Chapter 16, Problem 1ACQ

Figure 16.2 When bacteria are destroyed by leukocytes, pyrogens are released into the blood. Pyrogens reset the body’s thermostat to a higher temperature, resulting in fever. How might pyrogens cause the body temperature to rise?

Summary Introduction

To determine:

The cause of rise in body temperature due to pyrogens.

Introduction:

Pyrogens are the polypeptides that are responsible for increasing the body temperatures, by causing metabolic changes in the body. They can be endogenous or exogenous. The exogenous pyrogens are produced by the cells found in animal body, such as macrophages. The endogenous pyrogens are produced by the infectious organism, such as bacteria.

Explanation of Solution

Fever is the rise in body temperature due to infection. Presence of pyrogens in the blood stream leads to the fever. When an infection attacks the body, then it is combated by the immune system of the body. During this process pyrogens are released. These pyrogens then travel to the hypothalamus via the bloodstream. The hypothalamus is present in the brain and regulates the body temperature. The pyrogens bind to the receptors on the hypothalamus, leading to rise in body temperature. This high temperature of the body opposes the survival of infection causing bacteria.

The most common pyrogen is interleukin-1, which is produced by the WBCs. WBCs when bind to the certain bacteria and viruses, are termed as the macrophages. The main purpose of IL-1 is to signal the T-helper cells to come in action.

Conclusion

The pyrogens rises the body temperature by binding to the receptors on the hypothalamus.