Lecture 1 - introduction to the immune system Flashcards
what is the immune system?
the tissues, cells and molecules that protect the body from infection
what is innate immunity?
innate immunity is the early phase of the host response and it is present in all individuals at all times. It does not increase with repeated exposure. it predates separation between animal and plant species and discriminates between groups of pathogens,.
what is adaptive immunity?
adaptive immunity is generated by specific lymphocytes. It discriminates between individual pathogens and is associated with memory. appears abruptly in evolution in the cartilaginous fishes.
where do all cellular elements of the blood arise from?
all cellular elements of the blood, including cells of the immune system arise from pluripotent hematopoietic stem cells in the bone marrow.
what are anatomic barriers as a line of defence?
skin, oral mucosa, respiratory epithelium and intestine
what are complement / antimicrobial proteins as a line of defence?
C3, defensives and regIIIy
what are innate immune cells as a lien of defence?
macrophages, granulocytes and natural killer cells
what are adaptive immunity cells as a line of defence?
B cells/ antibodies and T cells
what happens in the initial immune response ?
The immune response can be broken down into three phases of response to an antigen. The innate phase, the innate response and the adaptive immune response. The first two phases of the immune system rely on the recognition of pathogens via germline-encoded receptors of the innate immune system. Some of the key cells of the innate immune system are macrophages, Eosinophils, Basophils neutrophils, mast cells and dendritic cells; DC cells act as a bridge from the innate immune system to the adaptive immune system. If the innate immune system fails, the adaptive immune system can be used and utilises variable antigen-specific receptors that are produced as a result of segment rearrangements. It is important to note that adaptive immunity occurs with time as the B-cells and T cells specific for the invading pathogen must undergo clonal expansion, before they differentiate into the effector cells to fight at the sit of infectio
How the adaptive and innate immune system linked?
the key cell which links the adaptive and innate immune system is the dendritic cell. When a dendritic cell takes up antigen in the infected tissue, it migrates to the regional lymph nodes where it stimulates naïve T-lymphocytes to activate, proliferate and differentiate the cells
how can macrophages recognise different pathogens?
macrophages express a number of receptors that allow them to recognise different pathogens. for example, mannose receptor, TLR-1: TLR-2 dimer, NOD, gluten receptor, scavenger receptor and TLR-4
explain how infection triggers th inflammatory response
Infection triggers an inflammatory response. Macrophages encountering bacteria in tissues are triggered to release cytokines that increase the permeability of blood vessels and chemokines, which direct the migration of neutrophils to the site of infection. Neutrophils and macrophages are the principal inflammatory cells.
describe the structure of an antibody
has a variable region where the antigen binding site is and the constant region at the bottom where the effector function is.
what are epitopes and paratopes?
epitopes are the sites within antigens to which antibodies bind to and paratope is the variable part of the antibody to which it binds to epitope
how are antigens destroyed?
the antigen must first be broken down into peptide fragments. the epitope peptide binds to a self molecule, an MHC molecule. the T cell receptor binds to a. complex of MHC molecule and epitope peptide
