Q: Which complement components are activated by Lipid A, and what is their effect?

$$C3a$$ \text{ and } C5a$; they promote inflammation and attract immune cells to the site of infection.

Question 1

Which of the following best describes the primary effect of Lipid A (endotoxin) on the human body, as illustrated in the diagram?

Accepted Answer

It triggers a cascade of immune responses, including cytokine release, inflammation, fever, and can ultimately lead to shock.

Question 2

According to the diagram, which cytokines are released by leukocytes in response to Lipid A, and what is their role?

Accepted Answer

Interleukin 1 (IL-1) and Tumor Necrosis Factor (TNF); they induce fever and promote inflammation.

Question 3

What is the clinical significance of disseminated intravascular coagulation (DIC) as a result of Lipid A activity?

Accepted Answer

DIC leads to widespread blood clotting, which can cause organ failure and severe bleeding due to consumption of clotting factors.

Question 4

Which pathway in the diagram leads directly to shock as a result of Lipid A exposure?

Accepted Answer

Inflammation caused by complement activation and cytokine release.

Question 5

How does Lipid A-induced cytokine release contribute to fever, according to the diagram?

Accepted Answer

Tumor necrosis factor (TNF) and interleukin 1 (IL-1) act on the hypothalamus to increase body temperature.

Question 6

Which of the following best explains why Lipid A can cause a reduction in blood pressure?

Accepted Answer

Cytokine-induced damage to blood vessel walls leads to plasma loss and vasodilation.

Question 7

Which complement components are activated by Lipid A, and what is their effect?

Accepted Answer

$$C3a$$ 	ext{ and } C5a$; they promote inflammation and attract immune cells to the site of infection.

Question 8

A patient with a Gram-negative bacterial infection develops petechiae and low platelet count. Based on the diagram, what is the most likely underlying mechanism?

Accepted Answer

Disseminated intravascular coagulation (DIC) triggered by Lipid A-induced blood clotting reactions.

Question 9

Which of the following is NOT a direct effect of Lipid A as shown in the diagram?

Accepted Answer

Induction of antibody production by B cells.

Question 10

If a new drug could block the action of interleukin 1 (IL-1), which of the following effects of Lipid A would be most directly reduced?

Accepted Answer

Fever and neutrophil migration.

Pathogenic Gram-Positive and Gram-Negative Bacteria: Structure, Pathogenicity, and Clinical Relevance

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