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
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
4. What is the first line of defense for humans/ most animals?
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
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
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
• 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