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immunity & reticuloendothelial system/ mononuclear phagocyte system
immunity
& reticuloendothelial system/
mononuclear phagocyte system
intro
immunity
is defined as the capacity of the
body to resist pathogenic agents
immunology
study of the physiological mechanisms
that humans use to defend their bodies from
invasion by other organisms
the lymphatic system or immune system are terms used for this
the immune sytem consists of a
network of lymphatic organs
tissues
& cells.
these structures are supported by the reticuloendothelial system- loose connective tissue with a network of
reticular fibers
phagocytic cells ,including
monocytes & macrophages
are located in the reticular connective tissue
the process
when micro organisms or antigens Ag invade the body
Ag are transported to the lymph
lymph is carried thru the lymph vessels to the
regional lymph nodes
in the lymph nodes-
the macrophages & dendritic cells
phagocytose antigen Ag
process them
& present the Ag to lymphocytes
lymphocytes then start producing antibodies Ab
or serve as memory cells
(their function is to recognize that specific antigenAg in the future
immunity types
innate
innate-mechanical defence
1.skin & epidermis
form partition betw body & external environment
2.mucus membrane
in body cavities
mucus secreted traps microorganisms
eg RT.GIT
3.hairs
filter n trap
eg.cilia in upper RT filters microbes
4.body secretions
like tears & saliva washes microbes away
5.excretory processes
like urination & defecation removes pathogens & toxins
frm the body
innate- chamical defense
1.acidic pH of skin
eg.bacteriacidal subs of sebum
2.chemicals in body secretions
lysozome in saliva,tears,sweat
3.acidic pH os stomach & vagina
4.complement protein
facilitate opsonization & phagocytosis
5.interferons
kills virus
innate-defenses by NK cells
are small population of large
granular lymphocytes 15%
not phagocytic
attack is by
1.
release of perforins
-perforate plasma membrane of target cells
& disintergrates it
2.
relese interferons
signaling proteins released by host cells in the presence of several viruses. In a typical scenario, a virus-infected cell will release interferons causing nearby cells to heighten their anti-viral defenses.
3.
release chemicals that enhance the inflammatory response
iinate- defence thru inflammation
inflammation
- defensive response of the body
against tissue injury
is triggered by
-injury
trauma,heat,chemical irritation,infection etc
signs of inflammation
rubor (redness
dolor (pain
calor (heat
tumor (swelling
loss of function
benefits of inflammation
-prevents spread of injury
-disposes of cellular debris & pathogens
-promotes repair
innate- phagocytes
-macrophages
derived frm monocytes
-
free macrophage
s-roam thru tissues
-fixed macrophages
-
in liver-kupffer cells
in brain- microglia
in lungs-alveolar macrophages
both types
locate ,engulf & destroy microbes
(phagocytosis
mechanism of phagocytosis
1.microbes adheres to phagocytes
2.phagocyte forms pseudopods that engulf the particle
3.phagocytic vesicle is formed,& this vesicle is fused with
a lysosome
4.microbe in fused vesicle is killed & diagested by lysosomal
enzymes within the phagolysosome
leaving a residual body
5.indiagestible & residual material is removed by exocytosis
adaptive/
aquired
humoral immunity (B lympocytes
& cell mediated immune response
(T lymphocytes
on entry of foreign antigen
macrophage engulf them
processing of antigen & present them to
T lymphocytes
( mature in thymus
bast cells
hepler, cytotoxic, suppressor T cells
B lymphocytes
(mature in bone marrow
enlargement of B cells
plasmablast
plama cells
produce n secrete antibodies Ab
memory cells