immune system 1 Flashcards
what is immunology
study of physiological mechanisms that humans and animals use to defend their bodies from invasion by all sorts of organisms. to provide immunity, the immuno-system has to be the forst battle of defense
what is an immunogen
a molecule that stimulates the immune system to produce a response
what is an antigen
part of the immunogen that reacts is identified as foreign and triggers an immune response
what is an epitope
part of the antigen that reacts with immune effector cells or soluble antibodies
what are the 4 main types of pathoegns
bacteria
virus
fungi
parasite
myeloid cells classification (granulocytes)
neutrophils
eosinophil
basophil
myeloid cell classification (antigen presenting cell)
monocyte
macrophage
dendric cell
whatare the 3 myeloid cell classifications
antigen-presenting cells
mast cells
granulocytes
lymphoid cell classifcations
1)small lymphocytes
b cells
t cells
2) large lymphocytes
NK cells
what are the primary lymphoid tissues
bone marrow: soft and spongy tissue that fills cavity bones
B and T cells originate in it
B cells mature whereas T cells leave immature
thymus: located above the heart
immature T cells from bone marrow migrate here, as they differentiate they progress from cortex to medulla
what are the secondary lymphoid tissues
sites where mature lymphocytes are activated to respond to invading pathogen
Lymphatic vessels originate in the connective tissues throughout the body where they collect the plasma fluid that continually leaks out from blood vessels
* Lymph nodes lie at the junctions of a network of lymphatic vessels
* This fluid, called lymph, is returned to the blood vessels via the thoracic duct
* Circulating lymphocytes can move from blood capillaries to lymph nodes where they can eventually meet a pathogen
what occurs at the lymph nodes in the secondary lymphoid tissues
- Arriving lymphocytes segregate in different areas of the lymph node
- During an infection pathogens are drained in lymph nodes from the afferent lymphatic vessels where they are trapped by dendritic cells and macrophages
- B and T cells “meet” the pathogen and are activated, undergo clonal expansion and differentiation
- As the lymphocytes grow in number, the lymph node increases in size (swollen glands)
what are the two types of immunity
adaptive immunity and innate immunity
differenced between adaptive and innate immunity
innate is rapid and takes a few hours and does not leave memory cells, whereas adaptive immunity takes a few days and creates memory cells
innate immunity is fixed whereas adaptive varies
innate immunity has limited specificity whereas adaptive immunity is highly specific
what are the immediate innate immunity responses
barriers
antimicrobial peptides
complement system
what is the complement system
group of 30 proteins that work in an orderly system
they have an inital action and a highly regulated enzymatic cascade
what are the 4 roles of the compliment system
1) Some activated proteins bind covalently to bacteria (opsonin). Bacteria are then phagocytosed by cells with complement receptors
2) Some small fragments (C3a and C5a) of complement recruit phagocytes to the site and regulate the inflammatory response
3) Some products activate B cells
4) Terminal component of system generates Membrane Attack Complex
(MAC), which causes the Lysis of pathogen
what are the two pathways in the complement system
classical pathway
alterative pathway
what are main phagocytosis cells
1) neutrophils
short-lived cells
multilobed nucleus
abundant sites of acute inflammation
2) mononuclear phagocytoses (monocytes and macrophages)
blood monocytes
longer lived
also antigen presenting cells
what is the process of phagocytosis
opsonization: makes a pathogen more susceptible to be engulfed
the pathogen is then engulfed and killed using lysosomal enzyme
cytokines production
- Low molecular weight proteins - (5-25kDa) secreted by cells that stimulate or inhibit the activity, proliferation or differentiations of other cells
- Around 20 Cytokines - include sub groups interferons, lymphokines, interleukins, chemokines
1. Mediators and regulators of innate immunity
– Produced mainly by mononuclear phagocytes (neutrophils and macrophages) in response to infectious agent
2. Mediators and regulators of adaptive immunity
– Produced mainly by T lymphocytes in response to specific recognition of foreign antigens
3. Stimulators of hematopoiesis – Produced by bone marrow stromal cells, leukocytes and other cells and stimulate the growth and differentiation of immature leukocytes
