Acute Phase Response

Definition

The acute phase response is a rapid, non-specific, systemic reaction of the body to various forms of injury, infection, or inflammation. It is a critical component of the innate immune system's initial defense against threats to the body's homeostasis.

5 Must Know Facts For Your Next Test

1. The acute phase response is triggered by the release of inflammatory cytokines, such as interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor (TNF).
2. This response leads to the production of acute-phase proteins, including C-reactive protein (CRP), serum amyloid A, and fibrinogen, which help to fight infection and promote tissue repair.
3. The acute phase response also involves changes in the body's temperature, hormone levels, and metabolism, as well as the activation of the complement system and the coagulation cascade.
4. The acute phase response is a protective mechanism that helps to limit the spread of infection, neutralize pathogens, and initiate the healing process.
5. Prolonged or excessive activation of the acute phase response can contribute to the development of chronic inflammatory diseases, such as rheumatoid arthritis and cardiovascular disease.

Review Questions

• Explain the role of the acute phase response in the innate immune system's initial defense against threats to the body's homeostasis.
  • The acute phase response is a critical component of the innate immune system's initial defense against threats to the body's homeostasis. When the body is exposed to injury, infection, or inflammation, the release of inflammatory cytokines triggers a rapid, non-specific, systemic reaction. This response leads to the production of acute-phase proteins, which help to eliminate pathogens, neutralize enzymes, and initiate tissue repair. The acute phase response also involves changes in the body's temperature, hormone levels, and metabolism, as well as the activation of the complement system and the coagulation cascade. By mobilizing these various physiological and immunological mechanisms, the acute phase response helps to limit the spread of infection and promote the healing process, thereby protecting the body's homeostasis.
• Analyze the relationship between the acute phase response and the barrier defenses described in Section 21.2 of the textbook.
  • The acute phase response is closely linked to the barrier defenses discussed in Section 21.2 of the textbook. The barrier defenses, such as the skin, mucous membranes, and various chemical and cellular mechanisms, provide the first line of defense against pathogens and other threats. When these barriers are breached, the acute phase response is triggered, mobilizing a rapid, systemic reaction to contain the infection or injury and initiate the healing process. The acute-phase proteins produced during the response can enhance the effectiveness of the barrier defenses by neutralizing enzymes, activating the complement system, and promoting the recruitment and activation of immune cells. Additionally, the changes in temperature, hormone levels, and metabolism associated with the acute phase response can further support the barrier defenses in their efforts to maintain the body's homeostasis. Therefore, the acute phase response and the barrier defenses work in tandem to protect the body from external and internal threats.
• Evaluate the potential consequences of a prolonged or excessive activation of the acute phase response, and discuss how this might impact the body's overall health and well-being.
  • While the acute phase response is a crucial mechanism for the innate immune system's initial defense against threats to the body's homeostasis, a prolonged or excessive activation of this response can have detrimental consequences. Sustained high levels of inflammatory cytokines and acute-phase proteins can contribute to the development of chronic inflammatory diseases, such as rheumatoid arthritis and cardiovascular disease. The changes in temperature, hormone levels, and metabolism associated with the acute phase response can also become maladaptive if the response is not properly regulated. For example, the increased metabolic rate and energy demands can lead to muscle wasting and fatigue, while the altered hormone levels can disrupt the body's endocrine system. Additionally, the activation of the complement system and coagulation cascade can result in tissue damage and increased risk of thrombosis if left unchecked. Therefore, it is crucial to maintain a balanced and well-regulated acute phase response to ensure the body's overall health and well-being. Prolonged or excessive activation of this response can have far-reaching consequences and may require medical intervention to restore the body's homeostasis.

Related terms

Inflammation: A localized protective response of the body to injury or infection, characterized by redness, swelling, heat, and pain.

Cytokines: Small signaling proteins released by various cells, including immune cells, that play a crucial role in coordinating the body's response to infection and inflammation.

Acute-Phase Proteins: A group of proteins synthesized by the liver in response to inflammatory cytokines, which help to eliminate pathogens, neutralize enzymes, and initiate tissue repair.