Responding To Antigens Flashcards
Antigen
Are molecules or parts of molecules that interact with the receptors of lymphocytes and with antibodies and thus initiates an immune response.
Non-self antigens
Antigens that do not belong to an organism’s own cells.
Self antigens
An organism’s own antigens, which are normally don’t initiate a immune response.
Allergen
An antigen that elicits an allergic response.
Immunogens
Antigens that elicit an immune response.
Antibodies
Proteins produced by b lymphocytes that bind to specific antigens.
Pathogen
Agent that causes diseases in organisms
Cellular pathogens
Bacteria, fungi, oomycetes, worms, Arthropods.
Non-cellular pathogens
Viruses, viroids and prions
Physical barriers in animals
Intact skin, epithelial cells in respiratory and gastrointestinal tracts, mucus and cilia.
Chemical barriers in plants
Tannins, caffeine, defensins.
Physical barriers in plants
Thicker cuticle, thick layer of bark, orientation of leaves, stomata closing.
Microbiological barriers
Normal flora found on the skin, mouth, nose, throat and gastrointestinal tract. The presence of normal flora compete with invading bacteria for resources and space, and produce chemicals that reduce environment of the micro- environment.
Macrophages
A type of leukocyte that is responsible for engulfing and digesting foreign matter in the body, as well as damaged cells and the remnants of apoptosis.
Dendritic cells
A type of apc.
Antigen-presenting cell
A cell that uses mhc-11 on it surface to present foreign antigens to helper t lymphocytes to elicit an adaptive immune response.
Complement proteins
Proteins that kill foreign cells by lysis and are activated in response to antigen-antibody complexes.
Neutrophils
Phagocyte
Mast cells
Play a role in inflammation by releasing histamines which cause blood to dilate.
Cytokine examples
Interferons: produced by virus-infected cells and inhibit viral replication by resulting in transcription of antiviral genes and expression of antiviral proteins.
Chemokines: attract white blood cells to the site of infection.
Inflammation
Accumulation of fluid, plasma proteins and leukocytes that occurs when tissue is damaged/ infected. Results in sweeping, heat, pain, renews and loss of function of tissues.
Fever
Increase in body temperature that results in the hypothalamus of the brain being set to a higher level by inflammatory cytokines.
Inflammation steps
- Pathogens breach first line of defence.
- Injured cells release cytokines that attract neutrophils and mast cells that release histamines (blood vessel dilation -> leukocytes and proteins enter infected tissue),platelets close up the wound by releasing clotting factors.
- Neutrophils migrate towards cytokines and are activated causing recruitment of phagocytes -> factors are secreted killing and degrading pathogens.
- Macrophages are activated and secrete cytokines, along with neutrophils debris at the site of infection phagocyte debris.
- Inflammatory response continues until the pathogen is eliminated and wound is healed.
Lymphatic system
Body system transports immune cells (apc) throughout the body, where antigen recognition by lymphocytes occurs.
Primary lymphoid tissues
Bone marrow and thymus
Secondary lymphoid tissues
Lymph nodes, spleen, tonsils, adenoids and the appendix.
B lymphocytes
Lymphocytes that when stimulated produce large quantities of antibodies specific to an antigen. They are responsible for humoral immunity and include both memory and plasma cells.
T helper
Bind to antigen mhc-11 complexes on apc and activate b lymphocytes to secrete antibodies, macrophages to phagocytose and cytotoxic T cells to kill infected cells.
Cytotoxic T cells
T lymphocyte that is stimulated by cytokines to bind to antigen mhc-1 complexes on infected host cells and release cytotoxic compounds to destroy the infected cells.
Memory cells
Activated against specific antigen that remain in the lymphoid tissues for a long time, and permit a faster and more effective secondary response if the same antigen is encountered again.
