immunity specific non specific

Date:6/22/2021 www. qadricohs.edu.pk FB Page: Qadri College of Health Sciences, Karachi, Sindh, Pakistan. 1
QADRI COLLEGE OF HEALTH SCIENCES, KARACHI
U-3, 2 OF
“DEFENSE MECHANISMS OF THE BODY”
By: Aftab H. Abbasi
RN, DCHN, BSN, MA, LL.B
Lecturer Nursing
Qadri College of Health Sciences Karachi

“DEFENSE MECHANISM OF THE BODY”
- This unit focuses on the resistance of the
body which microorganism’s encounter
where they enter in the human body.
- This unit highlights the importance of the
resistance or defense of the body which
will help learners in understanding that
why infection occurs sometimes and not
always.

At the completion of this unit learners will
be able to:
1- Explain the role of good health in protection against the microbial
infection.
2- Define Resistance and Susceptibility.
3- Define Nonspecific Resistance.
4- Describe the role of the skin and mucous membrane in nonspecific
Resistance.
5- Explain the process of Phagocytosis.
6- Define the Specific Resistance, Innate Resistance and Immunity.
7- Explain four types of acquired Immunity.

At the completion of this unit learners will be
able to:
8- Differentiate between humoral and cell mediated immunity.
9- Define Antigens, happen and antibodies.
10- List the five classes of antibodies and their functions.
11- Explain the role of memory, tolerance and specificity in immunity.
12- Distinguish between primary and secondary immune response.
13- Define Hypersensitivity.
14- Differentiate between i.e. delayed and immediate Hypersensitivity.

Life is a threat from everything in Nature

6- What is Immune System (Immunity) ?
Immune system is a biological
structures and processes within an
organism that protects against
disease by identifying and killing
pathogens and tumor cells. It detects
a wide variety of agents, from viruses
to parasitic worms, and needs to
distinguish them from the organism's
own healthy cells and tissues in order
to function properly.

What is Immune System?
The body’s defense against disease
causing organisms, malfunctioning cells,
and foreign particles.

Immunity
The Latin term “IMMUNIS” means
EXEMPT(free), referring to protection
against foreign agents.
DEFINITION: - The integrated body system
of organs, tissues, cells & cell products
that differentiates self from non – self &
neutralizes potentially pathogenic
organisms.
(The American Heritage Stedman's Medical Dictionary)

Basic Classification of Immunity

Where is the immune system?
Cells of the immune system are:
- Distributed throughout the body in the blood,
lymph, epithelial and CT.
- Arranged in small spherical nodules (lymphoid
nodules) found in CT and inside various organs.
• Found in the mucosa of digestive (tonsils,
Peyer’s patches), respiratory, reproductive,
urinary systems are MALT (mucosa
associated lymphoid tissue.
- Organized as differently sized organs—lymphoid
organs— the lymph nodes, spleen, thymus, bone
marrow.

Immune System composed with

Functions of the Immune System
1- To protect from pathogens:
• Intracellular (e.g. viruses and some
bacteria and parasites).
• Extracellular (e.g. most bacteria, fungi and
parasites).
2- To eliminate modified or altered self.
3- Protect the host from environmental agents
such as microbes or chemicals, thereby
preserving the integrity of the body.

Effects of the Immune System
1- Beneficial:
• Protection from Invaders.
• Elimination of Altered Self.
2- Detrimental:(Harm)
• Discomfort and collateral damage
(inflammation).
• Damage to self (hypersensitivity or
autoimmunity) .

Functional Basis of Immune System
The immune system is composed of two
major subdivisions,
the innate or nonspecific immune system
and the adaptive or specific immune
system.
The innate immune system is a primary
defense mechanism against invading
organisms,
while the adaptive immune system acts
as a second line of defense.

3- Nonspecific / Innate Resistance.
First Line of Defenses:
Includes:
chemicals, Structure of
skin/other epithelia,
and mechanisms.
Cells – mainly
neutrophils and
macrophage.

First-Line Defenses /Innate / Non specific Immune System
The body's first line of defense against
pathogens uses mostly physical and
chemical barriers such as:
- 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.

First-Line Defenses / Innate / Non specific Immune System
- Saliva – also has lysozyme.
- Mucus - can trap pathogens, which are
then sneezed, coughed, washed away, or
destroyed by chemicals.
- Stomach Acid – destroys pathogens.

A non-specific response triggered by:
Inflammatory response:
- Injury.
- penetration of bacteria.
- skin, respiratory, digestive, urinary or
reproductive tract.
Two main players
- Histamine
- complement

Inflammatory response
Histamine:
- dilates local blood vessels
- increases capillary permeability
Result is redness, heat and swelling.
Heat:
- unfavorable to microorganisms
- mobilizes white blood cells (monocytes)
- raises metabolic rate of surrounding cells.
Complement:
- chemotaxsis agent
- recruits in WBC to injury site.
The Inflammatory Response:
- starts with release of histamine and other chemicals.
- ends with WBC cleaning up the debris.

Organs of Immune System
Primary Lymphoid Organs:
- Bone Marrow and Thymus
- Maturation Site
Secondary Lymphoid Organs:
- Spleen, lymph nodes,
- MALT (mucosal associated lymph tissue)
- GALT (gut associated lymph tissue)
- Trap antigen, APC, Lymphocyte Proliferation

Lymph Nodes Functions Include:
- Filtration of particles and microorganisms to
keep them out of general circulation.
- Interaction of circulating antigens in lymph
with lymphocytes to initiate immune
response.
- Activation, proliferation of B lymphocytes
and antibody production.
- Activation, proliferation of T lymphocytes.

Innate (Non-specific) Immunity
4 barriers to infection:
- Anatomic
- Physiologic
- Phagocytic
- Inflammatory

Induced Immunity
- Immunity occurs naturally by infection or is
induced by medical intervention.
- The two types of induced immunity are active
immunity and passive immunity.
- In active immunity, the individual produces
the antibodies against an antigen.
- In passive immunity, the individual is given
prepared antibodies.

Active Immunity
- After exposure to a vaccine,
which is a non-virulent
disease agent, antibodies
are produced.
- With a booster shot or
second exposure, the
antibody titer rises to a
much higher level.
- Active immunity is long-lived
because there are memory
B cells and memory T cells
that will respond to lower
doses of antigen in the body.

Passive Immunity
You don’t produce the antibodies…
- A mother will pass immunities on to her baby during pregnancy.
- These antibodies will protect the baby for a short period of time
following birth while its immune system develops.
- Lasts until antibodies die.

3- Non-Specific (Innate) Immunity
Non-Specific (Innate) Immunity:
The human immune system has two levels of
immunity:
specific and non-specific immunity.
Through non-specific immunity, also called
innate immunity,
the human body protects itself against foreign
material that is perceived to be harmful.
Microbes as small as viruses and bacteria can
be attacked, as can larger organisms such as
worms. Collectively, these organisms are called
pathogens when they cause disease in the
host.

3- Non-Specific (Innate) Immunity
All animals have innate immune defenses
against common pathogens.
These first lines of defense include outer
barriers like the skin and mucous membranes.
When pathogens breach the outer barriers, for
example through a cut in the skin or when
inhaled into the lungs, they can cause serious
harm.
Some white blood cells (phagocytes) fight
pathogens that make it past outer defenses.
A phagocyte surrounds a pathogen, takes it in,
and neutralizes it.

6- Specific Immunity / Adaptive Immunity
Specific Immunity / Adaptive Immunity:
Specific immunity is a complement to the
function of phagocytes and other elements
of the innate immune system.
In contrast to innate immunity, specific
immunity allows for a targeted response
against a specific pathogen.
Only vertebrates have specific immune
responses.

Two types of white blood cells called lymphocytes are vital to
the specific immune response. Lymphocytes are produced in
the bone marrow, and mature into one of several subtypes. The
two most common are T cells and B cells.
An antigen is a foreign material that triggers a response from T
and B cells. The human body has B and T cells specific to
millions of different antigens. We usually think of antigens as
part of microbes, but antigens can be present in other settings.
For example, if a person received a blood transfusion that did
not match his blood type, it could trigger reactions from T and B
cells.
A useful way to think of T cells and B cells is as follows:
B cells have one property that is essential. They can mature
and differentiate into plasma cells that produce a protein called
an antibody. This protein is specifically targeted to a particular
antigen.

When a properly informed B cell recognizes the
antigen it is coded to respond to, it divides and
produces many plasma cells.
The plasma cells then secrete large numbers of
antibodies, which fight specific antigens circulating
in the blood.
Regulatory T cells (also called suppressor T cells)
help to control the immune response.
They recognize when a threat has been contained
and then send out signals to stop the attack.

Immunity, (Specific & Nonspecific)

By: Aftab H. Abbasi
RN, DCHN, BSN, MA, LL.B
Lecturer Nursing
Qadri College of Health Sciences Karachi

immunity specific non specific

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