Unit 11: The Immune System

• lymphocytes: WBC
• innate immunity: non-specific, non-adaptive, rapid response to pathogens
• adaptive immunity: the immune system's response to a specific pathogen
• What is another name for adaptive immunity?

  Acquired immunity
• lysosomes: enzymes that break down bacterial cell walls
• hemocytes: white blood cells that are found in the blood and lymph
• plasmodium: a hemocyte that releases chemicals to kill malaria
• phagocytosis: the process by which a cell engulfs and digests a particle
• mucus: fluid that traps pathogens
• toll-like receptor: a type of protein that recognizes pathogens and triggers an immune response by binding to molecules that are specific to pathogens
• phagocytic cell: WBC
• neutrophil: WBCs that are attracted by signals from infected tissues and engulf invader
• macrophage: a type of white blood cell that engulfs and digests foreign material
• dendritic cells: stimulate adaptive immunity by interacting with other cells
• eosinophils: WBC that contribute to defense by discharging destructive enzyme
• natural killer cells: WBC that release chemicals that lead to cell death, not engulf
• lymphatic system: network that distributes fluid that carries invader
• lymph: fluid that carries white blood cells around the body
• interferons: proteins that interfere with infection
• how do interferons work?

  virus-infected cells secrete interferons to induce nearby un-affected cells to secrete anti-microbial substances
• complement system: group of proteins that activate once it interacts with microbes
• histamine: signaling molecules stored in mast cells responsible for dilation of BV and increasing permeability and swelling
• cytokines: chemical messengers that trigger immune responses and help cells communicate with each other
• enhanced blood flow delivers antimicrobial peptides
• pus: WBC and dead pathogens
• systemic response: the body's response to a stimulus that is delivered throughout the body
• antigen: a specific part of a pathogen
• epitope: small portion of antigen that binds to antigen receptor
• each B cell antigen receptor has 2 heavy and 2 light chains
• C region: constant region with little variety of amino acid sequences
• V region: large variety of amino acids
• antibodies: soluble form of receptor
• how many binding sites are there on a B cell?

  2
• what is connecting the two regions (V and C) on a b cell?

  disulfide bridge
• what is the general pathway of B cell antigen receptors and antibodies?

  B cell releases antibodies to attach to the epitopes on the antigen
• T cells have a chain and B chain linked by disulfide bridge
• how many binding sites are there on a T cell?

  1
• where are the constant regions on B and T cells?

  they are anchoring the entire binding site to the membrane
• Major histocompatibility complex (MHC) molecule: host protein that displays antigen fragment
• what is the general pathway of recognition of protein antigens by T cells?

  pathogen infects host, host's enzyme cleave pathogen into smaller antigen fragments, which binds to MHC molecule. This MHC molecule goes up to the surface and displays the antigen on the cell surface for the T cell to attach