Immunity can be defined as a complex biological system endowed with the capacity to recognize and tolerate whatever belongs to the self, and to recognize and reject what is foreign.

1. The Immune System
Prepared by
Mr.Abhay Rajpoot
HOD (Dep. of Medical Surgical)
abhayrajpoot5591@gmail.com

2. The Immune System
 The immune system is the body's natural defense against
disease-causing agents such as bacteria, viruses and parasites.
 The immune system is made up of a complex and vital network
of cells and organs that protect the body from infection.
 It plays an important role in identifying and eliminating
abnormal cells.
 The Human Immune System is divided into two broad
groups :
 Acquired Immune System
 Acquired immunity is immunity you develop over your lifetime. It
can come from: a vaccine. exposure to an infection or disease.
 Innate Immune System
 The innate immune system is made of defenses against infection
that can be activated immediately once a pathogen attacks.

3. Innate Immunity
 Resistance of skin
 Destruction of organisms by the acids in the stomach
 Chemical compounds in the blood
 Cells called
"Macrophage"that ingest foreign objects

5. Structure and organs of the Immune System
 The structures of the immune system, detailing the parts of
the body that play a role in immunity. These include:
– The lymphatics
– Lymph nodes
Lymphatic Organs and Structures
– Thymus
– Spleen
 Lymph
– A fluid containing:
 Water
 Sugars
 Salts
 Waste
 White Blood Cells
 Protein
 Lymph Vessels
– Carry lymph within the
lymphatic system
– Lymph capillaries are
the smallest of the
lymph vessels

7. network
Blood flow
Systemic capillary
network
Lymphatic
capillaries
Lymph
node
Lymphatic
vessels
Lymph
flow
Lymph
node
Lymph
flow
Lymphatic
capillaries
Pulmonary capillary
Structure and organs of the Immune
System

8. Structure and organs of the Immune
System
Lymph Nodes
 Specialized organs that produce lymphocytes.
 Filter harmful substances from the tissues.
 Contain macrophages that devour foreign substances.
 Lymphocytes produce specialized proteins called antibodies that fight
disease.
 Antigens also fight disease by stimulating an immune response in
other cells.
Lymph
 Travels in only one direction.
 Empties into the right thoracic duct and the lymphatic duct.
 Lipids are transported from the small intestines to the blood stream
by the lymph vessels.
Location of major groups of lymph nodes:
-Mediastinum
9
- Tonsils -Adenoids -Neck -Armpit -Groin

9. Structure and organs of the Immune
System
Spleen
 Largest lymphatic organ located in upper left portion of the abdominal
cavity.
 Filters foreign material from the blood.
 Destroys old red blood cells
 Activates lymphocytes
Thymus Gland
 Soft gland with two lobes
 Larger during infancy and childhood
 Contains important cells called thymocytes
 T cells (T lymphocytes provide immunity)
 Thymosin aids with T cell movement

11. Major Players
The major players in the immune system include:
– Macrophage
– T cells (helper, cytotoxic, memory)
– B cells (plasma, memory)
– Antibodies
White Blood Cells – Lymphocytes
The lymphocytes are of 2 types
• T lymphocytes
• B lymphocytes
 Higher rank officials of the immune system and have a sophisticated
mode of action.
 Their importance is highlighted by the fact, that an absence of
lymphocytes, which occurs in AIDS, leaves the body unprotected
from infections and finally leads to early death.

12. B- lymphocytes
 The B lymphocytes are present in lymph nodes.
 Upon finding the relevant antigens get activated and transform
themselves to plasma cells.
 Plasma cells secrete large quantities of antibodies
corresponding to the antigen found by the B lymphocytes.
 These antibodies circulate in blood and attach to all infecting
organisms and cells present in the body having the concerned
antigen.
T- lymphocytes
 This helps them recognize all the tissues of onesown body.
 Their response to an overwhelming infection, is in the form of
multiplication of the particular cell family concerned with
destruction of the particular foreign antigen.
 They not only destroy the antibody coated cells but also stimulate
activation and formation of plasma cells by B lymphocytes.
 The T lymphocytes are highly specialized and trained cells, which
intelligently tackle infections by recognizing and multiplication of a
specific lineage of cells, which perform higher immune functions.

13. Antibodies
 Antibodies are
assembled out of
protein chains.
 There are many different
chains that the immune system
assembles in different ways to
make different antibodies.

14. Antibodies as Receptors
 Antibodies can attach to B cells, and serve to recognize
foreign antigens.

15. Antigens as Effectors
• Free antibodies can
bind to antigens, which
“tags” the antigen for
the immune system to
attack and destroy.

16. Role of antibodies
 Antibodies released into the
blood stream will bind to the
antigens that they are specific
for.
 Antibodies may disable some
microbes, or cause them to stick
together (agglutinate).
 They “tag” microbes so that the
microbes are quickly recognized
by various white blood cells.

18. Role of Skin
Dead skin cells are
constantly sloughed
off, making it hard for
invading bacteria to
colonize.
Sweat and oils contain
anti-microbial
chemicals, including
some antibiotics.

19. Role of mucus and cilia
s
t
gs
s
Mucus contains lysozymes,
enzymes that destroy
bacterial cell walls.
The normal flow of mucus
washes bacteria and viruse
off of mucus membranes.
Cilia in the respiratory trac
move mucus out of the lun
to keep bacteria and viruse
out.
Nasal
mucosa

20. Role of phagocytes
Phagocytes are several types of
white blood cells (including
macrophages and neutrophils)
that seek and destroy invaders.
Some also destroy damaged
body cells.
Phagocytes are attracted by an
inflammatory response of
damaged cells.

21. The not-so-common cold
 A “cold” is an infection
of the mucus
membranes of the
respiratory tract by a
rhinovirus.
 Over 100 rhinoviruses
have been identified,
which is one reason
why we don'tbecome
immune to “the cold.”

22. Virus vs. Bacteria
“killed” with
antibiotics.
Rhinovirus
Colds and influenza are
caused by viruses.
Viruses are which is a
non-living particle that
contains genetic
material, and hijacks
your cells to reproduce.
Viruses cannot be
Influenza
virus

23. Virus vs. Bacteria
Bacteria are living
organisms that have a
metabolism, have
DNA, and can reproduce
on their own.
Bacteria can be killed
with antibiotics because
these substances target
key processes in
bacteria, such as
production of the
bacterial cell wall.
E. coli
Streptococcus

24. Helping the Immune System
Medical science has
created to systems for
augmenting the human
immune system:
– Antibiotics
– Vaccines

25. How antibiotics work
Antibiotics help destroy bacteria (but not viruses).
Antibiotics work in one of several ways:
– Slowing bacteria reproduction.
– Interfering with bacterial cell wall formation.

26. How vaccines work
Modern vaccines are created from killed bacteria or
viruses, or fragments of proteins from these
microbes.
The proteins are recognized as antigens by our
immune systems. This causes a mild immune
response. Memory T-cells and B-cells remain ready
to fight off the illness if it is encountered again.

27. AIDS
AIDS (Acquired Immune Deficiency Syndrome)
is caused by an infection by the HIV (Human
Immunodeficiency Virus), which attacks and
destroys T-helper cells. Because it attacks the
immune system directly, finding a vaccine has
been difficult.
Some drugs can slow down HIV reproduction,
but no cure exists yet. Prevention is still the best
“cure.”

28. AIDS
The HIV virus fools helper T-cells into
thinking its proteins are “self,” and so
is able to infect the cells that trigger
specific immunity.
The virus forces T-cells to
make more viruses, killing the
T-cells when the new viruses
burst out.

29. AIDS Prevention
HIV is a fragile virus that cannot live outside the
human body for more than a few minutes.
Preventing HIV spread comes down to preventing
exposure to body fluids of an infected person.

30. The End
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