Learning Path
Question & Answer1
Understand Question2
Review Options3
Learn Explanation4
Explore TopicChoose the Best Answer
A
The body produces heat to directly kill pathogens
B
Immune cells release pyrogens that signal the hypothalamus to raise the body's temperature
C
Increased metabolism from the infection generates excess heat
D
The body absorbs heat from the external environment to combat the infection
Understanding the Answer
Let's break down why this is correct
Answer
When a pathogen enters the body, infected cells and immune cells release cytokines such as interleukin‑1, tumor necrosis factor and interferon. These cytokines act as pyrogens that travel to the hypothalamus and stimulate the production of prostaglandin E₂. Prostaglandin E₂ changes the hypothalamic thermostat, raising the body’s temperature set point. The brain then signals the body to conserve heat and increase heat production, producing a fever. For example, when a bacterial infection releases IL‑1, the hypothalamus raises the set point from 37 °C to 39 °C, causing the body to generate and retain more heat.
Detailed Explanation
Immune cells release small proteins called pyrogens. Other options are incorrect because The belief that the body simply makes heat to kill germs misses the signal step; Infection does raise metabolic activity, but the fever is not just a side effect.
Key Concepts
Innate Immune Responses
Fever Mechanism
Immune Signaling
Topic
Innate Immune Responses
Difficulty
medium level question
Cognitive Level
understand
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