IMMUNITY is covered in CSEC Biology and Human & Social Biology Syllabus. It looks at the body's line of defense and the types of immunity.

1. THE IMMUNE SYSTEM
Students should be able to:
Describe the role of the blood in defending the body
Explain how the principles of immunization are used to
control communicable disease

2. T E R M IN O L O G Y
• A N T I B I O T I C S : A drug used to treat infections
caused by bacteria and other microorganisms
(inhibits growth or destroys).
e.g. penicillin, streptomycin, tetracycline
• A N T I G E N : A toxin or other foreign substance
that induces an immune response in the body, esp.
the production of antibodies.
• A N T I B O D Y : A blood protein produced in
response to and counteracting a specific antigen

3. • I M M U N I T Y : The ability to resist a particular toxin
by the action of specific antibodies.
• I M M U N I Z A T I O N : the act of making immune
(especially by inoculation, i.e. taking a vaccine as a
precaution against contracting a disease).
• V A C C I N E : A substance used to stimulate the
production of antibodies and provide immunity against
one or several diseases, prepared from the causative
agent of a disease, its products, or a synthetic
substitute, treated to act as an antigen without
inducing the disease.

4. FIRST LINE OF DEFENSE
• Goal: to stop pathogens from entering the body
 Skin – acts as a barrier to invasion
 Sweat – has chemicals which can kill different
pathogens.
 Tears - have lysozyme which has powerful
digestive abilities that render antigens harmless.
 Saliva – also has lysozyme.
 Mucus - can trap pathogens, which are then
sneezed, coughed, washed away, or destroyed
by chemicals.
 Stomach Acid – destroys pathogens

5. SECOND LINE OF DEFENSE
• If a pathogen is able to get past the body's first
line of defense, and an infection starts, the body
can rely on it's second line of defense.
• First there is a non-specific response
(phagocytosis) followed by an INFLAMMATORY
RESPONSE.

6. • Phagocytosis =
ingestion + digestion
of pathogens.
• Phagocytic leucocytes
(macrophages) engulf
pathogens.

7. Inflammation causes:
ii.Redness - due to capillary dilation resulting in
increased blood flow
iii.Heat - due to capillary dilation resulting in
increased blood flow
iv.Swelling – due to passage of plasma from the
blood stream into the damaged tissue
v. Pain – due mainly to tissue destruction and, to
a lesser extent, swelling.

9. THIRD LINE OF DEFENSE
• Sometimes the second line of defense is still not enough
and the pathogen is then heading for the body's last line
of defense, the immune system.
• The immune system recognizes, attacks, destroys, and
remembers each pathogen that enters the body. It does
this by making specialized cells and antibodies that
render the pathogens harmless.
• Unlike the first line and second line defense the immune
system differentiates among pathogens.
• For each type of pathogen, the immune system produces
cells that are specific for that particular pathogen.

10. • The Immune System includes all
parts of the body that help in the
recognition and destruction of
foreign materials.
• Parts of the immune system:
 white blood cells(phagocytes
and lymphocytes)
 bone marrow
 lymph nodes
 tonsils
 thymus
 spleen

11. TYPES OF IMMUNITY
P A S S IV E A C T IV E
• Source: It is developed • Source: It is developed by
when ready-made an individual’s own cells in
antibodies are inoculated response to an infection or
from outside. a vaccine.
• Side effects: It may cause • Side effects: It has no side
reaction. effects.
• Period of relief: It provides • Period of relief: It provides
immediate relief. relief only after long
• Period of effectiveness: It period.
is short lived • Period of effectiveness: It
is long lasting.

12. • The natural passive immunity occurs,
when the maternal IgG type
antibodies is passed to the foetus
through the placenta. It is very much
helpful in the initial 6 months of the
infant’s life when the immune system
is still developing.
• In the artificial passive immunity, we
are introducing immunoglobulin or
pre formed animal based antibodies
(antiserum) to a non immune person.
This can be used, following exposure,
to a pathogen.

13. • It is named as naturally
acquired active immunity
because, the person develops
the full fledged infection to the
organism and later finds himself
resistant to that organism.
• In the artificial acquired active
immunity, the patient is
introduced with an organism
(usually attenuated) along with
substances to activate the
immune response.

14. DISEASES OF THE IMMUNE
SYSTEM
• HAY FEVER: is your immune system's response
FEVER
to foreign material in the air you breathe.
• Hay fever usually refers to allergies to outdoor,
airborne materials such as pollens and molds.
• A particular kind of antibody, IgE is released
causing very sensitive reaction to the allergens.
• Histamine is produced resulting sneezing,
difficulty breathing, runny nose.
• Antihistamines and inhalers relieve symptoms.

15. • ASTHMA: is a disorder that causes the airways
ASTHMA
of the lungs to swell and narrow, leading to
wheezing, shortness of breath, chest
tightness, and coughing.