clonal selection (the process when
the macrophage selects which T-cells and B-cells
have required surface receptors)
11.1.2 Outline the principle of challenge and response, clonal
selection and memory cells as the basis of immunity
11.1.4 Explain antibody production
Step 5: B-cells also form clones.
• B-cells produce memory cells that create
a faster and stronger response to an
antigen that has infected the body
before
• B-cells also become plasma cells which
will make large amounts of antibodies
• This is called clonal expansion
Clonal expansion – is the process in which T-cell and Bcells form clones through mitosis. This results in a large
number of cells to deal with the infection.
11.1.2 Outline the principle of challenge and response, clonal
selection and memory cells as the basis of immunity
11.1.4 Explain antibody production
11.1.3 Define active and passive immunity
Active immunity – production of antibodies by the organism itself after the body's
defense mechanisms have been stimulated by antigens. This can be from a previous
infection or injection of antigens.
Passive immunity – the immunity that is due to the
acquisition of antibodies from another organism in
which active immunity has been stimulated
(placenta, colostrum, injection of antibodies)
11.1.5 Describe the production of monoclonal antibodies and
their use in diagnosis and treatment
Monoclonal antibodies can be used to determine
someone's blood type or vaccinate a patient.
They are obtained from a single B-cell clone that
is fused with an immortal tumor cell.
11.1.5 Describe the production of monoclonal antibodies and
their use in diagnosis and treatment
Example: Using Monoclonal Antibodies to
Determine Blood Type
• A mouse is injected with an antigen (for
example, human red blood cell type A)
• Mouse plasma cells will produce
antibodies in response to the human red
blood cells
• The plasma cells are extracted and fused
with B-cell tumor cells.
• These hybrid cells are grown in culture
and will produce identical antibodies
(anti-A)
• Now, if you add human blood to the
antibodies produced by the hybrid cells.
• If you see clotting than you know that the
blood sample contains type A blood.
11.1.6 Explain the principles of vaccination
Vaccination uses the same principles as memory cells in creating a fast secondary
response to an antigen.
Vaccination is the deliberate exposure of a patient to the antigens (epitopes) of a
dead or a weakened pathogen.
The patient develops memory cells against the antigen.
Recovery is therefore rapid perhaps
showing little or any sign of infection
with these serious diseases because:
• high antibody levels
• rapid response
Used for serious disease (polio, tetanus,
measles, etc...)
11.1.7 Discuss the benefits and dangers of vaccinations
Keyword
11.1.7 Discuss the benefits and dangers of vaccinations