Question 1

Which bacterium grows in the intestines after prolonged antibiotic therapy?

Accepted Answer

Prolonged antibiotic treatment can alter the normal intestinal flora, decreasing its protective activity and leading to the overgrowth of other microorganisms, such as the bacterium C. difficile in the colon. C. albicans can overgrow in the vagina but does not usually cause intestinal issues. Lactobacillus and Helicobacter also do not produce intestinal overgrowth problems with antibiotic use.

Question 2

Which component of the plasma protein system tags pathogenic microorganisms for destruction by neutrophils and macrophages?

Accepted Answer

C3b (a component of the complement cascade) adheres to the surface of a pathogenic microorganism and serves as an efficient opsonin. Opsonins are molecules that tag microorganisms for destruction by cells of the inflammatory system, primarily neutrophils and macrophages. The other options do not accurately identify a component capable of tagging pathogenic microorganisms.

Question 3

What causes the edema that occurs during the inflammatory process?

Accepted Answer

The increased flow and capillary permeability result in a leakage of plasma from the vessels, causing swelling (edema) in the surrounding tissue and is solely responsible for inflammation-induced edema. Vasodilation (increased size of the blood vessels) causes slower blood velocity and increases blood flow to the injured site. Endothelial cell contraction (not expansion) leads to increased capillary permeability. Emigration of neutrophils to the area of infection/injury leads to increased destruction of the offending agent.

Question 4

Some older adults have impaired inflammation and wound healing because of which problem?

Accepted Answer

In some cases, impaired healing is not directly associated with aging, in general, but can instead be linked to a chronic illness such as cardiovascular disease or diabetes mellitus. Older adults may have circulatory problems, but that would not lead directly to impaired inflammation and wound healing. Older people do not have deficient complement and chemotaxis, nor do they have insufficient mast cell numbers.

Question 5

How do surfactant proteins A through D provide innate resistance?

Accepted Answer

The lung produces and secretes a family of glycoproteins, collectins, which includes surfactant proteins A through D and mannose-binding lectin. Collectin binding facilitates macrophages to recognize the microorganism, enhancing macrophage attachment, phagocytosis, and killing. The complement cascade occurs during the inflammatory phase. These proteins do not secrete mucus of synthesize lysosomes.

Question 6

Which secretion is a first line of defense against pathogen invasion that involves antibacterial and antifungal fatty acids, as well as lactic acid?

Accepted Answer

Sebaceous glands in the skin secrete sebum that is made up of antibacterial and antifungal fatty acids and lactic acid that provide the first-line barrier against pathogen invasion. Perspiration, tears, and saliva contain an enzyme (lysozyme) that attacks the cell walls of gram-positive bacteria.

Question 7

What does activation of the classical pathway begin with?

Accepted Answer

Activation of the classical pathway begins only with the activation of protein C1 and is preceded by the formation of a complex between an antigen and an antibody to form an antigen-antibody complex (immune complex). Infection with a virus can lead to the start of the inflammatory process, but is not the specific activation factor. Mast cells release the contents of their granules to initiate synthesis of other mediators of inflammation among other actions. Macrophages are one cell type involved in phagocytosis.

Question 8

Which chemical mediator derived from mast cells retracts endothelial cells to increase vascular permeability and to cause leukocyte adhesion to endothelial cells?

Accepted Answer

The biologic activity of platelet-activating factor is virtually identical to that of leukotrienes; namely, it causes endothelial cell retraction to increase vascular permeability, leukocyte adhesion to endothelial cells, and platelet activation. The other options do not accurately identify the chemical mediator derived from the process described in the question. Chemokines function primarily to induce leukocyte chemotaxis. Prostaglandins interact with the kinin system to stimulate nerve endings and cause pain, among other actions. Bradykinin is the most important product of the kinin system and causes vascular permeability, smooth muscle contraction, and pain.

Question 9

Which chemical interacts among all plasma protein systems by degrading blood clots, activating complement, and activating the Hageman factor?

Accepted Answer

Only plasmin regulates clot formation by degrading fibrin and fibrinogen, and it can activate the complement cascade through components C1, C3, and C5. Plasmin can activate the plasma kinin cascade by activating the Hageman factor (factor XII) and producing prekallikrein activator.

Question 10

In the coagulation (clotting) cascade, the intrinsic and the extrinsic pathways converge at which factor?

Accepted Answer

The coagulation cascade consists of the extrinsic and intrinsic pathways that converge only at factor X.

Question 11

What is the inflammatory effect of nitric oxide (NO)?

Accepted Answer

Effects of NO on inflammation include vasodilation by inducing relaxation of vascular smooth muscle, a response that is local and short-lived, and by suppressing mast cell function, as well as platelet adhesion and aggregation. NO does not increase capillary permeability and cause pain, increase neutrophil chemotaxis and platelet aggregation, or cause smooth muscle contraction and fever.

Question 12

Which action is a purpose of the inflammatory process?

Accepted Answer

If the epithelial barrier is damaged, then a highly efficient local and systemic response (inflammation) is mobilized to limit the extent of damage, to protect against infection, and to initiate the repair of damaged tissue. The response to a specific offending agent is the function of the adaptive immune response. Lysosomes lyse cell membranes. Immunity against a subsequent tissue injury occurs through the action of B cells and T cells.

Question 13

What is the function of opsonization related to the complement cascade?

Accepted Answer

Opsonins are molecules that tag microorganisms for destruction by cells of the inflammatory system (opsonization), primarily neutrophils and macrophages. Opsonization does not process pathogenic microorganisms, destroy glycoprotein cell membranes, or promote anaphylactoxic activity.

Question 14

Frequently when H₁ and H₂ receptors are located on the same cells, they act in what fashion?

Accepted Answer

Both types of receptors are distributed among many different cells and are often present on the same cells and may act in an antagonistic fashion. For instance, neutrophils express both types of receptors, with stimulation of H₁ receptors resulting in the augmentation of neutrophil chemotaxis and H₂ stimulation resulting in its inhibition. The two receptors do not act synergistically, additively, or agonistically.

Question 15

What is an outcome of the complement cascade?

Accepted Answer

The complement cascade can be activated by at least three different means, and its products have four functions: (1) anaphylatoxic activity, resulting in mast cell degranulation, (2) leukocyte chemotaxis, (3) opsonization, and (4) cell lysis. The complement cascade does not activate the clotting cascade, prevent spread of infection, or inactivate chemical mediators.

Question 16

What is the vascular effect of histamine released from mast cells?

Accepted Answer

Histamine, when released from mast cells, causes vasodilation. It does not cause platelet adhesion, initiation of the clotting cascade, or increased endothelial adhesiveness.

Question 17

What process causes heat and redness to occur during the inflammatory process?

Accepted Answer

The increased blood flow as a result of vasodilation and increasing concentration of red cells at the site of inflammation cause locally increased warmth and redness. Platelet aggregation is important in the clotting cascade. Decreased capillary permeability would affect local edema. Endothelial cell contraction leads to increased capillary permeability and the formation of edema.

Question 18

How does the chemotactic factor affect the inflammatory process?

Accepted Answer

Two chemotactic factors, neutrophil chemotactic factor (NCF) and eosinophil chemotactic factor of anaphylaxis (ECF-A), are released during mast cell degranulation. NCF attracts neutrophils (a type of leukocytes), and ECF-A attracts eosinophils to the site of inflammation. The other options do not accurately describe the affect chemotactic factors have on the inflammatory process.

Question 19

What plasma protein system forms a fibrinous meshwork at an inflamed site?

Accepted Answer

The coagulation (clotting) system is a group of plasma proteins that form a fibrinous meshwork at an injured or inflamed site. This protein system (1) prevents the spread of infection to adjacent tissues, (2) traps microorganisms and foreign bodies at the site of inflammation for removal by infiltrating cells (e.g., neutrophils and macrophages), (3) forms a clot that stops the bleeding, and (4) provides a framework for future repair and healing. The complement system, kinins, and fibrinolysis do not form a fibrinous meshwork at an inflamed site.

Question 20

What effect does the process of histamine binding to the histamine-2 (H₂) receptor have on inflammation?

Accepted Answer

Binding histamine to the H₂ receptor is generally antiinflammatory because it results in the suppression of leukocyte function. Binding to H₂ receptors does not cause activation, acceleration, or termination of the inflammatory process.

Quiz 7: Innate Immunity: Inflammation and Wound Healing