Chapter 39.1 terms Pathogen Infectious disease Koch’s postulates

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?

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 people They disrupt your body’s homeostasis 

Anthrax, Malaria, Athlete’s Foot, HIV, and tapeworm

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 disease Find same pathogen in every case of the disease Isolate pathogen & grow outside of organism Place pure pathogen in a healthy host, disease must be caused Re-isolate pathogen from the new host & show that it is the same as the original 

Good Morning

3. What does it mean to be a “reservoir” of a pathogen? Anything that could harbor a disease and potentially spread it The human body itself is the main source of human diseases People who have the pathogen but are not sick yet are in the “incubation period” 

4. In what ways can infectious diseases be transmitted? Direct contact *common cold, influenza, STDs By an object *bacteria, other microorganisms Through the air (coughing, sneezing) *Streptococcus, measles A vector (intermediate organism) *Malaria, West Nile, Lyme disease, the bubonic plague 

Chapter 39.1 terms… Endemic disease Epidemic Antibiotic

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 virus Bacteria… Most damage done by toxins that are transported to the blood Can inhibit protein synthesis, destroy blood cells and vessels, produce fever, or cause convulsions by damaging the nervous system 

6.Distinguish between the patterns of endemic and epidemic diseases. Diseases that are constantly present in the population Ex: the common cold Epidemic When many people in the same area come down with the disease at the same time Ex: influenza, typhoid fever, etc 

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 example Streptococcus 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! 

Answer questions (1 – 4) on page 1030.

Chapter 39.2 terms Innate immunity Phagocyte Interferon

8. Distinguish between innate and acquired immunity. Innate – the body’s earliest lines of defense and those you were born with Acquired – when your body builds up a resistance to a specific pathogen 

9. How do your skin and body secretions protect you? Mucus – keeps various parts of the body from drying out & traps foreign substances Gastric juice – acidic & destroys pathogens Sweat, tears, saliva – all have lysozyme which breaks down bacterial cell walls 

10. How does inflammation help fight pathogens? Inflammation – redness, swelling, pain and heat to the injured area It begins when damaged tissue cells and basophils release histamine This causes the local blood vessels to dilate, and fluid leaked into the area helps destroy the toxic agents present 

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 phagocytes The infected tissue, all of the dead pathogen, dead WBCs, and body fluids is called PUS 

12. What are interferons? How are they produced and what do they do? Phagocytes alone cannot destroy viruses It itself will get taken over  Interferons: proteins that protect cells from viruses They 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 

Chapter 39.2 terms… Lymph Lymph node Lymphocyte

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 

14. What is the lymphatic system’s job? To help maintain homeostasis by keeping a constant body fluid level To help defend against disease 

15. Describe lymph/tissue fluid, lymph nodes, and lymphocytes. Tissue fluid – the stuff that surrounds all of your cells Made of water & dissolved substances from blood When it enters lymph capillaries it is now called “lymph” This fluid returns to the bloodstream after if has been filtered Lymph nodes – small mass of tissue Contains lymphocytes to filter pathogens from lymph Lymphocytes – a type of WBC that defends against foreign substances 

Continued.. Tonsils – large clusters of lymph tissue Form a protective ring and provide protection against pathogens Spleen – stores lymphocytes, does not filter lymph Destroys bacteria and worn-out RBCs Acts as a blood reservoir Thymus – located above the heart Stores immature lymphocytes until they mature 

16. What two immune responses make up acquired immunity? Antibody immunity Helper 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 again Cell-mediated immunity Cytotoxic 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 

17. Distinguish between T cells and B cells. What do they each do? A type of lymphocyte Produced in the bone marrow and processed in the thymus They activate B cells B cells Become plasma cells or memory cells when activated Plasma cells make antibodies (2000 per second!) Memory cells hang around 

Chapter 39.2 terms… Acquired immunity T cell B cell

18. Describe how allergies and autoimmune disorders might happen. When the immune system overreacts to a harmless substance Mast cells release too much histamine This causes sneezing, mucus production, redness Autoimmune disorders When the immune system attacks its own cells as foreign Ex: Lupus, rheumatoid arthritis, multiple sclerosis 

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? Passive Naturally acquired when antibodies are transferred from mom to baby through the placenta or milk Artificially acquired when antibodies from another person are injected into someone else (ex: snakebite) Active Naturally when a person is exposed to antigens & produces antibodies Artificially when a vaccine induces an immune response (kind of a “preview” for your immune system) 

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 Syndrome Transmitted through blood or body fluids HIV 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 genome For many years it continues to infect other helper T cells, and usually progresses to become AIDS 

Answer questions (1 – 4) on page 1041. The End!