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					Immune system and Parasitic
        infections
                          Immunology
• Study of immune response
• Immune Response
    – Protective response of the body against
        • Any agent (physical, chemical)
        • Any pathogen (bacterial, viral, fungal or parasitic)

• Very hot or very cold temperature
• Any hard/sharp object causing closed/open wounds
• Any acid or base strong enough to cause precipitation or
  liquefaction of proteins
• Bacteria causing tetanus, botulism, enterotoxaemia etc.
• Viruses causing small-pox, cow-pox, flu etc.
• Fungi
• Parasites causing malaria, sleeping sickness, surra, kalazar,
  amaoebic dysantary, elephantiasis etc.
        Living beings and Pathogens

• A continuous war for survival
• Different defense mechanisms against entry of pathogen
• Skin, one of the most important defense organs
   – Any breach in the continuity of skin fecilitates entry of
     pathogens
   – Difficult for viruses or bacteria to breach this barrier but some
     parasites have optimally adapted to breach this barrier like
     Schistosomas’ stage ready to infect intermediate hosts
• Mucous membranes
• Acidity of stomach
• Defense lines of immune system
              Immune System

[a]    Defence System
[b]    Extremely adaptable
[c]    Generates a variety of cells and molecules


            Immune Response
Two interrelated activities
[1]    Recognition

[2]    Response
                         Recognition



                    Remarkably Specific

Discriminate between foreing pathogen Distinguish one pathogen from another
      and own cells and proteins
                   Response

Also known as effector function.

Eliminate or neutralize foreign organisms.

Later exposure to same foreign organism  memory
response  heightened immune reactivity.
               Immunity

“State of protection from infectious diseases”



             Immunity

Specific (Aquired)       Nonspecific (Innate)
                          Immunity
• The body’s ability to mount a protective reaction against any physical,
   chemical or biological agent bringing about a change in homeostasis
    – Natural/Innate and Adaptive/Acquired Immunity
Innate Immunity:
       First line of defense after physical or chemical barriers crossed,
       specific to common pathogen molecules like PAMPs (PG, LPS, ssDNA,
       dsDNA, flagellin) recognised by TLRs present on surface of many
       types of cells, within few minutes to hours
Adaptive Immunity:
   a well organised and more specific response against an invader,
   specifique to unique pathogen molecules, capable of keeping a bleuprint
   (memory) to mount a rapid response against future attacks by the same
   pathogen, within few days to weeks at first encounter and very rapidly in
   the following encounters
Immune Response
                   Nonspecific Immunity
“Basic resistance to disease that a species possesses”



                          Nonspecific Immunity
                               Barriers

    Inflammatory     Endocytic or Phagocytic   Physiologic   Anatomic
              Anatomic Barriers

Skin
Sebaceous Glands  secrete sebum  low pH (3-5)
 Inhibitory to growth of most microorganisms.

Mucous membranes of the respiratory/GI/Urogenital tracts


Secrete mucus  traps microorganisms and expels them
by movement of celia.
Breach in the physical barrier:
     Wound or injection
            Physiologic Barriers

Temperature
pH

Soluble factors

Gastric juice acidic  organisms can’t survive.

Newborns  less acidic gastric juice  more susceptible
to infections.
             Physiologic Barriers


Soluble factors
Complement = serum proteins that are non active.

when pathogen enters  activated  membrane damaging
reactions  clear infections
   Endocytic and Phagocytic Barriers

Endocytosis “Macromolecules in the ECF internalized by
             cells”

Phagocytosis “More specialised and involves plasma
              membranes expanding around
              macromolecules”

Specialized phagocytic cells include: monocytes,
                                      macrophages and
                                      neutrophils.
            Inflammatory Response
 Signs

 Redness
 Swelling
 Heat
 Pain

Three major events

(1) Vasodilation
(2) Increased capillary permeability
(3) Influx of phagocytic cells (chemotaxis)
Barriers of innate immunity
Summary
Summary

				
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Description: immunity development.pdf