Body defense immunity & immunization

Body defence
immunity & Immunization
Mr. Melvin Jacob
MSc Nursing
111-11-2020 Mr.Melvin Jacob MSc (N)

INTRODUCTION
The environment contains a wide variety of
potentially harmful organisms (pathogens), such as
bacteria, viruses, fungi, protozoa and multi cellular
parasites, which will cause disease if they enter the
body and are allowed to multiply. The body
protects itself through a various defence
mechanisms to physically prevent pathogens from
entering the body or to kill them if they do.

IMMUNITY
• The term immunity refers to the body’s
specific protective response to an invading
foreign agent or organism.
• 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.

TYPES OF IMMUNITY
1. Natural (Innate) immunity
2. Acquired (adaptive) immunity

I. Natural immunity
• It is a nonspecific immunity present at birth
• It is the ability to distinguish between friend and foe or
self and non-self.
Such natural mechanisms include
1. Physical and chemical barriers
– Skin and mucous membrane
– Antimicrobial substance in body secretions
2. The action of WBCs
3. Inflammatory response.

Physical and chemical barriers
Skin and mucous membrane
• Intact skin & mucous membrane - physical barrier to
invading microbes.
• Sebum and sweat secretion - contains antibacterial
and antifungal substances
• Hairs in the nose acts as a coarse filter.
• One way flow of urine from the bladder during
micturation

Antimicrobial substance in body
secretions
1. Hydrochloric acid in gastric juice
2. Lysosomes
3. Saliva
4. Immunoglobulin in nasal secretions and saliva
(IgG, IgA, IgM, IgD and IgE, which have a range of
functions.)

Inflammatory response
• Major function of the natural 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

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

II. Acquired immunity
• Usually develops as a result of prior exposure
to an antigen through immunization or by
contracting 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.

Active and passive 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

Types of immunoglobulin

IgG
IgG (75% of total immunoglobulin)
• Appears in serum and tissues (interstitial fluid)
• Assumes a major role in blood borne and tissue
infections.
• Activates the complement system.
• Crosses the placenta

IgA
IgA (15% of total immunoglobulins)
• Appears in body fluids (blood, saliva, tears, breast
milk, and pulmonary, gastrointestinal, and vaginal
secretions).
• Protection against respiratory, gastrointestinal
and genitourinary infections.
• Prevents absorption of antigens from food.
• Passes to neonate in breast milk for protection

IgM
IgM (10% of total immunoglobulins)
• Appears mostly in intravascular serum
• Appears as the first immunoglobulin produced
in response to bacterial and viral infections.
• Activates the complement system.

IgD
IgD (0.2% of immunoglobulins)
• Appears in small amounts in serum
• Possibly influences B-lymphocytes differentiation,
but role is unclear.
IgE
IgE (0.004% of immunoglobulins)
• Appears in serum
• Takes part in allergic and hypersensitivity of
reactions
• Combats parasitic infections. 1611-11-2020 Mr.Melvin Jacob MSc (N)

Line of defence
• Prevents infection through a number of non-specific
and specific mechanisms working on their own or
together.
• First lines of defence are external barriers that
prevent germs from entering.
• Skin which acts as a strong, waterproof, physical
barrier and very few organisms are able to
penetrate undamaged skin.

• Skin - a strong physical barrier, like a waterproof
wall
• Mucus – a sticky trap secreted by all the surfaces
inside the body that are directly linked to the
outside, also contains antibodies and enzymes
• Cilia – microscopic hairs in the airways that move
to pass debris and mucus up away from the lungs

• Lysozyme – a chemical (enzyme) present in
tears and mucus that damages bacteria
• Acid - in stomach and urine, make it hard for
any germs to survive
• Fever – elevated body temperature making
conditions unfavourable for pathogens to
survive

Immunization
• Immunization is the process whereby a person is
made immune or resistant to an infectious
disease, typically by the administration of a
vaccine.
• Vaccines stimulate the body’s own immune
system to protect the person against subsequent
infection or disease.

• Protect us from serious diseases
• Prevent the spread of those diseases
• Epidemics of once common infectious
diseases such as measles, mumps,
and whooping cough.

The recommended immunizations for
children 0-6 years of age
• Hepatitis B
• Rotavirus
• Diphtheria, tetanus, pertu
ssis (DPT)
• Haemophilus
influenzae type B
• Pneumococcal
• Poliovirus
• Influenza
• Measles, mumps, rubella
• Varicella (chickenpox)
• Hepatitis A
• Meningococcal (for
certain high-risk groups)

Reference
• Dougherty L, Lister S (2015) The Royal
Marsden Hospital Manual of Clinical Nursing
Procedures. Oxford: Blackwell.
• Helen Harkreader. Fundamentals of nursing
caring and clinical judgement. Elsevier
publication St. Louis: 2009;(3).

Body defense immunity & immunization

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