Fever

Definition

Fever is an increase in body temperature that typically occurs as a physiological response to infection, inflammation, or other illness. It serves as a vital defense mechanism in the innate immune response, enhancing the body's ability to fight off pathogens by creating an unfavorable environment for their survival and boosting the efficiency of immune cells.

5 Must Know Facts For Your Next Test

1. Fever is generally defined as a temporary increase in body temperature, often above 100.4°F (38°C), and is usually a symptom of an underlying condition.
2. The hypothalamus plays a key role in regulating body temperature and responds to pyrogens by increasing the temperature set point.
3. A moderate fever can enhance immune function, such as increasing the production of white blood cells and improving the activity of certain immune cells.
4. Not all fevers are harmful; mild to moderate fevers can be beneficial in fighting infections, while extremely high fevers may lead to complications.
5. Fever can be associated with various conditions, including infections (viral or bacterial), autoimmune diseases, and even some cancers.

Review Questions

• How does fever function as a component of the innate immune response?
  • Fever acts as an important aspect of the innate immune response by creating an environment that is less favorable for pathogens while enhancing the performance of immune cells. The increased body temperature can inhibit the growth and reproduction of certain bacteria and viruses, making it harder for them to thrive. Moreover, fever promotes the activation and proliferation of various immune cells, such as lymphocytes and macrophages, which are crucial for combating infections.
• Discuss the role of pyrogens in the development of fever and how they influence the hypothalamus.
  • Pyrogens are substances that trigger fever by signaling the hypothalamus to raise the body's temperature set point. When pathogens invade, immune cells release pyrogens like interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-α). These signals prompt the hypothalamus to induce heat production through mechanisms such as increased metabolic rate and shivering while also reducing heat loss through vasoconstriction, leading to an elevated body temperature that characterizes fever.
• Evaluate the potential benefits and risks associated with fever during an immune response.
  • Fever can offer several benefits during an immune response, including enhancing immune cell activity and creating conditions less favorable for pathogens. However, it also carries potential risks; excessively high fevers can lead to febrile seizures in children or damage to body tissues. In severe cases, uncontrolled fever may result in dehydration or exacerbate underlying health conditions. Therefore, while mild to moderate fevers generally support recovery from infection, it's essential to monitor their severity and manage any associated complications.

Related terms

Pyrogens: Substances that induce fever by triggering the hypothalamus to raise the body's temperature set point.

Cytokines: Small proteins released by cells that have a significant role in cell signaling and can promote fever by stimulating the immune response.

Innate Immunity: The first line of defense against pathogens, consisting of physical barriers and immune responses that are non-specific and immediate.