1. Communication between cells Starter: grab a pen, here’s a quick quiz

2. Objectives Describe structure of T and B lymphocytes. Describe the significance of cell signalling and how its done

3. B-Lymphocytes: Lymphocytes which mature in the bone marrow and then migrate to the lymph nodes T-Lymphocytes:Lymphocytes which migrate to the thymus gland for a period of maturation before migrating to the lymph nodes Lymphocytes:Small leucocytes with little cytoplasm and spherical nuclei, which originate from stem cells in the bone marrow Mature lymphocytes circulate in the spleen, lymph nodes, adenoids and tonsils, as well as the lymphatic system and general circulation of the blood Lymphocytes can only be activated by one particular antigen B cells produce antibodies

4. More About T-Lymphocytes Helper T-cells: Help the humoral response by involvement in the maturation of B cells and by triggering the production of antibodies by B-cells SIGNAL Helper T-cell B-cell Antigen

5. Killer T-cells These cells bind onto the pathogenic or infected cells that are presenting the targeted antigens and attack & lyse them.

6. What B cells divide into: Plasma cell – manufactures antibodies Memory cell – Immunological memory (remembers antigens)

7. Cell signalling Because there are so many different cells involved in the immune response they need to be able to communicate with one another. This is known as cell signalling. Have a look at p.171 to appreciate how many cell types there are and why its so important.

8. Cell signalling So, how is it done? 1.Cell-surface molecules 2.Cytokines (like hormones) These bind to surface receptors on the target cell and elicit a response.

9. What information is communicated? Identification: ANTIGENS ON A PATHOGEN TELL YOUR IMMUNE SYSTEM ITS FOREIGN.

10. What information is communicated? Sending distress signals: WHEN YOUR CELLS ARE DAMAGED BY A PATHOGEN, PART OF THE PATHOGEN CELL ENDS UP ATTACHED TO THE HOST CELL MEMBRANE. This is seen as a signal of distress from the immune system or can tell killer T cells to destroy the host cell.

11. What information is communicated? Antigen presentation: 1. Virus attaches to and enters host cell 2. Viral DNA causes host cell to express viral anitgens on its surface 3. Killer T-cell attaches to viral antigen on infected cell 4. Killer T-cell induces death of infected cell

12. Have a look at this http://www.youtube.com/watch?v=PsmS1iH7rlQ http://www.youtube.com/watch?v=wX22y9rz4wU

13. Your turn There’s quite a lot to take in here. What I suggest you do is spend the rest of this lesson reading through p.171 and creating a flow diagram, cartoon strip, information poster for next year’s Y12….. It’s a little ‘year 9’ish but if it works, it works!