immune system Flashcards
the immune system is a set of — — that works with the — system to — — — — (aka pathogens) that enter the body
specialized cells; lymphatic; fight off foreign substances
there are two types of defenses
-innate (non-specific) defenses
-acquired (adaptive) defenses
innate (non-specific) defense
-work quickly but arent specialized for individual pathogens
–skin and mucous membrane
acquired (adaptive) defense
-works slowly but provides specialized and long-lasting defense
–humoral immunity and cell-mediated immunity
innate resistance starts with barriers
-external barriers: prevent pathogens from entering the body
-internal barriers: activated once pathogen passes into body tissues
external barriers
-SKIN: keratinized cells create a physical barrier
–produces oil and sweat which inhibit growth of bacteria
-MUCOUS MEMBRANE: mechanical elimination
–mucous physically traps pathogens and cilia of the respiratory track can sweep them towards the mouth for removal.
-SECRETIONS: gastric juice from stomach, saliva, and tears all contain enzymes that kill pathogens
internal barriers
-PHAGOCYTES: “eat” foreign invaders
–neutrophils: kill bacteria, then die (creating pus)
–macrophages: move with cytoplasmic extensions to ingest pathogens
-NATURAL KILLER CELLS: lyse (explode) infected/abnormal body cells based on a lack of “self” surface receptors
-IMFLAMMATION:
–basophils and mast cells stim, blood vessels to dilate/widen
–swelling (edema) allows macrophages to quickly arrive through vessels
–pyrogenic chems cause fevers, which increases cell metabolism to speed up repair
-ANTIMICROBIAL PROTEINS:
–complement proteins: work with other defenses by lysing pathogenic bacteria or making pathogens for easier phagocytosis (opsonization)
–interferons: warning signal proteins secreted by virally-infected body cells. these are a type of cytokine
—cytokine: chem signals used to help cell communicate during immune response
if the non-specific defenses dont stop the infection, the body will create an immune response — to that —
specific, pathogen
substances that trigger responses are called —
antigens
the cells responsible for the specific response are called —
lymphocytes
lymphocytes produce — that match certain —
antibodies; antigens
the acquired immunity portion of the immune response must be able to
- discriminate between self and non-self antigens
- recognize a specific antigen among trillions of possible substances
- generate a large diversity of antibodies so any possible substance can be recognized and eliminated
- provide memory of antigens
discriminate between self and non-self antigens
lymphocytes that act against self-antigens are destroyed
recognize a specific antigen among trillions of possible substances
each lymphocyte only has surface receptors for one antigen
provide memory of antigens
a 2nd exposure to an antigen is immediately recognized and infection is barely noticed
two types of acquired (specific) immunity
-humoral response
-cell-mediated response
humoral response
-involves B cells
-responds to antigens before they infect body cells
cell-mediated response
-involves t-cells
-responds to body cells that have already been infected with foreign pathogens
immunity can be — or —
earned; borrowed
steps of the humoral response
- B-lymphocytes (B-cells) recognize a foreign antigen
- B cells rapidly divide creating cloned plasma b cells and memory b cells
- memory b cells are long-lived and produce a swift and strong response if the same antigen is encountered in the future (“secondary response”)
- the antibodies produced by the plasma B cells can:
-neutralize the antigen by physically surrounding it
-immobilize the antigen by agglutination (clumping, which flags macrophages to go eat it)
-activate macrophages to destroy antigen
active immunity is — because it is developed by the creation of our own antibodies
earned
passive immunity is when we — the immunity that another individual has already created
borrow
for cell-mediated immunity, in order to amplify the immune response, — can also act as — — —
B-cells; antigen-presenting cells
antigen-presenting cells — — and present pieces of the antigen to other immune cells. this is the sounding alarm for an infection to recruit more warriors for the fight
engulf antigens
antigen-presenting cells include
B-cells, macrophages, and dendritic cells
the antigen fragment is presented on a — known as an MHC-II. T-cells will bind to this and mount a — response against the antigen
receptor; stronger
steps in the cell-mediated response
- after the antigen-presenting cells display the foreign antigen to a helper T-cell, the T-cell is activated
- a signaling cascade begins, creating more helper and memory T-cells
- some of the cytokine signals activate cytotoxic T-cells, which bind to infected body cells and cause apoptosis
- regulating T-cells release chemicals to slow the immune response after the antigen is destroyed
which cells are used to react quickly to a secondary infection (re-infection with a previous pathogen)
memory b and memory t-cells
how can the secondary response be artificially produced?
vaccines can help the body mimic the first infection
