1 / 34

Chapter 43

Chapter 43 The Immune System. Chapter 43. Immune system. Innate Immunity. Is a response to invading pathogens. The response is based on the recognition of molecules characteristic of the pathogen.

eserrano
Download Presentation

Chapter 43

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 43 The Immune System Chapter 43 Immune system

  2. Innate Immunity • Is a response to invading pathogens. • The response is based on the recognition of molecules characteristic of the pathogen. • These associated molecule patterns AMP’s) are recognized by receptors that are either soluble or located on the surface of blood cells.

  3. Signal transduction pathways are triggered upon AMP binding to these receptors. • This rapid response releases a number of signal molecules into the environment. • DEFENSINS class of signal molecules that expose “+” chrged amino groups on their surface which bind to the exposed “-” chrged amino’s on a bacterial membrane surface.

  4. INTERFERON  signal molecule released by almost all cell types in the body upon viral infection. These molecule, signals adjacent, uninfected cells to degrade their RNA and block protein production. • Although a death sentence for the cells, this stops the spread of the infection

  5. Innate Immunity and phagocytes • Non-specific phagocytes attack pathogens in tissues. These cells circulate through the body and are known as leukocytes. There are 3 major types: • Neutrophils • Macrophages • NK’s

  6. Neutrophil

  7. Macrophage Macrophage

  8. Blood fluke in liver of mouse eosinophils and macrophages

  9. Dentritic cell

  10. Inflammatory Response • Certain infected or injured cells release chemical alarm signals. • These signals promote dilation of blood vessels and permeability of capillaries.

  11. II. Acquired Immunity Lymphocytes are the body’s 2nd major defense, triggered by the phagocytes release of cytokines • Any foreign molecule that initiates a response from a lymphocyte  antigen • Lymphocytes recognize and bind to a small portion of the antigen  epitope

  12. Lymphocytes • B lymphocytes (B cells) and T lymphocytes (T cells) circulate through the blood and lymph. • Concentrated in the spleen and lymph tissues • Each lymphocyte recognizes a particular epitope via an antigen receptor  displays specificity

  13. B cell’s • The principal function of B cells is to make and secrete antibodies against specific antigens. • Binding to an antigen, among other signals, initiates a signaling pathway that leads to the production of plasma cells that secrete antibodies specific for the epitope. • This response is referred to as HUMORAL IMMUNITY

  14. B cell receptors • “Y” shaped molecule with 2 identical antigen-binding sites that attach to antigens through non-covalent bonding. • Can recognize and bond to antigens on the surface of the microbe cell (intact) or those that are released from microbes in solution.

  15. T cells • Do not secrete antibodies but instead regulate the immune responses of other cells or directly attack the cells that carry the specific antigens. • This response is referred to as  CELL MEDIATED IMMUNITY • T cells are either CYTOTOXIC T or HELPER T’s.

  16. T cell receptors for antigens • T cell receptors are composed of parallel chains linked together. • Recognize small fragments of antigens bound to normal cell surface proteins MHC • This process is called antigen presentation

  17. B cell

  18. Cell mediated immunity • Although B cells are capable of recognizing epitopes of an intact antigen that may or may not be a protein, T cells recognize only the peptide fragment of a protein antigen. • This fragment must be bound to a self protein on the surface of the body’s cells MHC’s

  19. MHC’s • MHC proteins on cells serve as self-markers, to enable an individuals immune system to distinguish it’s own cells from those that are foreign. • MHC I – • Found on all nucleated body cells • Bind foreign antigen peptides that have been synthesized within the cell. • MHC I molecules are recognized by specific T’s called  cytotoxic T’s

  20. MHC II – • Synthesized by antigen presenting cells, B cells and macrophages. • Bind peptides from foreign materials that have been internalized and fragmented. • MHC II molecules are recognized by helper T’s.

  21. Cytotoxic T’s • Activated cytotoxic T’s recognize “altered-self” cells, particularly those that are virally infected or tumor cells. • When recognized that will induce apoptosis.

  22. Cytotoxic T

  23. Helper T’s • When activated, secrete proteins known as  CYTOKINES • Cytokines bind to specific cell receptors, particularly of the immune system to promote their activation.

  24. Clonal selection The selection of a lymphocyte to a particular antigen activates the division and differentiation of that cell. • Primary immune response occurs upon 1st time exposure. • Illness occurs because only a few cells are present that can recognize epitopes. • Secondary immune response occurs thereafter.

  25. Clones of memory cells are produced during a primary immune response. • Upon repeated exposure to an antigen, memory cells are more rapidly activated than native cells.

More Related