BIOL 125 Final: Review for Chapter 49. The Immune System of Animals

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BIOL 125
Matthew Nelson

Biology 125 Chapter 49. The Immune System of Animals (Review for the Final) 1. What are the two main types of immunity? How are they different? • Innate Immunity: a set of nonspecific defenses against pathogens that exists before exposure to an antigen and involves mast cells, neutrophils, and macrophages; typically results in an inflammatory response • Acquire Immunity: a set of defenses against a particular pathogen or other antigen conferred by antibodies and activated B and T cells following exposure to the antigen; is characterized by specificity 2. Know the basics of arthropod immune system • Barrier defense • Phagocytic cells: Hemocytes • Antimicrobial compounds oToll receptors: release antimicrobial peptides, non-specific defense, specific compounds 3. What is LAL? What is it used for? • LAL, limulus amoebocyte lysate, is found in horseshow crabs; it is produced in response to endotoxin which causes hemolymph to clot/seal off the wound Non-Specific 4. What is the first line of defense for humans/ most animals? • Skin 5. In what ways does the skin act as a barrier? • The skin provides a tough physical barrier and offers a chemical deterrent o Oil secreted by skin cells is converted to fatty acids by bacterial cells which are non-pathogenic; fatty acids lower the skin surface’s pH to around 5 which prevents the growth of most bacterial species • Bodies of insects and animals with exoskeletons are covered with a tough layer called a cuticle with an additional layer of wax that makes it tough for pathogens to enter 6. What are neutrophils? How do they work? • Neutrophils: a type of leukocyte that can move though body tissues and kills invading cells via phagocytosis; can also secrete various compounds that attack bacteria and fungi • common white blood cell (60-70% of white cells), respond to cellular signals released by infected cells, responds by engulfing microbes, very expendable (constantly recyclable) 7. What are basophils? • 0.5% of leukocytes, effective for allergies, they degranulate and release chemical signals (histonine) to initiate inflammation 8. What are eosinophils? • 2-5% of white cells, effective against multicellular threats 9. What are monocytes? • 5% of white cells, have a single nucleus, migrate into the tissues and develop into macrophages which kill microbes 10. What are macrophages? How do they work? • Macrophage: a type of leukocyte that can move through body tissues that engulfs and digests pathogens and other foreign particles; can also send signals to other immune system cells 11. What are NK cells? How do they work? • NK cells: aka natural killer cells, are a type of lymphocyte and part of the innate immune system; controls several types of tumors and microbial infections by limiting their spread and subsequent tissue damage o Activate the death receptor cells which program cell death o Recognize infected cells directly o Mature in bone marrow, lymph nodes, thymus, and the spleen 12. Discuss how an inflammatory response happens • Inflammatory response: an aspect of the innate immune response, seen in most cases of infection or tissue injury, in which the affected tissue becomes swollen, red, and painful (i) bacteria and other pathogens enter the wound (ii) platelets from blood release blood-clotting proteins at wound site (iii) injured tissues and macrophages at the site release cytokines, which recruit immune system cells to site (iv) mast cells at the site secrete factors that constrict blood vessel at wound but dilate blood vessels near wound (v) Neutrophils arrive and begin removing pathogens by phagocytosis (vi) Some newly arrived leukocytes mature into macrophages that phagocytize pathogens and secrete key cell-cell signals 13. How does an inflammatory response help fight an infection? • The site of inflammation becomes swollen (increased number of cells and fluids in the area), red and warm (increased blood flow) and painful (signals from pain receptors); sometimes, a person’s core body temperature may rise above 37.5 oThis increases the rate at which the body’s immune cells can function and reproduce; a fever is thought to be able to harm certain pathogens 14. What is a systematic inflammatory response? • Severe infection or tissue damage • # of leukocytes goes way up in a short time • Fever: develops in response to large presence of microbes, resets body’s thermostat • Sepsis: occurs in response to a large infection (ex. bacteria in bloodstream), capillary beds are dilating where blood pressure drops 15. What are interferons? • Antiviral proteins, secreted by virus-infected cells • Prevent the spread of viruses from cell to cell • Activate natural killer cells and macrophages • Used in
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