intro to immunology Flashcards
functions of immunity
immune defense: how human/animal respond to pathogens
immune homeostasis: how immune system balances
immune surveillance: monitoring immune system => activated if something happens
innate immunity aka active
immunity from birth
- very broad defense
- patter recognition, but no specificity
- no memory
- temperature: increase temperature, pathogens can’t survive
- pH: pathogen has pH 7 but our stomach is acidic
- barriers (skin, feathers)
- microflora: on any surface on skin, mouth, nose etc.
- cilia: microorganisms provide physical layer of protection and environment is hostile to pathogen
- cells (neutrophils, macrophages)
- complement
- serum proteins (in blood that immediately take action)
adaptive immunity aka acquired immunity, also passive immunity
acquired, takes time
- developing certain response to pathogens
- mediated by lymphocytes
- memory
- specificity
- specialization
ex: immunity from vaccine
- B cells (from bursa of Fabricius or bone marrow) => generate antibody IgM, IgG, IgE, IgA
- T cells (from thymus)
- killer and helper T cells
what is the most abundant cell type in the blood
neutrophil
mechanisms of immunity
barriers (innate)
- physical: skin and mucosa
- chemical: antimicrobial substances in secretion of skin and mucosa
- biotic barrier: normal flora existing on the surface of skin and mucosa
- anatomic: blood brain barrier, blood placental barrier (protect fetus), blood thymus barrier (where T cells are)
humoral factors (innate)
- complement
- lysozyme
- interferons
- C-reactive protein
cells participating in innate immunity
phagocyte: endocytosis and phagocytosis mononuclear phagocytes
- monocytes
- neutrophils, eosinophils: phagocytes that identify and kill pathogens
- natural killer cells (NK)
- dendritic cells
- basophils
- mast cells
myeloid cells of immune system
neutrophil
function: phagocytosis and activation of bactericidal mechanisms
- polymorphonuclear
- phagocytosis: specialize in the capture, engulfment, and killing
- short life span (hours)
- work in anaerobic conditions (damaged tissues)
- massive migration to site of infection => first responder once they receive signal
monocytes (blood)/macrophage (tissue)
- phagocytosis and the killing of microorganisms => activation of T cells and initiation of immune response
- there are tissue-specific macrophages => “resident macrophage”
- antigen-presenting cells
macrophage
function: phagocytosis and activation of bactericidal mechanisms, antigen presentation
- Elie Metchnikoff coined the term macrophages and first described phagocytosis in starfish embryos
- long lived
-first cell to sense invading microorganism - secrete the cytokines that recruit neutrophils and other leukocytes
dendritic cell
function: antigen uptake in peripheral sites, antigen presentation
- in the blood and tissues - mature and migrate to lymph nodes
-distinctive star shaped- act as cellular messengers that call up an adaptive immune response
- antigen presentation in lymphoid organs
immature dendritic cells reside in peripheral tissues -> migrate via lymphatic vessels to regional lymph nodes -> mature dendritic cells activate naive T cells in lymphoid organs such as lymph nodes
an innate lymphocyte
- B lymphocyte is antigen-presenting cell
- NK cells do not require prior immunization or activation
- attach to target cells
- cytotoxic granules are released onto surface of cell
- effector proteins penetrate cell membrane and induce programmed cell death
- 2 functions: kill virus infected cells, impede viral replication by secreting cytokines
once virus gets into cell => has to kill whole cell
pathogen associated molecular patterns (PAMP)
allows the immune cell to recognize the pathogen as infectious agent
