The document provides an overview of the immune system, detailing various types of immunity including natural and acquired immunity, and their mechanisms of action against foreign substances like bacteria and viruses. It explains the roles of antibodies, antigens, and different types of cells involved in both humoral and cell-mediated immune responses. Additionally, the document discusses the concept of herd immunity and its significance in protecting populations from diseases.

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4.  Immunity definition - “Reaction of the body
towards any foreign substance or non self”.
 The immune response is how your body
recognizes and defends itself against bacteria,
viruses and substances that appear foreign and
harmful to the body.
 Immune mechanism reacts with every foreign
substance whether visible or microscopic.
 Host defense(Immunity) may be
1. Natural Immunity
2. Acquired Immunity

5. Local
Systemic
Active
Specific
Passive
Non-specific
Humoral
Cellular
1. Humoral
2. Cellular
3. Combination

6.  Immune system includes barriers.
 These barriers are innate immunity, (with you
from birth) skin, stomach acid, mucus (which
traps bacteria and small particles), the cough
reflex, and enzymes in tears and skin oils.
 If an antigen gets passed the external barriers,
it is attacked and destroyed by other parts of
the immune system.
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7. Blood components
 The immune system includes certain types of
white blood cells.
 It also includes chemicals and proteins in the
blood, such as complement proteins and
interferon.
 Some of these directly attack foreign
substances in the body, and others work
together to help the immune system cells.
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8. Inflammation
 The inflammatory response (inflammation)
occurs when tissues are injured by bacteria,
trauma, toxins, heat, or any other cause.
 Chemicals including histamine, bradykinin,
serotonin, and others are released by
damaged tissue.
 These chemicals cause blood vessels to leak
fluid into the tissues, causing swelling.
 This helps isolate the foreign substance
from further contact with body tissues.

9.  Definition - “An antigen is a substance
which when introduced into the body
stimulates specific immune response”.
 Chemically an antigen may be a
protein, carbohydrate, lipid or nucleic
acid and usually foreign or non self to
the body.

10.  Definition - “An antibody is a protein
substance produced in response to a
specific antigen with which it combines
chemically”.
 This reaction of antibody results in
neutralization and elimination of antigen.

11. IMMUNITY
NATURAL/ INNATE
IMMUNITY
Racial
Species
Individual
Acquired
Immunity
Active
Acquired
Natural
Active
Acquired
Artificial
Active
Acquired
Passive
Acquired
Natural
passive
Acquired
Artificial
passive
Acquired

12. Innate or Natural
immunity

13.  Immunity which may be genetically passed
from one generation to another .
 Types of innate immunity –
1. Species innate immunity
2. Racial innate immunity
3. Individual innate immunity

14. 1. Species innate immunity –
 Resistance to pathogen, shown by all
members of a particular species.
 Ex. Anthrax bacilli present in soil.
 Anthrax infects human because absence of
immunity against anthrax.
 Chickens - immunity present against
anthrax.
 Ex. Rats, mice and dog against tuberculosis

15. 2. Racial innate Immunity –
 Resistance towards micro-organism
among races of species.
 Ex. American Negros are more
susceptible to tuberculosis than American
white.
 American Nigros – 80%TB cases
 AmericanWhite – 20%TB cases
 E.g. Genetic resistance Plasmodium
falciparum malaria resistance in Africa
 Ex. Negro's to yellow fever.

16. 3. Individual innate immunity
 Resistance to infection varies with
different individuals of same race and
species.
 E.x. Adult – more immunity
Children and old - less immunity

17. Acquired Immunity

19.  Resistance acquired by individual during
life (birth to death)
 It may be active and passive.

20. It is the immunity which when one individual
develops as a result of infection or by specific
immunization.
a. Natural active immunity
Through clinical or subclinical infection or
disease.
b. Artificial active immunity
Obtained by vaccination ex. BCG, measles
vaccine.

21.  It develops as a result of infection or by
specific immunization.
 It is associated with presence of antibodies
or cells having specific action on micro
organism or its toxin.
 It depends on humoral & cellular response of
the host.
 Immunity produced is specific for particular
disease or organism.

22. Active Immunity acquired by three ways -
1. Following Clinical infections
Ex. Chickenpox, rubella and measles
2. Following Sub-clinical or in-apparent infection
Ex. Polio and diphtheria
3. Following Immunization with an antigen
Ex. Live or killed vaccine

23. a. Primary immune response
 An antigen is administered for the first time.
 After 3-10 days antibodies appear in the blood.
 The first antibody appeared is IgM which rises
steadily for 2-3 days reaches to peak and
then declines as fast as it developed.
 If the antigenic stimulus was sufficient, IgG
antibody appears in a few days
 IgG reaches to peak in7-10 days and falls over a
period of weeks or months.

24. Outcome of primary response -
1. Education of reticulo- endothelial system
of the body.
2. Production of memory cells or primed
cells by by B &T lymphocytes.
3. Memory cells are responsible for
immunological memory, which becomes
established after immunization .

25. Response to the booster dose differs from
primary response in following ways -
 Shorter latent period.
 Production of antibody more rapid.
 Antibody more abundant.
 Antibody response maintained at higher
levels for a longer period.
 The antibody have greater capacity to
bind the antigen.

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27.  .
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28.  Comes from the B cells (bone marrow
derived lymphocytes) which proliferate
and manufactures specific antibodies.
 The antibodies are localized in the
immunoglobulin fraction of serum.
 Immunoglobulins are divided into 5
main classes IgG, IgM,IgA,IgD and IgE
(and subclasses within them) – each
class representing a different functional
group.

29.  These antibodies circulates in the body
and neutralizes microbs or its toxin or
rendering microbe susceptible to attack by
polymorph onuclear leucocyte and
monocyte.
 Antibodies are necessary for phagocytosis
of bacteria.
 Antibodies are specific, i.e. they react with
same antigen pathogen i.e. specificity.

30.  Definition – Cell mediated immunity is
defined as the immunity developed by cell-
mediated response.
 It is also called as cellular immunity or T –cell
immunity.
 It involves several types of cells such as T
lymphocytes, macrophages, and natural killer
cells and hence the name is cell mediated
immunity.
 This immunity does not involves antibodies.

31.  Is achieved by theT lymphocytes.
 Infectious disease like M.TB, M.Leprae,
S.typhi, Candida albicans and many viruses
escape from the Humoral response.
 Cellular immunity provides protection
against such diseases.

33.  Definition - When antibodies produced in
one body (human or animal) are transferred
to another to induce protection against
disease.
 Body does not produce its own antibodies
but depends on ready-made antibodies.

34. a. Natural passive immunity
Vertical transmission through placenta (IgG)
By breast feeding – IgA at birth
b. Artificial passive immunity
Obtained by readymade immunoglobulines and
antitoxin

35. Passive immunity may be induced by –
1. By administration of an antibody-containing
preparation (immune globuline or
antiserum)
2. By transfer of material antibodies across
the placenta (human milk – IgA)
3. By transfer of lymphocytes – to induce
passive cellular immunity (still
experimental)

39.  “It is the level of resistance of a community
or group of people to a particular disease”.
 Herd immunity implies group protection
beyond that afforded by the protection of
immunized individuals.
 An epidemic declines before the whole
population becomes immune.
 If two third population in a community
becomes immune, the remaining one third
become immune.

40. The elements which contribute to herd
immunity are -
a. Occurrence of clinical and sub clinical
infection in the herd.
b. Immunization of the herd.
c. Herd structure (Birth, death and
population mobility).

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