2-overview of immune system I Flashcards
4 major categories of pathogens immune response fight against
Virus-retrovirus
Parasite-filaria
Bacterium- M.tuberculosis
Fungus- C.albicans
Different pathogens require…
different immune responses
A major difference is between microorganisms we have to deal with is
Intracellular microorganisms – virus
Extracellular microorganisms – bacteria
explain Intracellular & extracellular microorganisms and what are there impact on our immune response
-processed differently
-generate different types of responses
intracellular: replicate inside cell
extracellular: replicate outside of cell
Immune response is….., involves….., sometimes can….
-Complex
-Involves molecules/cells/tissues over time
-In different locations
-Sometimes can result in life-long immunity
2 interconnected immune responses
Innate immunity – 1st line of defense (fast/non-specific)
Adaptive immunity – highly diverse/specific
organs & tissues in immune system
Bone marrow
Thymus
Lymphatics (lymphatic system)
Lymph nodes
Primary (Central) lymph organs
where immune cells are generated
example of primary lymph organs
Bone marrow
Thymus
Secondary (PERIPHERAL) lymphoid organs
where immune cells are activated
example of Secondary (PERIPHERAL) lymphoid organs
Lymph nodes - especially
Spleen
Mucosal associated lymphoid tissues (malt)
Other diffuse and loosely organized areas
how are Secondary (PERIPHERAL) lymphoid organs connected together?
via blood & lymphatic circulatory systems
Key cells of innate & adaptive immunity: different cells are ….
diffferent cells associated with different/both immunity
what is immune cells also known as?
leukocytes or white blood cells
where do immune cells originate from?
they originate in the bone marrow
All mature blood cells arise from 1 single cell type
HSC, hematopoietic stem cell
what is hematopoiesis
process HSCs differentiate into mature blood cells in bone marrow
what are the 2 lineages in the origin of immune cells?
Common lymphoid progenitor
Common myeloid progenitor
what cells does lymphoid lineage generate
Mainly adaptive immune cells:
B&T lymphocytes (cells)
ILC-innate lymphoid cells
(NK cells)
what cells does myeloid lineage generate
Most other leukocytes:
Granulocytes:
Neutrophils
Eosinophils
Basophils/Mast cells (inflammation/allergies)
Monocyte which eventually becomes macrophages
One cell that can arrise from both progenitor
Dendritic cells - bridge innate and adaptive immune system
what happens when the cells are developped?
reside in tissues/organs OR circulate in blood/in lymphatic system
red blood cells from myeloid lineage
erythrocytes: carry O2 to cells/tissues & can generate antimicrobial compounds
what does Megakaryocytes do…
give rise to platelets (blood clotting)
what happens to monocyte from myeloid lineage, what is its role?
migrate into tissues & differentiate into macrophages
Repair/remodel, destroy pathogens, present antigens (triggers our immune response)
what are Macrophages/immature dendritic cells/neutrophils from myeloid lineage specialized for?
Phagocytosis, cellular uptake by engulfment
what can macrophages do?
phagocytosis & present anitgens to T cells
What happens to immature DC after it phagocytoses an antigen?
mature & migrate out of the location to another – to present antigen to T cells
what are Dendritic cells?
Key bridge in immune response:
-this is how they bridge between innate & adaptive
Activate adaptive immunity
-most potent antigen-presenting cells – for activating naive T cells
Involved in detecting infection
Lymphocytes (B&T cells): similarity & differences
Appear very similar
Different sets carry different clusters of differentiation (CD) molecules on their surface
what are B&T cells responsible for?
adaptative immunity (Generate highly specific responses )
how is B&T cells specificity determined?
Specificity – determined by expression of receptors on cell surface
B cells – B cells receptor (BCR)
-Can be bound to membrane or secreted as antibodies
T cells – T cell receptor (TCR)
-Membrane bound
how do immune cells communicate with each other?
signaling molecules are produced by activated innate immunity
-stimulate & direct adaptive immune response
-function to communicate (between cells/inside cells) OR mediate interactions between cells
what does molecules do to cells they need to target? (5)
it can trigger changes in target cells:
activation/signaling/migration/transcription/cellular differentiation
key types of molecules: (40
Secreted proteins
Receptors on cell surface
Intracellular signaling molecules & transcription factors
Antigens
Secreted proteins communicate through (2), what are they & what do they do?
Communication through cytokines & chemokines
Cytokines: messenger proteins secreted by certain cells
Chemokines: type of cytokines that recruits specific to a site
Receptors on cell surface, what ar their roles
Cytokines & chemokines bind to target cells via specific receptors
Cells can interact via receptors
Intracellular signaling molecules & transcription factors
Many stimuli result in intracellular (inside the cell) signaling – involves signaling proteins & transcription factors
Antigens (Ag)
-Key molecule targeted by immune response
-Antigen (Ag) = any specific molecule that can trigger an immune response
-Can be a protein (most) or nucleic acid/polysaccharide/lipid/organic chemicals/drugs
what is an epitope?
Specific portion of Ag recognized by a receptor on immune cell
How does Molecules mediate actions/changes
cells interact with each other via receptors – resulting in change (Cell migration)
cells migrate to a higher concentration of chemokines
