U4 AOS1 Chp 5 Definitions Flashcards
VCE Unit 4 AOS 1 Biology Chp 5 content from Jacaranda Biology Textbook
Antigens
Unique molecules or parts of molecules that can often elicit an immune response, through the adaptive immune response and so play a crucial role in immunity
Allergens
Any antigen that causes the immune system to produce an abnormal and inappropriate overaction when a person is exposed to it
Allergic reactions
specific type of immune response in which the immune system overreacts to a normally harmless substance.
Clonal deletion
2 stage process of selecting T lymphocytes that recognise MHC proteins and eliminating those that react to self antigens
Self tolerance
Inability to respond to self antigens (if this breaks down = autoimmune disease)
MHC – 1 Markers
Nucleated cells have these to recognise as self.
MHC – 11 Markers
Markers on leukocytes (white blood cells) and antigen-presenting cells that present antigens to the immune system
Pathogen
Agents that cause disease
Primary pathogen
cause disease any time they are present
Opportunistic pathogen
only cause disease when the hosts defences have been weakened
Exotoxins
secreted toxins
Endotoxins
parts of the outer membrane that are released when bacteria die
Antigenic variation
mechanism by which surface antigens change
Anthropods
invertebrates with external skeletons that are able to transmit or cause disease to humans
Viron
composed of genetic material enclosed in a protein
Antigenic drift
some viruses constantly make minor changes to the antigens on the surface
Viroid
type of self cleaving RNA enzyme composed of short circular RNA strands that lack protein coat
Prions:
infectious agents composed primarily of proteins that are abnormal normal cell protein produced by gene mutations
Innate immunity
nonspecific defence mechanisms that come into play immediately of an antigen’s appearance in the body
Adaptive immunity
refers to antigen-specific immune response that operates only after innate immune defences are overwhelmed.
surfactants
coat the pathogens making it easier for them to be eliminated by macrophages
normal flora
nonpathogenic bacteria found on the skin and in the mouth, nose, throat, lower part gastrointestinal tract and urogenital tract in healthy individuals
Toll-like receptors (TLR)
pattern recognition molecules on leukocytes that are able to recognise microbial molecules PAMPS
Pathogen-associated molecular patterns (PAMPs)
Microbial molecules that are common to a range of pathogens
Phagocytes
Leukocytes that engulf and break down pathogens via phagocytosis including macrophages, neutrophils and dendritic cells
Neutrophils
Usually the first cells to arrive at the site of an infection that contain toxic substances to kill or inhibit growth of bacterial or fungal pathogens and release cytokines that amplify the immune response and recruit other cells
Macrophages
eliminate and engulf pathogens by phagocytosis , recruit other immune cells to infection site and act as antigen presenting cells
Dendritic cells
eliminate and engulf pathogens by phagocytosis, act as messengers between the innate and adaptive system as an antigen presenting cell
Eosinophils
granulocytes that are present in the respiratory, gastrointestinal and urinary tracts that assist in defending against larger parasitic agents too large to be engulfed by phagocytosis
Natural killer cells
lymphocytes that kill virus-infected cells by apoptois
Mast cells
release histamines that increase vascular permeability and release cytokines that attract other immune cells to help destroy the pathogen
humoral innate immunity
involves actions of soluble active molecules such as complement proteins and cytokines
Complement proteins
an array of more than 30 proteins that circulate the blood and help kill foreign cells by an enzyme triggered reaction leading to lysis of invading pathogens.
opsonisation
some complement proteins cover the surface of a pathogen to format complex with the surface antigens on the pathogen, making them more susceptible to elimination by phagocytosis as the complement protein binds with the complement protein on phagocytes.
chemotaxis
refers to the movement of cells in response to a chemical stimulus
cytokines
small signalling molecules that coordinate many aspects of our immune response
Interferons
class of cytokines that are produced by and act on a host cell infected with a virus
chemokines
type of cytokine that acts as a chemical attractant
Inflammation
beneficial, defensive response triggered by damage to the body’s tissues by physical agents, microbial infection or chemical agents
Lymphatic system
network of vessels that drain lymph fluid from the tissues back into the circulatory system
extravasation
cells and fluid are able to pass between closed blood and lymph capillaries
lymph
fluid in the lymphatic system that is squeezed out of blood vessels
Tissue fluid/interstitial fluid
fluid leaks from capillaries
lymph nodes
oval or bean-shaped structures throughout the body that filter lymph and store lymphocytes
spleen
controls the number of red blood cells in the body by destroying old and defective red blood cells
Helper T cells
do not directly kill pathogens, they express cd4 receptors that activate cytotoxic T cells, B cells and other immune cells
Humoral adaptive immunity
involves actions of antibodies that identify and bind to extracellular pathogens, to toxins and to other extracellular foreign antigens
Cell mediated adaptive immunity
involves various actions of T cells to eliminate intracellular pathogens
plasma cells
‘factories’ specialising in antibody production
Variable regions
amino acid sequence that forms top of the arms allowing antibodies to bind to different antigens
Constant region
stem of Y shape is a conserved sequence in all antibodies that recruits other components o the immune system
hinge region
connects light and heavy chains, akkiwing them to open and close
epitope
site on antigen that is recognised by the immune system (antigenic determinant)
Precipitation
antibodies bind to soluble antigens, causing them to become insoluble and precipitate out of solution
Agglutination
antibodies bind to antigens on the surface of cells and form antigen body complexes to clump pathogens together making them more visible to the immune system
Neutralisation of bacterial toxins
antibodies bind to bacterial toxins, blocking action of the toxin
Neutralisation of pathogens
antibodies bind to antigens on pathogen surface, that are required for host cell entry, thus preventing pathogen invasion
Opsonisation
Antibodies bind to pathogen surface antigens to form antigen-antibody complex and tag pathogens for destruction, activating phagocytes and complement proteins, leading to pathogen destruction
Cytotoxic T cells
monitor body cells for the presence on their surface of foreign antigens that have been generated in the body cell by intracellular pathogens, recognise and kill infected host cells by releasing toxic compounds
Active immunity
Develops after the immune system responds to being exposed to microbes or foreign substances
Passive immunity
acquired when antibiotics are transferred from one person to another
Cell mediated adaptive immunity
involves various actions of T cells to eliminate intracellular pathogens
haemolytic disease
mother’s natural active immunity causes her immune system to attack the foetus’s red blood cells
