Explain how what causes fever and how it impacts the homeostatic control body temperature. Be sure to identify the integrator, sensors and effector (s) in your answer.
The correct answer and explanation is:
Correct Answer:
Fever is caused by the presence of pyrogens, which are substances that trigger the hypothalamus to increase the body’s temperature set point. This disrupts homeostatic control of body temperature. In this process, the hypothalamus acts as the integrator, thermoreceptors in the skin and brain serve as the sensors, and the effectors include blood vessels, sweat glands, and skeletal muscles.
300-Word Explanation:
Fever is a temporary rise in body temperature often caused by an infection. It is part of the body’s immune response and is typically triggered by pyrogens, which are substances released by pathogens (exogenous pyrogens) or by the immune system (endogenous pyrogens such as interleukin-1 and tumor necrosis factor). These pyrogens reach the brain and act on the hypothalamus, which is the body’s temperature regulation center.
The hypothalamus functions as the integrator in the feedback system that controls body temperature. Normally, it maintains a set point around 37°C (98.6°F). When pyrogens act on the hypothalamus, they cause the set point to rise. This leads the body to perceive its current temperature as too low, even though it is normal. In response, the hypothalamus initiates mechanisms to raise body temperature.
The sensors in this process are thermoreceptors, located both in the skin and within the hypothalamus itself. These receptors constantly monitor blood and environmental temperature, sending information to the hypothalamus.
The effectors are body systems that help increase temperature. These include:
- Skeletal muscles, which produce heat through shivering.
- Blood vessels, which constrict (vasoconstriction) to reduce heat loss from the skin.
- Sweat glands, which become less active to reduce evaporative cooling.
These responses result in a rise in core body temperature, helping the immune system fight off infection by slowing the reproduction of some pathogens and enhancing white blood cell activity. Once the infection subsides and pyrogens decrease, the hypothalamus resets the set point, and the body initiates cooling mechanisms such as sweating and vasodilation to return to normal.