BIO 311D 2nd Edition Lecture 30 Outline of Last Lecture I. Blood and LymphII. Lymphocyte specializationIII. Action of B and T cells Outline of Current Lecture I. Action of B and T cells in immune responseII. Introduction to neurons and membrane potential Current LectureI. Action of B and T cells in immune response A. All blood cells come from pluripotent stem cells in bone marrow. They differentiate into cells with specific functions. B. Defense systems:1. Innate, non-specifica) Barriersb) Internal inflammation2. Adaptive, specifica) B and T lymphocyte receptors C. Immunoglobulin proteins on surfaces of B cell and T cell recognize specific antigenD. B cells1. “Humoral immunity”- fight antigen in body fluids (blood, lymph)2. Secrete antibody into fluid3. Mature into bone marrowE. T cells1. “Cell-mediated immunity”- fight antigen in cells2. Bind antigen with T cell receptors in membrane3. Mature in thymus gland4. Example: viral infected cells, cancer (tumor cells),autoimmune disorders F. Handout Question 3-57: Cut and splice their DNA. Antibodies,proteins consist of small regions. Set of gene segments 43.13permanently cut DNA to produce particular antibody. Specializebefore exposure, but clone after exposureG. Handout Question 3-58: Clonal selections are the proliferation of a lymphocyte into a clone of cells in response to binding to an antigen. An encounter with an antigen selects which lymphocyte will divide to produce a clonal population of thousands of cells specific for a particular epitope.H. Most of the great diversity of antibodies in a person results from the splicing and rearrangement of which? [IClicker Question and Answer]1. Immunoglobulin proteins during lymphocyte development2. mRNA’s for immunoglobulin proteins during lymphocyte development [secondary] 3. DNA for immunoglobulin proteins during lymphocyte development4. Molecules in specialized lymphocytes after they first encounter their antigen I. After activation by antigen, T cells specialize themselves (and, in strong activation, produce memory cells) Then…1. Helper T cells2. Cytotoxic (Killer) T cells J. If the antigen is in cells, T cells are activated1. To get activated initially, a T cell must be stimulated by an antigen-presenting cell that has BOTH:a) That T cell’s specific antigen ANDb) The persons “Self” MHC 2. How to prevent rejection after organ transplanta) Suppress immune response through corticosteroid hormones 3. Bone Marrow Matching a) Similarities within the MHC K. Helper T cells (once activated by antigen-presenting cell) clone themselves and release chemical signals that stimulate B cells and cytotoxic T cells [releases signals, cytokines, L. B cells T cells Form where? Bone marrow Bone marrowSpecialize? Cut and splice Cut and spliceActivated by? T cells or binding to receptorsAntigen recognition Once activated, what? Secrete antibodies Helper T: activate othersKiller T: killsFor memory cells? Yes YesII. Introduction to neurons and membrane potentialA. Neurons: highly specialized cells, in shape and especially in their membrane proteins. 1. Dendrites receive signals2. Axon conducts signals to other cells3. The cell body contains most cytoplasm and organelles B. A synapse is the gap between two neurons through which they communicate. Each of the 100 million neurons in our brain has hundreds of synaptic connections with other cells C. Ions can be moved across membranes through passive transport (most ion channels in neurons are passive) or active transport (e.g. sodium-potassium pump)1. What determines the direction an ion will move across the membrane through a passive channel?a) Charge gradientb) Concentration
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