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The Body Systems. The Immune System. What is a system?. A group of tissues (organs) that work together to do a certain task. Ex) digestive system, circulatory system, immune system… Function of the immune system is to protect your body from invasion of pathogens. “The War on Pathogens”.

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The Body Systems


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    1. The Body Systems

    2. The Immune System

    3. What is a system? • A group of tissues (organs) that work together to do a certain task. • Ex) digestive system, circulatory system, immune system… • Function of the immune system is to protect your body from invasion of pathogens.

    4. “The War on Pathogens” • Your body is always surrounded by pathogens • Viruses, bacteria, fungi, etc. • Germ theory—infectious diseases are caused by microorganisms of different types • Diseases can be passed from one person to the next are called infectious or communicable

    5. Structure of a Virus • Virus- a microscopic particle made of nucleic acid and proteins that invades and takes over cells • Relative virus size • 100% of viruses are pathogenic!!!!

    6. Made of: nucleic acid (DNA or RNA) surrounded by a protein coating (capsid). Structure of a Virus (cont.)

    7. Viral Replication • Parasites (dependent on host for replication) • Steps of viral replication: 1.) Recognition of marker protein on specific cell types. 2.) Attachment 3.) Injection (of nucleic acid) 4.) Assembly 5.) Lysis- cell bursting

    8. Recognition and Attachment

    9. Injection

    10. Replication

    11. Lysis

    12. Characteristics of Living Things • Homeostasis- maintaining stable internal conditions • Metabolism- using energy to build up or break down substances • Reproduction • Made of cells • Genetic material • VIRUSES ARE NOT LIVING THINGS! • ***No metabolism, homeostasis, reproduction, or cells

    13. Replication Cycles of Viruses:2 Types • Viruses have either a lysogenic or lytic replication cycle: • Lytic- replication cycle in which the virus genetic material quickly takes over cell, then lysis occurs to release newly made viruses. • Influenza and Ebola

    14. Lytic Viruses

    15. Lysogenic Viruses • Lysogenic- replication cycle in which virus nucleic acid “fuses” with the host cell’s until lysis (bursting) LATER. • When infected cell undergoes cell cycle: • replication of virus DNA with cell DNA • many cells infected • During this “dormant” period no illness is seen • HIV and herpes

    16. Lysogenic Virus

    17. Protection Against Viruses • ANTIBIOTICS DON’T WORK ON VIRUSES!!! • Vaccines: • Used as PREVENTION, NOT A CURE! • Only useful against viruses that do not mutate and evolve (change) rapidly. • HIV, common cold viruses and flu virus- DNA mutates rapidly. No permanent vaccine! • Tamiflu is an antiviral medicine, but not reliable.

    18. HIV • Devastating Africa • 30 million + people have the disease • Infects T cells – cells of immune system that control the entire immune process • Can lie dormant in our DNA for 10 years + • Ryan White

    19. HIV Dormancy • During dormancy, people look healthy, but can still spread the disease by: • Sexual contact (including oral) • Sharing needles • Blood transfusions • Organ transplant • Baby to mother • Blood to blood contact of any kind • HIV video clip

    20. Other Viral Diseases • Common cold • Chicken pox • Measles • Rabies • Rubella • Mumps • Influenza (flu) • Small pox • Hepatitis • Yellow fever • Ebola

    21. Non-Specific Defense • Your body has several defense mechanisms to keep them out….. FIRST LINE OF NON-SPECIFIC DEFENSE 1) skin 2) sweat 3) mucous membranes 4) saliva SECOND LINE OF NON-SPECIFIC DEFENSE • Inflammatory response

    22. First Line: Skin • Physical barrier • Chemical barrier- secretes oil, sweat, and tears • Sheds constantly (1 million cells per hour)

    23. First Line: Mucus Membranes • These line the inside of all body openings. • Nostrils, mouth, lungs, etc. • Cells of mucus membranes: • secrete mucus that traps foreign objects • lined with hairs called cilia. • Stomach also has acid

    24. Second Line of Defense: Inflammatory Response • The first line of defense has been broken… • SECOND LINE OF DEFENSE ACTIVATED: damaged cells release chemical messages that trigger a series of reactions by body-histamine 1.) capillaries to swell puffiness 2.) increases blood flow to infected area redness 3.) temperature in area rises 4.) pain 5.) phagocytes called in get rid of pathogens ***Sometimes this response is NOT enough…

    25. Immune System Immune System Non-specific Defense First line: Skin Sweat Mucous Stomach acid Second line: Inflammatory Response and Phagocytes

    26. What if pathogens circulate through your body? • White blood cells have to take over. • White blood cells = “soldiers” of your immune system.

    27. The Immune ResponseSpecific Defense • Body’s attack against a pathogen that made it past the “front lines.” • Results in “immunity” because your immune response creates memory cells SPECIFIC for each pathogen. • Chicken pox

    28. IMMUNE RESPONSE SPECIFIC SECOND LINE OF DEFENSE: INFLAMMATORY RESPONSE NON-SPECIFIC FIRST LINE OF DEFENSE: SKIN, MUCOUS, SWEAT

    29. IMMUNE RESPONSE SPECIFIC SECOND LINE OF DEFENSE: INFLAMMATORY RESPONSE NON-SPECIFIC FIRST LINE OF DEFENSE: SKIN, MUCOUS, SWEAT

    30. IMMUNE RESPONSE SPECIFIC SECOND LINE OF DEFENSE: INFLAMMATORY RESPONSE NON-SPECIFIC FIRST LINE OF DEFENSE: SKIN, MUCOUS, SWEAT

    31. IMMUNE RESPONSE SPECIFIC SECOND LINE OF DEFENSE: INFLAMMATORY RESPONSE NON-SPECIFIC FIRST LINE OF DEFENSE: SKIN, MUCOUS, SWEAT

    32. Organs of the Immune System • White blood cells are called leukocytes • Made in the thymus (T cells) and bone marrow (B cells) • Stored in tonsils, spleen, and lymph nodes.

    33. “The Soldiers”White Blood Cells • Leukocytes • Macrophages • Helper T cells • Killer T cells • B cells • Suppressor T cells • Memory cells

    34. How does your body know there is an invader? • All pathogens have “distinct” marker proteins that are antigens. • Antigens -anything that causes an immune response. • Your body must recognize antigens as FOREIGN (NON-SELF) in order to create an immune response. • Recognition video

    35. Step #1 “Invader Identification”Movie • Macrophages identify pathogen as non-self, eat it, display the antigen, and signal for helper T cells. • Interleukin-1 signal released= fever

    36. Helper T cells “signal” for the production of other leukocytes by releasing of interleukin 2. • The next type of leukocytes called to work are known as B cells and Killer T cells.

    37. Step #2 “Cloning Phase” • Many helper T cells, B cells and killer T cells produced • After B cells called up by helper T’s, they begin to produce lots of antibodies

    38. What are antibodies? • Millions of antibodies are made by B cells • How millions are made • They are like “keys” and are specific to each antigen which are like the “locks” • Mark pathogen for death and can also prevent virus attachment to cell

    39. Step #3 “The Attack Phase” • Pathogens marked with antibodies are destroyed by macrophages. • Killer T cells destroy any infected body cell. Movie

    40. Step #4 “Memory Phase” • Macrophages act as the clean up crew, eating pathogens, damaged body cells, etc. • Suppressor T cells “call off the troops” They suppress, or weaken, the attack • Powerful memory T and B cells are left behind to “remember” the attack and quickly recognize a pathogen if it re-enters the body

    41. Immune System Immune System Non-specific Defense Specific Defense= Immune Response Reaction to specific antigen First line: Skin Sweat Mucous Stomach acid Second line: Inflammatory Response and Phagocytes Macrophage signal Helper T cells B cells: Antibodies and Memory Cells Killer T cells signal

    42. Primary vs. Secondary Immune Response Primary response Secondary response • Primary: 1st time in contact with pathogen so takes longer for attack • Secondary: come into contact with a pathogen you’ve already encountered • Memory B cells are there to produce antibodies quickly and in greater amounts

    43. Active vs. Passive Immunity • Active Immunity (immune response, vaccine) • The body ACTIVELY produces its own antibodies • Passive Immunity (breast milk) • Get antibodies from mother’s milk

    44. Immune System FailureAllergies • Allergy: Immune system response against a NON-PATHOGENIC antigen. • Food, pollen, bee stings, dust mites

    45. Immune System FailureAllergies • Body produces more antibodies than you need, which causes release of histamine: • blood vessel dilation • swelling • Antihistamines are in allergy medicine that reduce swelling. • Asthma • Movie

    46. Immune System FailureAutoimmune disease • Immune system fails to distinguish self from non-self • Body makes antibodies against and attacks own cells • Examples: MS (attack nerve cells) Lupus (attacks organs) Rheumatoid arthritis (attacks joints)

    47. Immune System FailureCancer • One major job of the immune system is immunological surveillance. • Killer T cells destroy our cancerous cells. • Immune system fails to locate and remove cancerous cell, & it multiplies to form a tumor. • Malignant tumor spreads, benign does not

    48. AIDSAcquired Immunodeficiency Syndrome • Sometimes the immune system collapses totally. • HIV (Human Immunodeficiency Virus) invades helper T cells with its RNA • B cells and killer T cells not stimulated to work—immune system breaks down! • Body overwhelmed with pathogens • Us: DNA  RNA  PROTEIN • HIV: RNA INJECTED DNAenters host cell DNA to make use of cell machinery • HIV infection video