A precise description of immune system.Hope it will be helpful.

1. P R E S E N T E D B Y : H I R A I F T I K H A R
R O L L N O : 3 3 2
Q U E E N M A R Y C O L L E G E
P R E S E N T E D T O : M A M A S M A
The Immune System

2. What is the
immune
system?
• The body’s defense
against disease
causing organisms,
malfunctioning cells,
and foreign particles.
• A functional system –
NOT an organ system.

3. Effectiveness
of immune
system
It must be able to
distinguish between its
own cells of body and
foreign reagents that can
bring harm to body.it can
be done in two ways:
I. The cells of body
contains unique
macromolecules on
them.These
biomolecules help
immune cells to
recognize its own
cells.
II. Pathogens have their
own membrane
bounded
biomolecules which
stimulates immune
system.

4. Components of Immune System
Complex system – includes
 Skin – physical barrier
 Lining of mucus membranes – physical barrier
 Secretions – tears, mucus etc. - antimicrobial
 Blood cells and vasculature – WBCs
 Bone marrow
 Liver – makes complement proteins
 Lymphatic system and lymphoid organs
 Most tissues – have resident immune cells

6. Nonspecific defense: the
innate immune system
T H E H U M A N B O D Y H A S A S E R I E S O F
N O N S P E C I F I C D E F E N S E S T H A T M A K E U P
T H E I N N A T E I M M U N E S Y S T E M . T H E S E
D E F E N S E S A R E N O T D I R E C T E D A G A I N S T A N Y
O N E P A T H O G E N B U T I N S T E A D , P R O V I D E A
G U A R D A G A I N S T A L L I N F E C T I O N .

7. First
line of
defense
SKIN
SALIVA,TEARS
AND SWEAT
MUCUS AND
CILIA
HCL IN
STOMACH

8. SKIN
Anatomical Barrier
• The dead, outer
layer of skin, known
as the epidermis,
forms a shield
against invaders and
secretes chemicals
that kill potential
invaders .

9. MUCUS AND
CILIA
• As you breathe in,
foreign particles and
bacteria bump into
mucus throughout
your respiratory
system and become
stuck
• Hair-like structures
called cilia sweep
this mucus into the
throat for coughing
or swallowing

10. SALIVA/TEAR
S/SWEAT
What’s the first
thing you do when
you cut your finger?
• Saliva/Tears
contains many
chemicals like
lysozymes that
break down
bacteria.
• Thousands of
different types of
bacteria can survive
these chemicals,
however.

11. STOMACH
ACID(HCL)
• Swallowed bacteria
are broken down by
incredibly strong
acids in the stomach
that break down
your food
• The stomach must
produce a coating of
special mucus or this
acid would eat
through the
stomach!

12. Think of the human body as a
hollow plastic tube…
Tube inner
surface
~Digestive
System~
Tube outer
surface ~Skin~
Plastic interior
~Body~

13. ANSWER??????
Escherichi
a coli
is common
and
plentiful in
all of our
digestive
tracts. Why
are we all
not sick?

14. INTERNAL
DEFENSE
(2ND LINE OF
DEFENSE)
Inflammatory
response
Complement
system
• Phagocytes
• Macrophages
• Mast cells
• Neutrophils
• Eosinophils
• Basophils
• Natural killer cells
• Dendritic cells
• Phagocytosis
• Inflammation
• Membrane attack

15. • These cells primarily attack bacteria.
• They rush to the site of incoming bacteria to fight them, but are easily killed.
Phagocytes
• Macrophage means ‘big eater’. These cells ‘eat’ (ingest) or clean up the mess of dead cells.
Macrophages
• Mast cells are found in mucous membranes and connective tissues, and are important for
wound healing and defense against pathogens via the inflammatory response.
Mast cells
• These granules are very toxic to bacteria and fungi, and cause them to stop proliferating or
die on contact.
Neutrophils
• Eosinophils secrete a range of highly toxic proteins and free radicals that kill bacteria and
parasites.
Eosinophils
• Basophils release histamine, much like mast cells. The use of histamine makes basophils and
mast cells key players in mounting an allergic response.
Basophils

16. • Natural Killer cells (NK cells), do not attack pathogens directly. Instead,
natural killer cells destroy infected host cells in order to stop the spread of
an infection.
Natural killer cells
• Dendritic cells are antigen-presenting cells that are located in tissues, and
can contact external environments through the skin, the inner mucosal
lining of the nose, lungs, stomach, and intestines. Since dendritic cells are
located in tissues that are common points for initial infection, they can
identify threats and act as messengers for the rest of the immune system by
antigen presentation. Dendritic cells also act as bridge between the innate
immune system and the adaptive immune system
Dendritic cells

17. THE COMPLEMENT SYSTEM
 The complement system (also called the complement
cascade) is a mechanism that complements other
aspects of the immune response. Typically, the
complement system acts as a part of the innate
immune system, but it can work with the adaptive
immune system if necessary.
 The complement system is made of a variety of
proteins that, when inactive, circulate in the blood.
When activated, these proteins come together to
initiate the complement cascade.

18. Complement
proteins : Role
in innate
immune
system
Phagocytosis –
by opsonizing antigens.
C3b has most important
opsonizing activity
Membrane attack –
by rupturing cell wall of
bacteria
Inflammation – by
attracting macrophages
and neutrophils Facilitates
phagocytosis
Direct lysis of
pathogens
Inflammation

19. Adaptive
immune
system
T cells
Cell
mediated
immunity
B cells
Hummoral
immunity

20. ADAPTIVE IMMUNE SYSTEM(SPECIFIC
RESPONSE/AQUIRED IMMUNE SYSTEM)
• The adaptive immune system, also known as the acquired
immune system or, more rarely, as the specific immune
system, is a subsystem of the overall immune system that is
composed of highly specialized, systemic cells and processes
that eliminate pathogens or prevent their growth.
• Acquired immunity creates immunological memory after an
initial response to a specific pathogen, and leads to an
enhanced response to subsequent encounters with that
pathogen.
• Both B cells and T cells are lymphocytes that are derived from
specific types of stem cells, called multi-potent hematopoietic
stem cells, in the bone marrow. After they are made in the
bone marrow, they need to mature and become activated.
Each type of cell follows different paths to their final, mature
forms.

21. Cell Mediated Immunity
 The cell mediated immunity is facilitated by
activated TH cells (T helper cells) and Cytotoxic T
lymphocytes(CTLs).
 Cytokinins activated by TH cells activate the
phagocytic cells.
 These activated phagocytic cells then phagocytosis
and kill the microbes.
 The cell mediated immunity is particularly important
against bacteria and pathogens.

22. Humoral Immunity
(antibody mediated immunity)
 It is mediated through antibodies.
 Antibodies are produced by B cells.
 The antibodies bind to specific microbial antigens.
 Binding of antibodies to antigens neutrilize microbes
and eliminate them.
 Major defense mechanism against extracellular
response.

25. Some Interesting Facts About Immunity
 Immunity refers to the total resistance of a pathogen
by all members of a specie.
 Homozygous twins exhibit similar resistance.
 Innate immunity can only be affected in placenta
majorly.