lecture 32 Flashcards
(9 cards)
what is the inflammatory response?
Chemical signals from tissue resident cells act to attract
more cells to the site of injury
or infection -> Neutrophils enter blood from the bone marrow -> Neutrophils cling to the capillary wall -> Chemical signals from tissueresident cells dilate blood
vessels and make capillaries
‘leakier’ -> Neutrophils squeeze through the ‘leaky’ capillary wall and follow the chemical trail to the injury site
stages of phagocytosis
- Phagocyte adheres
to pathogens or debris - Phagocyte forms
pseudopods that
eventually engulf the
particles, forming a
phagosome. - Lysosome fuses
with the phagocytic
vesicle, forming a
phagolysosome. - Toxic compounds
and lysosomal
enzymes destroy
pathogens. - Sometimes
exocytosis of the
vesicle removes
indigestible and
residual material.
how does Killing and digestion of phagocytosed
microbes work
- low pH
- Reactive oxygen (hydrogen peroxide) and reactive
nitrogen intermediates (nitric oxide) - enzymes e.g protease, lipases, nucleases
what are the 3 complement cascade pathways
- classical, Antibody bound
to pathogen binds complement - alternative, Pathogen binds
complement to surface/pathogen component - lectin, Carb components of
microbes bind complement
what is a complement in the complement cascade
9 major proteins/protein complexes act in sequence to clear pathogens from
blood and tissues
what are the 3 outcomes from the complement cascade
- label/opsonisation
- destroy
- recruit
what is opsonisation and what complement is used
- coating of microbe
- either antibody or C3b
what is recruit and what complement is used
- Phagocytes attracted into site
- Mast cells degranulated by C3a and C5a
- Inflammatory mediators released including proteins
that attract phagocytes
what is destroy and what complement is used
- microbes coated with C3b are phagocytosed
- assembly of the MAC (membrane attack complex) causes lysis
