immune system quick flashcards

what is innate immunity

nonspecific

immediate defense against infection

doesn’t give long lasting protection

include humoral and cell mediated immunity components

what is adaptive immunity

specific

long term immunity

slow response

what are some physical barriers in the immune system

lysozyme in tears kill bacteria

skin as a physical barrier

mucus and cilia capture organisms and remove them

what is inflammation

upon activation, PRRs and PAMPs release inflammatory mediators (histamine, leukotrients, etc) which attracts phagocytes

vasodilation and increased vascular permiability allows fluid, protein, inflammatory cells to enter tissue

infected tissue becomes inflamed, causing redness, heat, swelling, pain

what are toll like receptors

germline encoded PRRs

mainly found on macrophages, mast cells and dendritic cells

what are nod like receptors

sense infection and stress through recognition of cytoplasmic PAMPs

what are RIG-I-Like receptors and Cytosolic DNA sensorys

intracellular sensors that detect viral of bacterial infections in the cytoplasm

what are C-Type Lecitn receptors

trigger anti fungal responses

what are macrophages

most efficient phagocytes

use respiratory burst to kill pathogens

what are neutrophils

they are circulating phagocytes

use granules and respiratory burst to kill pathogens

what are dendritic cells

phagocytic cells in tissues that are in contact with the external environment

what are mast cells

in connective tissue and mucous membranes

eg histamine, heparin, chemokines

what are basophils and eosinophils

basophils: histamine, parasites, allergic reaction

eosinophils: worm, viral, allergy

what are natural killer cells

destroy compromised host cells lacking MHC expression

eg virus infection, cancer

what are gamma delta T cells

less common in humans

gastrointestinal site

what is the complement sysytem

helps antibodies and phagocytic cells clear pathogens from an organism

around 30 proteins found in the blood circulate as inactive precursors

what is the classical pathway

antibody binds to specific antigen on pathogen surface

activates complement

C3b binds covalently to surface of pathogen

what is the lectin pathway

mannose binding lectin binds to pathogen surface

activates complement

C3b binds covalently to surface of pathogen

what is the alternative pathway

pathogen activates the complement itself

activates complement

C3b binds covalently to surface of pathogen

what does the covalent binding of C3b to pathogens result in

recruitment of inflammatory cells or

opsonization of pathogens or

perforation of pathogen cell membrane

leading to death of pathogen

what is a humoral response

antibodies defend against infection in body fluids

what is a cell mediated response

cytotoxic cells defend against infection in body cells

what are antigens

substances that can elicit a response from a B or T cell

what is an epitope

the small part of an antigen that binds to an antigen receptor

explain the process of antigen presentation

antigen enters dendritic cell

enzyme breaks antigen into pieces

pieces bind to MHC protein inside ER

MHC antigen transported to cell surface via golgi apparatus

MHC protein presents antigen on surface of cell membrane

what are class I antigens

intracellular antigens

MHC Class I

what are class II antigens

extracellular antigens

MHC Class II

what cells present antigens

Class I and II antigens

dendritic cells

lymph nodes

what are haematopoietic cellss

produced in bone marrow

T cells mature in thymus

B cells mature in spleen and secondary lymphoid organs

what does antibody production trigger

pathogen and toxin neutralisation

classical complement activation

opsonophagocytosis

what’s different between secreted antibodies and B cell receptors

secreted antibodies lack transmembrane regions that anchor receptors in the plasma membrane

what is neutralisation

antibodies bind to viral surface proteins, prevent infection of a host cell

antibodies may bind to toxins in body fluids and prevent them enetering cells

what are the immunoglobulin classes

IgD - membrane bound

IgM - first soluble class produced

IgG - second soluble class, most abundant

IgA and IgE - remaining soluble classes

what are cytotoxic T-cells (CD8)

use perforin and granzymes that trigger apoptosis

what are helper T cells (CD4)

Th1 - intracellular

Th2 - extracellular

activate other immune cells to fight infection

what is active immunity

memory cells form clones in response to infection

can also develop following vaccination

what is passive immunity

provides immediate, short term protection

naturally: mother feeding baby breast milk

artifically: injecting antibodies into a nonimmune person

what are memory T cells

antigen specific T cells

quickly converted into effector T cells upon reexposure of the specific antigen

what are memory B cells

upon re exposure to the same antigen, they rapidly proliferate and differentiate into plasma cells

produces larger and more effective antibody response