aquired immunity
TRANSCRIPT
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AQUIRED IMMUNITY
(Adaptive or Specific)
Husan BanoAssociate professor
Department PhysiologyAl-Tibri Medical College
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REVIEW OF PREVIOUSLECTURE
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As microorganism enter into
body our first line of defenseactivated.
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First line of defense
(Innate Immune)
Body uses physical and chemical barriersagainst infection such as:
Skin prevent entry of microorganism. Sweat Itschemicals kills pathogens.
Tears - have lysozyme which digest forigen
body. Saliva also has lysozyme. Mucus - trap pathogens. Stomach Acid destroys pathogens
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Second Line of Defense(Innate Immune)
If first line of defense is weak, thepathogen enter into the body and an
infection starts.
Now the bodys second line of defenseactivated. This is called an Inflammatoryresponse.
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Inflammatory response.
Redness - due to capillary dilation andincreased blood flow .
Heat - due to capillary dilation resulting inincreased blood flow
Swellingdue to flow of plasma into the
damaged tissue
Pain due to tissue destruction .
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Third Line of Defense
(Acquired immunity)
If the second line of defense is not enough
the body's Third-Line Defenseor immunesystem activated.
The immunity which is caused by immunesystem is called Acquired immunity
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Acquired immunity
Acquired immunityare of 2 types:
1. Cell mediated immunity or T-cell immunity
2. Humoral Immunity or B- cell immunity
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Acquired Immunity
Lymphocytes play an important role inacquired immunity. (Both cell mediated andhumoral type).
Lymphocytes formed from bone marrow fromstem cell. These are called BasicLymphocytes.
They mainly located in lymph nodes.
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Acquired Immunity Cont.
Besides bone marrow, They are alsoformed from lymphoid organs.
In lymphoid tissue, the lymphocytes aremainly of two types.
1. T- lymphocytes2. B- lymphocytes
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Acquired Immunity Cont.
Those basic lymphocytes which enter into
thymus for preprocessingor activation, calledT- Lymphocytes.
These are responsible for Cell-mediatedimmunity.
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Acquired Immunity Cont.
On the other hand, those basiclymphocytes which enter into liver for
activation in foetal life or other bursalequivalent organ in adult life, are called
B- lymphocytes
These are responsible for Humoralimmunity.
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1. Cell mediated or T-cell immunity.
It is mediated by T-lymphocytes
T-lymphocytes recognize foreign body bymeans of surface receptors
T-lymphocytes attack and destroy foreignmaterial directly or through release of
soluble mediators i.e. cytokines
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T-cells Ag Macrophageconverted into
lymphoblast
converted intoTremendous activated T cells memory cells
Lymphoid organs
Via lymph enter into circulation
Activated T- cellcirculation
Cytotoxic
T- cell
Supressor
cells
Helper
T-cell
DestructionOf
Antigens
Causes Directly
ActivationOf
OtherImmune response
Secretes
lymphokinaseA
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2. Humoral immunity Or(B- cell immunity)
B-lymphocytesare responsible forhumoral immunity.
B- lymphocytes produces Plasma Cells.
Plasma cells produced antibodies.
These have the ability to recognize andbind to antigen.
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Humoral immunity Or(B- cell immunity)
B- lymphocytes first discover in bird in anorgan called Bursa fibricus.( This is the
lymphoid organ associated with GIT.
In human being several bursal equivalent
organs are present such as spleen ,lymphnode, tonsil etc.
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Mechanism Of Humoral orB- cell immunity:
Stem cellB- lymphocytesBone Marrow
Basic lymphocytesCirculation
Activation, maturation of B-lymphocytesBursal equivalent
organs
Release B- lymphocytesCirculation
Goes to areas of B-cell in lymphoid organsLymph node
Spleen
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Mechanism Of Humoral orB- cell immunity:
Lymph node B- cell areas
( B- lymphocytes)
Plasma blasts
Lymph nodeSpleen
Plasma cells
Anti bodies
Memorycells
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Mechanism Of Humoral orB- cell immunity:
Ab + Ag complex
neutrilization Opsonization Complement activation Destroy antigen
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Active Immunity
Active immunity occurs when one makeshis/her own antibodies.
This type of immunity is long term.
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Passive Immunity
Passive immunity occurs when theantibodies come from some other source.
This type of immunity is short term. e.g
breast milk by whichbaby gain passiveimmunity
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Vaccination:
A vaccination is an injection of a weakestform of the actual antigen that causes the
disease.
The injection is so weak that person notbecome sick, but his B lymphocytes will
recognize the antigen, and produceMEMORY cells for long term immunity
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