Deck 15: Nonspecific Host Defense Mechanisms

Question 1

Which of the following function as opsonins?
a. antibodies
b. antigens
c. complement fragments
d. both a and c

Answer 1

Opsonins are substances which enables the phagocytes to attach themselves to the encapsulated pathogens. They can be antibiotics or complimentary fragments. Antibiotics attach to the capsules. After this, the phagocytes can attach to the pathogens as they can recognize the receptors on the surface of the pathogen. Likewise complimentary fragments also deposit on the surface of the capsule of the pathogens. Because of these receptors in the surface of the pathogen, the phagocytes can attach themselves to the pathogens. Hence, the correct option is (d) .
Antibodies also function as opsonins. But this is not the only substance that functions as the opsonins. Hence, the option (a) is incorrect.
Antigens do not function as opsonins but they bind to the specific antibody. They are originated from inside the body or from outside. Antigens produced inside the body are tolerated by the immune system of the body. But the antigens that come from outside are attacked and neutralized. Hence, the option (b) is not correct.
The option (c) is incorrect because the compliment fragments are not the only opsonins but there are other substances that function as opsonins.
Hence, the correct option is (d)

Question 2

Which of the following statements about interferons is false?
a. Interferons are virus-specific.
b. Interferons have been used to treat hepatitis C and certain types of cancer.
c. Interferons produced by a virus-infected cell will not save that cell from destruction.
d. Interferons produced by virus-infected rabbit cells cannot be used to treat viral diseases in humans.

Answer 2

Interferons are proteins produced by cells which are infected by virus. They are antiviral in nature. They inhibit the growth of virus in the host. These Interferons are not virus-specific as they act against a variety of viruses not a particular type of virus. But they are host-specific. They are effective only in the host in which it is produced. Hence, the option (a) is the correct option.
Interferons are experimented for the treatment some viral infections and cancers. Interferons are produced in the industries by genetically engineered bacteria. Genetically engineered bacteria are bacteria in which human interferon genes are inserted. So, they are used to treat hepatitis C and certain types of cancer. This is a true statement. Hence, the option (b) is not correct.
Interferons produced by a virus-infected cell. The infernos get released from the infected cell and attach with the membranes of the adjacent cells and inhibit the virus from spreading into those cells. But they will not save that cell from which it was produced from destruction - It is a true statement. Hence the option (c) is not correct.
Viral diseases in humans cannot be treated with Interferons produced by virus-infected rabbit cells. This is because; the Interferons are specific to the species from which it is produced. They are not effective in other species.This is a true statement. Hence, the option (d) is not correct.
Hence, the correct option is (a)

Question 3

Which of the following is not one of the four cardinal signs or symptoms of inflammation?
a. edema
b. heat
c. loss of function
d. redness

Answer 3

Inflammation is a normal response of the body to any local injury or irritation or microbial invasion. It consists of series of events like vasodilation, increase in permeability of capillary walls, accumulation of leukocytes in the site of injury and so on. Inflammation also shows certain symptoms and signs like redness, heat and edema in the site of injury. Loss of function is the not a cardinal sign of inflammation. Edema due to inflammation may interfere with the bending of particular joint, but it does not cause loss of function. Hence, the correct option is (c) .
Edema is one of the cardinal sign of inflammation. Edema occurs in the site of injury due to the collection of plasma. Plasma collects into the surrounding cells around the site of injury. This makes the site to get swollen. Hence, the option (a) is incorrect.
Heat is also one of the symptoms of inflammation. It is due to the dilation of vessels at the site of injury. As the capillaries get dilated, the vasoactive agents like histamine and prostaglandins are released at that site by the injured cells. Increased blood flow to that site of injury causes heat in that site. Also, the metabolic activities of cells are increased at that site. This also adds to that heat. Hence, option (b) is incorrect.
Redness is a cardinal sign of inflammation. Redness is caused due to the increased blood flow into that site due to vasodilation. Hence, the option (d) is incorrect.
Hence, the correct option is (c)

Question 4

Host defense mechanisms-ways in which the body protects itself from pathogens-can be thought of as an army consisting of how many lines of defense?
a. two
b. three
c. four
d. five

Question 5

Which of the following is not part of the body's first line of defense?
a. fever
b. intact skin
c. mucus
d. pH of the stomach contents

Question 6

Each of the following is considered a part of the body's second line of defense except:
a. fever.
b. inflammation.
c. interferons.
d. lysozyme.

Question 7

Which of the following is not a consequence of activation of the complement system?
a. attraction and activation of leukocytes
b. increased phagocytosis by phagocytic cells (opsonization)
c. lysis of bacteria and other foreign cells
d. repair of damaged tissue

Question 8

Each of the following is a primary purpose of the inflammatory response except:
a. to localize the infection.
b. to neutralize any toxins being produced at the site.
c. to prevent the spread of microbial invaders.
d. to stimulate the production of opsonins.

Question 9

Which of the following cells is a granulocyte?
a. eosinophil
b. lymphocyte
c. macrophage
d. monocyte

Question 10

All the following would be considered an aspect of microbial antagonism except:
a. competition for nutrients.
b. competition for space.
c. production of bacteriocins.
d. production of lysozyme.