Chapter 15: Immune Response and Defence Against Disease Flashcards
What is an antigen?
A large molecule, usually a protein or polysaccharide, that generates an immune response
What is a pattern recognition receptor?
A cell receptor that recognises molecular patterns commonly shared by a number of pathogens
What is a pathogen-associated molecular pattern (PAMP)?
A broad molecular pattern commonly shared by a number of pathogens
What is an epitope?
A small part of a larger molecule that binds to a receptor site and is antigenic
What is an innate immune response?
A non-specific response to pathogens that are not learned and does not have memory
What is an adaptive immune response?
An acquired immune response; after an initial response to a pathogen, the immune system creates a ‘memory’ that leads to an enhanced response to subsequent encounters with the same pathogen
What is callose?
A polysaccharide formed in plant cell walls in response to injury
What are defensins?
A small, antimicrobial peptide secreted by virtually all plants and animals
What is the complement system?
A number of small proteins found in the blood that, when activated, promote chemotaxis, cell lysis nd phagocytosis
What the first three lines of defemse in vertebrates immune system?
1st - effective surface barriers that reduce the chance of pathogens gaining entry
2nd - inflammation and the complement system (macrophages (innate immune response))
3rd - the adaptive immune response
Where are mucous memebranes present?
Vertebrate respiratory, gastrointestinal and reproductive tracts
How do cilia act as a defense against pathogens entering the body?
Another way to remove mucus is by beating the slender hair-like structures called cilia that line the respiratory tract
What is a lysozyme?
An antibacterial enzyme found in tears, saliva and other body fluids, breaks down the cell wall of certain types of bacteria ad causing them to burst (lyse)
What are macrophages?
A large white blood cell in tissues that phagocytoses pathogens
What are cytokines?
A small signalling molecules that coordinates inflammtion and immune responses, and that lukocytes use to communicate with one another; includes interleukins and interferons
What are mast cells?
A cell located in the tissues, which when activated releases granules containing histamine
What is histamine?
A chemical released by mast cells that increases blood flow and the permeability of capillaries, induces vasodilation
What are prostoglandins?
A group of lipids that can cause vasodilation, fever and pain
What is chemotaxis?
The movement of an organism or cell along a chemical concentration gradient either towards (positive chemotaxis) or away from (negative chemotaxis) the chemical stimulus
What are the two types of leukocytes?
Monocytes and neutrophils
What is a monocyte?
A white blood cell that circulates in the blood and matures when it moves from the blood into the tissues
What is a neutrophil?
A phagocytic leukocyte found in the blood and tissues
What is a phagocyte?
A cell that is capable of phagocytosis; includes macrophages and neutrophils
What is a phagosome?
A membrane-bound vesicle formed around a particle during phagocytosis
What is a phagolysosome?
A membrane-bound vesicle formed from the fusion of a phagosome and lysosome
What is opsonisation?
A process in which a pathogen is coated with antibodies and marked for indegestion and destruction by phagocystosis
What is the membrane attack complex (MAC)?
A complex of complement proteins that forms pores in the membranes of target cels, disrupting the phospholipid bilayer
What are lymphocytes?
A type of leukocyte involved in adaptive immune responses
What is the difference between a B-cell and T-cell
B-cells produce anitbodies while T-cells recognise the anitgen of a specific pathogen
Where do B and T cells orginate?
B cells develop in the bone marrow while T cells originate in the bone marrow but mature in the thymus gland where they are ‘programmed’ to recognise the antigen of a sepcific antigen.
What are the two types of B cells?
Plasma cells and memory cells
What is cell-mediated immunity?
When cytotoxic T cells recognise and destroy virally infected and cancerous cells
What is the thymus gland?
A gland sitting inside the rib cage that is involved in the development of mature T lymphocytes
What are cytotoxins?
A compund released by cytotoxic T cells that kills infected or cancerous body cells
What is the disadvantage of T cells?
These cells cause transplant tissue rejection
What is the function of helper and/ regulatory T cells?
Helper T cells enhance the activity of other immune cellls while regulatory T cells sppress or regulate immune responses
What is passive immunity?
Immunity charcaterised by the transfer of anitbodies from one individual to another; this type of immunity does not show memory
What is an example of passive immunity?
When antibodies are passed from a mother to her foetus through the placenta or during breastfeeding
What is the difference bewteen active and passive immunity?
In active immunity, antigens stimulate the production of antibodies and memory cells are produced, in passive immunity, antibodies are responsible for immunity, no memory cells are produced and immunity begins as soon as the antibodies enter the body
