7C - Second Line of Defence Flashcards
second line of defence
component of the innate immune system characterised by the nonspecific and immediate response to injury and pathogens by a
variety of cells and molecules
phagocytosis
a process in which phagocytes consume and
destroy foreign or dead material present in the body by engulfing it through the process of
endocytosis.
leukocytes
a group of blood cells
responsible for protecting the body against pathogens and foreign
material. Also known as white blood cells
phagocyte
a group of leukocytes
responsible for the endocytosis and destruction of pathogens,
foreign material, and cell debris
what occurs after phagocytosis engulfs
Once engulfed, lysosomes containing antimicrobial enzymes called lysozymes
present in the cell destroy the foreign or dead material by fusing with the vesicles containing the engulfed material.
3 types of phagocytes
neutrophils, macrophages, and dendritic cells.
neutrophil
most common leukocyte Engages in phagocytosis of pathogens and
foreign material, as well as the release of cytokines
cytokines
small proteins that act as chemical messengers in the immune system, controlling the growth and activity of other cells
macrophage
a type of leukocyte
found throughout the body that engages in phagocytosis and
antigen presentation
dendritic cell
a type of leukocyte
that engages in phagocytosis and
antigen presentation
antigen-presenting cell
phagocytes that display antigens from consumed
pathogens on their surface and interact with the adaptive immune
system. Also known as professional
antigen-presenting cell
examples of antigen presenting cells
macrophages and dendritic cells
natural killer (NK) cell
type of leukocyte responsible for the
recognition and destruction of
damaged and/or infected host cells
two receptors on NK cells
a killer inhibitory
receptor and a killer activation receptor
killer inhibitory receptor –
* killer activation receptor
examines the surface of cells for MHC Class I markers
- binds to certain molecules which appear on cells undergoing
cellular stress (e.g. infected or cancerous cells).
inflammatory response
series of biochemical events that occur
in the body as a result of infection and/or trauma. Characterised by
swelling, redness, pain, and heat in
the affected tissue
eosinophil
a large granular
leukocyte responsible for the release of toxic chemical mediators
interferon
a cytokine released by
virally infected cells that increases the viral resistance of neighbouring
uninfected cells
mast cell
a type of leukocyte
responsible for releasing histamine during allergic and inflammatory
responses
cellular components of second line of defence
phagocytes
Natural Killer Cells
Mast Cells
Eosinophils
non cellular components of second line of defence
interferons, complement
proteins, and the initiation of a fever.
complement proteins
a number
of different types of proteins found
in the blood that opsonise, cause lysis, and attract phagocytes to
invading pathogens
The three major
outcomes of complement cascade
Opsonisation
chemotaxis
lysis
Opsonisation
Complement proteins stick on the outside
surface of pathogens and make it easier
for cells of the immune system, such as
phagocytes, to recognise them as foreign.
chemotaxis
Complement proteins gather near a
pathogen and attract phagocytes to it,
making it more likely to be destroyed.
lysis
Complement proteins can join together
on the surface of pathogens
- forming a
membrane attack complex (MAC) - creates pores in their membrane.
destroys the pathogen by causing lysis via
the sudden influx of fluid into the pathogen,
causing it to burst.
process of inflammation
– initiation, vasodilation,
and migration.
