Question

When bacteria are destroyed by leukocytes, pyrogens are released into the blood. Pyrogens reset the body's thermostat to a higher temper ature, resulting in fever. How might pyrogens cause the body temper ature to rise?

Short answer

Answer: The process involves 5 steps: 1. Define Pyrogens - substances typically produced by bacteria or pathogens that cause fever. 2. Explain the Role of the Hypothalamus - acts as the body's thermostat and regulates temperature. 3. Describe the Interaction between Pyrogens and the Hypothalamus - pyrogens interact with the hypothalamus, triggering a series of biochemical reactions. 4. Describe the Role of Prostaglandins - hormone-like substances that regulate the set point of the body's thermostat and signal the body to increase its temperature. 5. Explain the Mechanisms of Fever Development - the body initiates warming mechanisms such as shivering, vasoconstriction, and increasing basal metabolic rate to achieve the new set point and develop a fever.

Step-by-step solution

Define Pyrogens

Pyrogens are substances, typically produced by bacteria or other pathogens, that can cause fever. These molecules can affect the body's temperature-regulating system and lead to an increase in body temperature. In this exercise, we will discuss how pyrogens interact with the body's thermostat and result in fever.

Explain the Role of the Hypothalamus

The hypothalamus is a region of the brain that regulates many of the body's physiological processes, including body temperature. It acts as the body's thermostat by receiving information from temperature receptors located throughout the body. In response to this information, the hypothalamus can either initiate cooling mechanisms (such as sweating) or warming mechanisms (such as shivering) to maintain the optimal body temperature.

Describe the Interaction between Pyrogens and the Hypothalamus

When bacteria or other pathogens are destroyed by leukocytes, pyrogens are released into the bloodstream. These pyrogens travel to the hypothalamus and interact with specific receptors on the surface of hypothalamic cells. This interaction triggers a series of biochemical reactions within the hypothalamus, ultimately leading to the production of prostaglandins.

Describe the Role of Prostaglandins

Prostaglandins are hormone-like substances that play a crucial role in regulating the set point of the body's thermostat. When prostaglandins are produced, they bind to specific receptors in the hypothalamus and raise the set point, thereby signaling the body to increase its temperature.

Explain the Mechanisms of Fever Development

Once the thermostat's set point has been raised by prostaglandins, the body initiates various warming mechanisms in order to achieve the new, higher set point. These mechanisms may include: 1. Shivering: The repeated contraction and relaxation of muscles generate heat. 2. Vasoconstriction: The constriction of blood vessels near the skin's surface reduces heat loss to the environment. 3. Increasing basal metabolic rate: The body accelerates metabolic processes to generate more heat. As these mechanisms take effect, the body's temperature rises to match the new set point. This increase in body temperature, or fever, can help the body fight off infections more effectively. Once the infection has been cleared, the level of pyrogens decreases, the hypothalamus resets the thermostat's set point to its normal level, and the body returns to its regular temperature.