fever generation

Definition

Target type: biologicalprocess

The heat generation process that results in a rise in body temperature above the normal, often as a response to infection. [GOC:dph, GOC:jl]

Fever is a complex physiological response to infection or inflammation, characterized by an elevation in body temperature above the normal range. This process involves a coordinated effort between the immune system, the hypothalamus (the body's thermostat), and various signaling molecules.

Here's a breakdown of the key steps involved in fever generation:

1. **Detection of Pathogens:** When pathogens like bacteria, viruses, or fungi invade the body, immune cells, particularly macrophages and neutrophils, recognize these invaders through pattern recognition receptors (PRRs). These receptors bind to pathogen-associated molecular patterns (PAMPs), triggering the release of signaling molecules such as cytokines, including tumor necrosis factor-alpha (TNF-α), interleukin-1 (IL-1), and interleukin-6 (IL-6).

2. **Cytokine Release:** These cytokines travel to the hypothalamus, a region in the brain responsible for regulating body temperature.

3. **Hypothalamus Activation:** Upon reaching the hypothalamus, these cytokines interact with specific receptors, activating the production of prostaglandins, particularly prostaglandin E2 (PGE2).

4. **PGE2 Production:** Prostaglandin E2 (PGE2) is a potent pyrogen (fever-inducing molecule) that acts on the hypothalamus, specifically the preoptic area.

5. **Resetting the Thermoregulatory Set Point:** PGE2 alters the hypothalamic set point for body temperature, causing it to be elevated. This elevation is the core mechanism behind fever.

6. **Physiological Response:** To reach the new, higher set point, the body implements several physiological responses:
* **Vasoconstriction:** Blood vessels in the periphery constrict, reducing blood flow to the skin, minimizing heat loss.
* **Shivering:** Involuntary muscle contractions generate heat.
* **Increased Metabolism:** The body increases its metabolic rate, producing more heat.

7. **Fever Resolution:** Once the infection or inflammation is resolved, cytokine production decreases, and the hypothalamic set point returns to normal. The body then actively dissipates heat through sweating and vasodilation (dilation of blood vessels).

In summary, fever is a complex process involving immune cell recognition of pathogens, cytokine release, hypothalamic activation, prostaglandin production, and a series of physiological responses aimed at increasing body temperature to combat infection. While fever can be uncomfortable, it's an important defense mechanism that helps the body fight off infections.'
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Proteins (2)

Compounds (70)