its a little add to understand IMMUNITY in the field of physiology

1. Dr: Muhammad Muqeem Mangi
MBBS, MPhil. Physiology
Associate Professor
Suleman Roshan Medical College
Tando Adam
By

2. Introduction The human body has the ability to
resist almost all types of organisms or toxins that tend to
damage the tissues and organs. The capability is called
immunity.
Immunity is the ability of the body to protect against
all types of foreign bodies like bacteria, virus, toxic
substances etc. which enter thebody.
DEFINITION: - Theintegrated body system of organs,
tissues, cells & cell products that differentiates self
from non – self & neutralizes potentiallypathogenic
organisms.
(TheAmericanHeritage Stedman's MedicalDictionary)
1.Protection against infectious diseases
2.Distinguishes self from non-self
3.Eliminate potentially destructive foreign substances from body

3. Types

4. Acquired immunity
1. Specific immunity
develops after
birth
2. Increases in intensity
with repeated
exposure to the
invading agent.
Natural immunity
1. Is a nonspecific
immunity present at
birth
2. responses to
• invader are very similar
from one encounter to
the next.
Natural and Acquired immunity

5. It is also called natural or native immunity, consist of mechanisms that exist before
infection and are capable of rapid responses to microbes.
It is comprises four types of defense barriers-
1) Anatomical barriers
2) Phagocytic barriers
3) Blood proteins and
4) Cytokines. or
1.Physical and chemical barriers Skin and mucous membrane
2.Antimicrobial substance in body secretions
3.The action of WBCs.
4.Inflammatory response
The natural defense mechanisms is the ability to distinguish between
Innate Immunity

6. It is of three types-
1) Species Immunity
2) Racial Immunity
3) Individual Immunity
 Species immunity is the total immunity shown by all
members of a species against pathogen; e.g. birds
immune to tetanus.
 Racial immunity is that in which various races show
marked difference in their resistance to certain infectious
disease.
 Individual immunity is very specific for each and every
individual despite having same racial background and
opportunity forexposure.
Types of innate immunity

7. Physical and chemical barriers Skin and mucous membrane
• When skin and mucous membrane are intact
and healthy, they provide a physical barrier to
invading microbes.
• Sebum and sweat secreted on to the skin
surface contains antibacterial and antifungal
substances.
• Hairs in nose acts as a course filter
• One way flow of urine from the bladder
during micturition

8. 1. Hydrochloric acid in gastric juice
2. Lysosomes
3. Saliva
4. Immunoglobulin in nasal secretions and saliva
5. Interferons
Antimicrobial substance in body secretions

9. • WBCs participate in both the natural and the
acquired immune responses.
• Granulocytes include neutrophils, eosinophils
and basophils.
• Nongranular leucocytes include monocytes or
macrophages and lymphocytes.
• Lymphocytes consisting of B cells and T cells,
play major role in humoral and cell mediated
• Immune responses
White blood cell action

10. • Major function of the natural (non specific or innate)
immune system.
• Chemical mediators assist this response by
minimizing blood loss, walling off the invading
organism, activating phagocytes and promoting
formation of fibrous scar tissue and regeneration of
injured tissue
Inflammatory response

11. Type Mechanism
 Skin
 Mucous membrane
 Temperature
 Low pH
3) Phagocyticbarriers
NKcells)
4) Inflammatorybarriers
1)Anatomical barriers
Mechanical barriers retards entry of
microbes.
Acidic environment (pH 3-5) retards growth
of microbes.
Mucous entraps foreign microorganism.
2) Physiologic barriers
Body temperature and fever response
inhibits growth of some pathogens.
Acidic pH of stomach (pH 2) kills most ingested
microorganism.
Ingest and destroys microbes by
(Neutrophils, Macrophages and endocytosis and phagocytosis)
Tissue damage and infection induce leakage of
vascular fluid, containing serum protein with
antibacterial activity.

12. • Immunodeficiency
• Persistent inflammatory response
• Autoimmune bodies
Dysfunction of the natural immune system

13. Acquired or adaptive immunity is the immunity that is
developed by the host in its body after exposure to suitable
antigen or after transfer of antibodies or lymphocyte from an
immune donor.
Characteristics of Acquired Immunity
1. Antigenic Specificity
2. Diversity
3. Immunologic memory
4. Self/non-self recognition
Acquired Immunity

14. Acquired Immunity is of two types- active and passive
immunity.
1. Active immunity
It is induced by natural exposure to a pathogen or by
vaccination.
It can be categorized into two types-
Naturally acquired and Artificially acquired active immunity.
2. Passive immunity
Passive immunity is achieve by transfer of immune products,
such as antibody or sensitized T-cells, from an immune
individual to non immune one.
It is of two types- Naturally acquired and Artificially
acquired passive immunity
Types of Acquired Immunity

15. • Usually develops as a result of prior exposure to an
antigen through immunization or by contacting a
disease.
• Weeks or months after exposure to the disease or
vaccine, the body produces an immune response that
is sufficient to defend against the disease upon re-
exposure to it.
Acquired immunity
1. Active immunity: Active immunity means that the individual
has responded to an antigen and produced his own antibodies,
lymphocytes are activated and the memory cells formed
provide long lasting resistance.
2. Passive immunity: In passive immunity the individual is given
antibodies produced by someone else

16. Response to invasion
When thebody is invaded or attacked by
bacteria, viruses,or other pathogens, it has three
means of defending itself
1. The phagocytic immune response
2. The humoral or antibody immune response
3. The cellular immune response
• The first line of defense
Involves the WBCs (granulocytes and macrophages),
which have the ability to ingest foreign particles.
Phagocytes also remove the body’s own dying or dead
cells.
Phagocyte immune response

18. Humoral and cellular immune response
• A second response, the humoral
(sometimes
immune
antibodyresponse
response), begins with
called the
the B lymphocytes,
which can transform themselves into plasma
cells that manufacture antibodies.
• The third mechanism of defense, the cellular
lymphocytes, which
immune response, also involves the T
can turn into special
cytotoxic (or Killer) T cells that can attack the
pathogens themselves.

19. 1. Before exposure to a specific antigen, the clones of B
lymphocytes remain dormant in the lymphoid tissue.
2. On entry of a foreign antigen, macrophages in the
lymphoid tissue phagocytize the antigen and then
present it to adjacent B lymphocytes.
3. In addition, the antigen is presented to T cells at the
same time, and activated helper T cells are formed.
4. Those B lymphocytes specific for the antigen
immediately enlarge and take on the appearance of
lymphoblasts.
Humoral immune response

21. Humoral immune response cont…
5. Some of the lymphoblasts further differentiate to form
plasmablasts, which are precursor of plasma cells.
6. The mature plasma cells then produces gamma
globulin antibodies.
into B-
for the
7. Other B lymphocytes differentiate
lymphocyte clones with a memory
antigen.

24. Formation of antibodies and sensitized lymphocytes by a lymph node in
response to antigens. This figure also shows the origin of thymic (T) and bursal
(B) lymphocytes that respectively are responsible for the cell-mediated and
humoral immune processes

25. An antigen activates only
the lymphocytes that have
cell surface receptors that
are complementary and
recognize a specific
antigen. Millions of
different clones of
lymphocytes exist (shown
as B1, B2, and B3).
When the lymphocyte
clone (B2 in this example)
is activated by its antigen,
it reproduces to form large
numbers of duplicate
lymphocytes, which then
secrete antibodies.

28. Binding of antigen molecules to one another by bivalent antibodies.

39. Cascade of reactions during activation of the classic pathway of
complement.