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Immunology
Medical Microbiology and Immunology 341
57
Medical
Undergraduate 3
12/28/2008

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Cards

Term
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Definition

neutrophil

  • 60-65% of WBC
  • granulocyte; leukocyte - 3-lobed nucleus with pink granular cytoplasm
  • phagocytic: during infection, migrates from the blood to tissues where phagocytoses pathogen then dies and forms pus
  • does not present antigens
  • part of innate immune response
Term
[image]
Definition

eosinophil

  • very few in WBC - function mainly in tissues
  • granulocyte (bright orange granules); leukocyte
  • defends against internal parasites
Term
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Definition

basophil

  • few in WBC
  • granulocyte (deep purple); leukocyte
Term
[image]
Definition

monocyte

  • 5-10% of WBC
  • mononuclear; leukocyte
  • mobile progenitors of macrophages; travel in blood to tissues where mature into macrophages
Term
[image]
Definition

lymphocyte

  • 25-30% of WBC
  • monocyte; leukocyte
Term
leukocyte
Definition

white blood cells (WBC);

  • includes neutrophils, eosinophils, basophils, monocytes, lymphocytes
  • derived from hematopoietic stem cells
Term
pathogen
Definition

any organism with the potential to cause disease

  • bacteria
  • viruses
  • fungi
  • internal parasites
Term
physical barriers against infection
Definition
  • skin (epithelial): made of tough, keratinized cells; breached by physical damage
  • mucosal surfaces: covered in mucus which contains glycoproteins, and enzymes to protect from damage and infection; i.e. lysozyme in saliva
  • acidic environment in skin, stomach, and vagina
Term
innate immune response
Definition

causes inflammation at site of infection 

  1. pathogen recognition: includes soluble proteins, and cell-surface receptors
  2. recruitment of effector mechanisms: kill and eliminate pathogens; effector cells and complement
Term
cytokines
Definition

soluble proteins that act as triggers for cells

  • induce local dialation of blood capillaries (vasodilation)
  • change adhesive properties of vascular endothelium: easier for WBC to enter tissue from bloodstream (infiltration)
Term
adaptive immune response
Definition

highly specialized defense against a specific pathogen

  • cell-surface receptors are highly specialized
  • long-term immunological memory: faster, stronger response on next exposure (acquired or protective immunity)
Term
acquired or protective immunity
Definition

memory cells within the body that allow a stronger, faster adaptive immune response to a pathogen; usually due to prior exposure to the same pathogen;

immunological memory

Term
primary response
Definition
the first time an adaptive immune response is made to a specific pathogen
Term
secondary response
Definition
the second (or more) time an adaptive immune response is made to a specific pathogen - immunological memory (acquire immunity) applies
Term
erythrocytes
Definition
reb blood cells
Term
[image]
Definition

 macrophage

  • phagocytic cell: dispose of dead cells as well as foreign invaders
  • professional antigen presenting cells
  • 5% of blood cells
  • resident in tissues
  • express MHC class II
  • part of both innate and adaptive immune responses
  • secrete cytokines
Term
[image]
Definition

 dendritic cell

  • monocyte; leukocyte; phagocytic
  • distinctive star shape
  • act as cellular messengers for adaptive immune response
  • reside in tissues but bring/present antigens to T cells
Term
[image]
Definition

 mast cell

  • monocyte; granulocyte (contain histamine); leukocyte
  • reside in tissue
  • major contributor to inflammation and allergies
  • histamine released within 5-10 min of contact with antigen
  • contributes to anaphalaxis
Term
[image]
Definition

natural killer (NK) cell

  • large granular lymphocytes
  • part of innate immunity
  • kill virus-infected cells; secrete cytokines
  • no specific antigen receptor
Term
B lymphocytes or B cells
Definition
  • antigen receptors are immunoglobulins
Term
phagocytosis
Definition
  • engulfment and destruction of particulate material; i.e. bacteria
  • neutrophils, macrophages, dendritic cells
  • mechanisms of killing: acid; anti-microbial peptides ("defensins"), superoxides/hydrogen peroxide, nitric oxide, proteolytic enzymes
  1. antigen binds to cell receptors (can be antibody mediated/Fc receptors)
  2. engulfment: membrane surrounds and fuses around antigen forming a membrane-bound vesicle (phagosome)
  3. degradation: vesicle fuses with lysosome, containing destructive materials (see 'mechanisms of killing' above) to form phagolysosome - some intracellular bacteria prevent this phase and infect the cell instead
Term
T lymphocytes or T cells
Definition
  • antigen receptors are T-cell receptors (TCRs)
Term
primary or central lymphoid tissue
Definition

where lymphocytes develop and mature;

include the bone marrow and thymus

  • bone marrow: where B-cells develop and mature; where T-cells develop
  • thymus: where T-cells mature
Term
lymphocyte
Definition

white blood cells

  • large: natural killer cells (innate); granular cytoplasm
  • small: B cells, T cells (adaptive); little to no cytoplasm - mature lymphocytes travel through the blood, secondary lymphoid tissues, and lymphatics, then back to the blood (recirculation) but the majority are in the the lymphoid organs and tissues
Term
secondary or peripheral lymphoid tissue
Definition
  • all other lymphoid tissue except bone marrow and thymus - includes spleen, adenoids, tonsils, appendix, lymph nodes, and Peyer's patches (in the gut)
  • where mature lymphocytes are activated
  • connected (except for the spleen) to the lymphatic vessels which drain the extracellular fluid and return it to the blood (lymphatics)
  • provide signals that keep circulating lymphocytes alive

 

Term
lymph node
Definition
  • lymph arrives from afferent lymphatic vessels and leaves via the efferent lymphatic vessel
  • lymph is filtered by macrophages as it travels through the node
  • dendritic cells take up residence in the T-cell areas
  • circulating small lymphocytes from the blood and lymph enter the node - become activated through interactions with dendritic cells and each other
Term
plasma cells
Definition
  • effector B cells
  • make and secrete antibody
  • either stay in lymph node or migrate to bone marrow
Term
CD8 cytotoxic T cell
Definition
  • effector T cell that kills infected cells
Term
TH1 helper T cells
Definition
  • effector T cells
Term
TH2 helper T cells
Definition
  • effector T-cells
Term
hematopoiesis
Definition

formation of blood cells

  • all blood cells from hematopoietic stemm cell (HSC) in bone marrow
  • programmed set of steps
  • when HSC proliferates it forms a "progenitor cell" and a new HSC
Term
autologous bone marrow transplant
Definition

adult stem cell transplantation

  • Restores ability to make WBC in individuals w/o HSC
  1. remove bone marrow and freeze
  2. hi dose chemotherapy to destroy HSC
  3. return HSC removed earlier
Term
antibody
Definition
  • soluble form of immunoglobulin
  • the constant region has binding sites for cell-surface receptors (Fc receptors) on phagocytes, complement, and other cells
Term
spleen
Definition
  • red pulp filters the blood: (innate response)
    • removes damaged/old red blood cells
    • macrophages filter out infectious agents like blood borne bacteria (even non-opsonized ones)
  • white pulp: site of lymphocyte activation to antigens in the blood (adaptive response)
  • part of the secondary lymphoid tissue
  • connected only via blood
Term
Total WBC count
Definition
  • uses whole blood sample
  • counts # of cells in known volume and calculates concentration in WBC/microliter
  • normal = 5,000-10,000 WBC/microliter
Term
differential WBC count
Definition
  • uses blood smear prepared with Wright's Stain and 100x microscope with oil immersion
  • count 100 WBC
  • find percentage of each WBC type: normally
    • neutrophils: 60-65%
    • monocytes: 5-10%
    • lymphocytes: 25-30%
    • eosinophils: few
    • basophils: few
Term
absolute WBC count
Definition
  • total WBC x %
  • calculates the amount of each WBC type (WBC/microliter)
Term
leukocytosis
Definition
increased WBC count; >10,000 WBC/microliter
Term
leukopenia
Definition
decreased WBC count; <5,000 WBC/microliter
Term
leukemia
Definition

cancer of the WBC;

results in elevated WBC count = 100,000/microliter

Term
neutrophilia
Definition

increase in neutrophils;

usually also increased WBC count

 

with bands:

there are immature neutrophils which means an ongoing disease process

Term
splenectomy
Definition

removal of the spleen:

  • done for trauma or hematologic diseases
  • more susceptible to serious infections with bacteria that replicate in the blood stream
Term
neutropenia
Definition
decrease in neutrophils; usually with a decrease in WBC count
Term
mucosa-associated lymphoid tissue (MALT)
Definition
handles pathogens in the mucosal areas like the gut (GALT) and airways and other mucus membranes
Term
antigen
Definition
part/parts of a pathogen that interacts with the immune system
Term
lymph node cortex
Definition
  • mostly the B-cell area
  • where germinal centers are located
  • helper T-cells move here to stimulate the differentiation of B-cells into plasma cells (migrate to the medulla)
Term
lymph node paracortex
Definition
  • the T-cell area
  • macrophages filter the lymph
  • dendritic cells move in to interact with circulating T-cells
Term
lymph node medulla
Definition
  • the central part of the lymph node
  • plasma cells migrate here and secrete antibody
  • drains to efferent lymphatic vessel and blood
Term
epitopes or antigenic determinant
Definition
the part of the antigen that is bound by the receptor; an antigen can have several epitopes
Term
immunoglobulin (Ig)
Definition
  • formed from two polypeptides: heavy and light chains (2 identical copies of each)
  • have a variable region and constant region (both heavy and light chains)
    • variable region: binds antigen
    • constant region: indentical from one Ig to another - in membrane-bound Ig the heavy chain constant region connects to the transmembrane region that anchors the Ig
Term
heavy chain
Definition
Term
light chain
Definition
Term
T-cell receptor (TCR)
Definition
  • consists of αlpha and beta chains anchored to the membrane
  • each chain has a variable and constant region
Term
germline configuration
Definition
immunoglobulin and T-cell receptor genes in their original conformation before any rearrangement
Term
somatic recombination
Definition
gene rearrangement in the B and T cells
Term
somatic hypermutation
Definition
  • occurs in activated dividing B cells;
  • introduces nucleotide substitutions into the immunoglobulin heavy- and light- chain genes;
  • introduces varying antigen affinities and results in strengthening of antibody affinity during adaptive response
Term
Toll-like receptors (TLRs)
Definition

some of the pattern recognition receptors (PRRs) which allow the cells of the innate immune system to detect and respond to pathogens

  • 10 different kinds: capable of recognizing microbial nucleic acids and invariant molecules chracteristic of different pathogens (i.e. bacteria, fungi, viruses, and parasites)
  • signaling receptors that enhance antimicrobial activity and secretion of cytokines; induce the maturation and migration of dentritic cells
  • share a signalling pathway with IL-1 receptor
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