2 Chapter 39 RQ… What are disease-causing agents called? What procedure is used to identify a pathogen?The common cold is an example of an ___demic disease.What proteins protect cells from viruses?Which cells does HIV kill?
3 1. What is an infectious disease? Caused by disease-causing agents – “pathogens”Examples: bacteria, protozoans, fungi, viruses, worms, etc.They are found in soil, water, animals, and other peopleThey disrupt your body’s homeostasis
4 Anthrax, Malaria, Athlete’s Foot, HIV, and tapeworm
5 2. What procedure is followed to determine what causes a disease? Lots of causes to diseases…Genetic, wear & tear, exposure, malnutrition, pathogens (which cause infectious disease)Koch’s postulates help discover which pathogen causes which infectious diseaseFind same pathogen in every case of the diseaseIsolate pathogen & grow outside of organismPlace pure pathogen in a healthy host, disease must be causedRe-isolate pathogen from the new host & show that it is the same as the original
8 3. What does it mean to be a “reservoir” of a pathogen? Anything that could harbor a disease and potentially spread itThe human body itself is the main source of human diseasesPeople who have the pathogen but are not sick yet are in the “incubation period”
10 4. In what ways can infectious diseases be transmitted? Direct contact*common cold, influenza, STDsBy an object*bacteria, other microorganismsThrough the air (coughing, sneezing)*Streptococcus, measlesA vector (intermediate organism)*Malaria, West Nile, Lyme disease, the bubonic plague
12 5. How do viruses and bacteria cause symptoms of a disease? Cause damage by taking over a cell’s DNA and organelles to make the cell make more virusBacteria…Most damage done by toxins that are transported to the bloodCan inhibit protein synthesis, destroy blood cells and vessels, produce fever, or cause convulsions by damaging the nervous system
14 6.Distinguish between the patterns of endemic and epidemic diseases. Diseases that are constantly present in the populationEx: the common coldEpidemicWhen many people in the same area come down with the disease at the same timeEx: influenza, typhoid fever, etc
16 7. In what ways can infectious diseases be treated? Fight bacterial diseases with antibiotics (NO effect on viruses… )Continued use of antibiotics has caused bacterial resistance – penicillin exampleStreptococcus pneumoniae is now penicillin-resistant (it causes pneumonia, ear infections, and meningitis)There are anti-viral drugs, but our best defense is our own immune system!
20 8. Distinguish between innate and acquired immunity. Innate – the body’s earliest lines of defense and those you were born withAcquired – when your body builds up a resistance to a specific pathogen
21 9. How do your skin and body secretions protect you? Mucus – keeps various parts of the body from drying out & traps foreign substancesGastric juice – acidic & destroys pathogensSweat, tears, saliva – all have lysozyme which breaks down bacterial cell walls
22 10. How does inflammation help fight pathogens? Inflammation – redness, swelling, pain and heat to the injured areaIt begins when damaged tissue cells and basophils release histamineThis causes the local blood vessels to dilate, and fluid leaked into the area helps destroy the toxic agents present
24 11. Distinguish among the white blood cell types and describe their functions. White blood cells –Phagocytes – destroy pathogens by engulfing them. They include…- Monocytes which mature into macrophages, neutrophils, and eosinophils*macrophages (which are in body tissues) are the first defense, which then consume all pathogens & damaged cells- neutrophils (which circulate in the blood) come next- new tiny monocytes squeeze into the area & mature into phagocytesThe infected tissue, all of the dead pathogen, dead WBCs, and body fluids is called PUS
26 12. What are interferons? How are they produced and what do they do? Phagocytes alone cannot destroy virusesIt itself will get taken over Interferons: proteins that protect cells from virusesThey are host-cell specific (can only protect human cells)It is produced by a body cell that has been infected – the message goes to non-infected cells, who then produce antiviral proteins
29 Your cells have MHC markers that are specific to you (nametags ) 13. How does the immune system recognize cells that belong to you, and those that don’t?Your cells have MHC markers that are specific to you (nametags )Your immune system recognizes substances that enter your body as foreign by the protein markers (antigens) on their surfaces
33 15. Describe lymph/tissue fluid, lymph nodes, and lymphocytes. Tissue fluid – the stuff that surrounds all of your cellsMade of water & dissolved substances from bloodWhen it enters lymph capillaries it is now called “lymph”This fluid returns to the bloodstream after if has been filteredLymph nodes – small mass of tissueContains lymphocytes to filter pathogens from lymphLymphocytes – a type of WBC that defends against foreign substances
35 Continued.. Tonsils – large clusters of lymph tissue Form a protective ring and provide protection against pathogensSpleen – stores lymphocytes, does not filter lymphDestroys bacteria and worn-out RBCsActs as a blood reservoirThymus – located above the heartStores immature lymphocytes until they mature
37 16. What two immune responses make up acquired immunity? Antibody immunityHelper T cells (made in bone marrow & matured in the thymus) activate…B cells which become either plasma cells…that make antibodies AND memory B cells that stay in the bloodstream in case the infection strikes againCell-mediated immunityCytotoxic T cells (stored in the lymph nodes, spleen, and tonsils) differentiate & clone, then…travel to the infection site and…Release enzymes directly into the pathogens, who then die
41 17. Distinguish between T cells and B cells. What do they each do? A type of lymphocyteProduced in the bone marrow and processed in the thymusThey activate B cellsB cellsBecome plasma cells or memory cells when activatedPlasma cells make antibodies (2000 per second!)Memory cells hang around
44 18. Describe how allergies and autoimmune disorders might happen. When the immune system overreacts to a harmless substanceMast cells release too much histamineThis causes sneezing, mucus production, rednessAutoimmune disordersWhen the immune system attacks its own cells as foreignEx: Lupus, rheumatoid arthritis, multiple sclerosis
46 19. What is the difference between passive and active immunity 19. What is the difference between passive and active immunity? How can you acquire these?PassiveNaturally acquired when antibodies are transferred from mom to baby through the placenta or milkArtificially acquired when antibodies from another person are injected into someone else (ex: snakebite)ActiveNaturally when a person is exposed to antigens & produces antibodiesArtificially when a vaccine induces an immune response (kind of a “preview” for your immune system)
48 20. Overview the history of HIV and AIDS, and describe how it impacts the immune system. Human Immunodeficiency Virus kills helper T cells and leads to Acquired Immune Deficiency SyndromeTransmitted through blood or body fluidsHIV is a retrovirus. It attaches to the receptor on a helper T cell, enters, and uses reverse transcriptase to write it’s RNA into DNA and become part of the host cell genomeFor many years it continues to infect other helper T cells, and usually progresses to become AIDS
49 Answer questions (1 – 4) on page 1041. The End!