week 4: immune responses: part 1 & 2 Flashcards
what is a pathogen
agents that cause a disease. infects a wide range of animals, including humans
what are the immune defences
innate immunity and acquired immunity
describe innate immunity
-already exists in the body and is fast acting.
-non specific
defences include: the skin, protective secretions, cell responses.
what are barrier defences?
includes skin and mucus membranes of respiratory, urinary and reproductive tracts.
what is a macrophage
circulate in the blood and found in many different tissues. phagocytic cell derived from monocytes.
what are Neutrophils
phagocytic cells constituting over half of leukocytes.
What are Natural Killer NK cells
non-phagocytic type of lymphocyte.
what does a macrophage do
engulf and kill invading microorganisms. induces inflammation.
what do neutrophils do
cytoplasm is packed with granules. takes up variety of microorganisms and kills them using granule contents
what do Natural Killer (NK) cells do
has a granular cytoplasm recognize and kill abnormal cells. holds viral infection in check before adaptive immune system kicks in.
what do NK cells target
body cells which have been infected by a virus.
what does the NK cell do after encountering an infected cell
releases proteins called perforins and creates pores in the plasma membrane of the target cell.
what do granzymes do and where are they from
from NK cells
break down proteins and in doing so destroy the infected cell and the virus.
what are mast cells
connective tissue that releases histamine which triggers blood vessels to dilate and become more permeable.
what releases cytokines to enhance immune response
activated macrophages and neutrophils.
what orchestrates the allergic response
over stimulation of mast cells.
what two cells are part of the acquired immune system
B and T lymphocytes
how do B and T lymphocytes bind to antigens?
antigen receptors
The small accessible part of an antigen that binds to an antigen receptor is called an _________.
epitope
what does the T lymphocyte do
causes death of the infected cell
what does the B lymphocyte do
produces antibodies
how are antigens exposed to T cells?
through a process called antigen presentation. this involves a protein complex called the major histocompatibility complex. which is expressed on the surface of all cells
what is the MHC
the major histocompatibility complex which is expressed on the surface of all cells.
what is the difference between MHC class 1 and class 2
all nucleated cells express MHC class.
expression of MHC class 2 is restricted to macrophages and B cells.
