Unit III "Disease & Immunity" Flashcards
structure of a virus
nucleic acid wrapped in a protein coat
lytic cycle
once phages enter the cell, the bacterium breaks open
lysogenic cycle
viral DNA replication occurs without phage production or death of the cell
cocci
spherical prokaryotic cells
bacili
rod shaped cells
binary fission
cells copy their DNA almost continuously and divide again and again
endospore
protective cell produced within the prokaryotic cell when cell is exposed to unfavorable conditions
what are the three domains of life?
bacteria, archaea, eukarya
pathogens
disease causing organisms and bacteria
exotoxin
proteins that bacterial cells secrete into their environment
endotoxins
chemical components of the outer membrane of certain bacteria
symbiosis
close association between organisms of two or more species
endosymbiosis
one species living inside another host species
immune system
body’s system of defenses against infectious disease
phagocytic cells
engulf foreign cells or molecules and debris from dead cells
natural killer cells
recognize virus-infected or cancerous body cells. when in contact, NK release chemicals that kill the diseased cells
interferons
bind to plasma membrane receptors of uninfected proteins, stimulates them to build proteins that inhibit viral reproduction
complement proteins
attack pathogens directly, coat surfaces of microbes, making the, easier for phagocytic to engulf
histamine
causes blood vessels to dilate and leak fluid into the wounded tissue (causes swelling)
lymphocytes
white blood cells that recognize and respond to specific invading pathogens
B cells
lymphocytes that continue maturing in the bone marrow
T cells
lymphocytes that migrate to the thymus
antigen
molecule that elicited a response from a lymphocyte
what are the functions of B cells and T cells?
recognize a single specific type of antigen and mount an immune response against it
antibody
marks an antigen by combining with it to dorm an antigen-antibody complex
effector cells
secrete huge amounts of antibodies into the blood and lymph
primary immune response
antibodies produced by effector B cells reach their peak levels about two weeks after first exposure
memory cells
long-lived cells that respond to subsequent exposures to the antigen by giving rise to effector cells and more memory cells
secondary immune response
memory cells that find to the antigen intimate a faster and stronger response
vaccine
harmless version of a disease-causing microbe; stimulates immune system to mount defenses against antigens
humoral immune response
secretion of antibodies into the blood and lymph by B cells
cell mediated immune response
effector T cells respond directly to antigens and have already entered body cells
helper T cells
bind to other white blood cells that have previously encountered a pathogen
what is the function of helper T cells?
stimulate the activity of cytotoxic T cells and help activate B cells
cytotoxic T cells
only T cells that kill infected cells; death by lysis
allergies
exaggerated sensitivities to otherwise harmless antigens in the environment
lymph nodes
round organs packed with white blood cells
