Review Questions

1. Why is iron metabolism important in body defenses?

2. How do phagocytes get into tissues during an inflammatory response?

3. Describe how the skin protects against infection.

4. What are the benefits of saliva in protection against infection? What factors found in saliva aid in protection?

5. Name two categories of cytokines and give their effects.

6. Contrast the classical and alternative pathways of complement activation.

7. How does the activation of a few molecules in early stages of the complement cascade result in the cleavage of millions of molecules of later ones?

8. How do complement proteins cause foreign cell lysis?

9. Describe three mechanisms of triggering inflammation. 10. Describe the purpose of apoptosis.

Multiple Choice

1. Lysozyme does which of the following:

A. disrupts cell membranes

B. hydrolyzes peptidoglycan

C. waterproofs skin

D. propels gastrointestinal contents

E. propels the cilia of the respiratory tract

2. The hematopoietic stem cells in the bone marrow can become which of the following cell types?

4. monocyte 5. macrophage

A. 2, 3 B. 2, 4 C. 2, 3, 4, 5 D. 1, 4, 5 E. 1, 2, 3, 4, 5

3. All of the following refer to the same type of cell except A. macrophage B. neutrophil

4. Toll-like receptors are triggered by all of the following compounds except

A. peptidoglycan B. glycolysis enzymes C. lipopolysaccharide

D. flagellin E. certain nucleotide sequences

5. A pathogen that can avoid the complement component C3b would directly protect itself from

A. opsonization B. triggering inflammation C. lysis

D. inducing interferon E. antibodies

6. Which of the following statements about phagocytosis is false?

A. Phagocytes move toward an area of infection by a process called chemotaxis.

B. The vacuole in which bacteria are exposed to degradative enzymes is called a phagolysosome.

C. Phagocytes have receptors that recognize complement proteins bound to bacteria.

D. Phagocytes have receptors that recognize antibodies bound to bacteria.

E. Macrophages die after phagocytizing bacteria but neutrophils regenerate their lysosomes and survive.

7. All of the following cell types are found in a granuloma except A. neutrophils B. macrophages

C. giant cells D. T cells

8. All of the following trigger inflammation except

A. engagement of toll-like receptors.

B. activation of complement.

C. interferon induction of antiviral protein synthesis.

D. tissue damage.

9. Which of the following statements about inflammation is false ?

A. Vasodilation results in leakage of blood components.

B. The process can cause damage to host tissue.

C. Neutrophils predominate at the site during the early stages of acute inflammation.

D. Apoptosis induces inflammation.

E. The cardinal signs of inflammation are redness, swelling, heat, and pain.

10. The direct/immediate action of interferon on a cell is to

A. interfere with the replication of the virus.

B. prevent the virus from entering the cell.

C. stimulate synthesis of antiviral proteins.

D. stimulate the immune response.

E. stop the cell from dividing.

Applications

1. Physicians regularly have to treat recurrent urinary tract infections in paralyzed paraplegic patients. What explanation would the physician provide to a patient who asked why the condition keeps coming back in spite of repeated treatment?

2. A cattle farmer sees a sore on the leg of one of his cows. The farmer feels the sore and notices that the area just around the sore is warm to the touch. A veterinarian examines the wound and explains that the warmth may be due to inflammation. The farmer wants an explanation of the difference between the localized warmth and fever. What would be the vet's explanation to the farmer?

Critical Thinking

1. A student argues that phagocytosis is a wasteful process because after engulfed organisms are digested and destroyed, the remaining material is excreted from the cell (see figure 15.9). A more efficient process would be to release the digested material inside the cell. This way, the material and enzymes could be reused by the cell. Does the student have a valid argument? Why or why not?

2. According to figure 15.11 any cell infected by viruses may die due to the action of interferons. This strategy, however, seems counterproductive. The same result would occur without interferon—any cell infected by a virus might die directly from the virus. Is there any apparent benefit from the interferon action?

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