Neutrophils

Definition

Neutrophils are a type of white blood cell, specifically a granulocyte, that plays a crucial role in the body's immune response by fighting off infections and inflammation. They are the most abundant type of white blood cells, accounting for 50-70% of all leukocytes, and are the first responders to sites of infection or injury. Their primary function is to engulf and destroy pathogens through a process known as phagocytosis, along with releasing enzymes and antimicrobial substances to kill bacteria and fungi.

5 Must Know Facts For Your Next Test

1. Neutrophils are produced in the bone marrow and have a lifespan of only a few hours to a few days in circulation.
2. They are capable of moving through blood vessel walls to reach tissues where they are needed, a process known as diapedesis.
3. Neutrophils contain granules filled with enzymes and antimicrobial agents, which they release to combat invading pathogens.
4. These cells can form neutrophil extracellular traps (NETs) that trap and kill microbes outside of their own cell bodies.
5. A high neutrophil count can indicate an ongoing infection or inflammatory condition, while low levels may suggest an increased risk of infections.

Review Questions

• How do neutrophils contribute to the body's immune response during an infection?
  • Neutrophils play a vital role in the immune response by being among the first cells to arrive at the site of infection. They recognize pathogens through various receptors and initiate phagocytosis, engulfing and destroying the microbes. Additionally, neutrophils release enzymes and antimicrobial substances from their granules to eliminate pathogens effectively. Their rapid response is crucial for controlling infections before they can spread further in the body.
• Evaluate the significance of neutrophils forming extracellular traps (NETs) during the immune response.
  • The formation of extracellular traps (NETs) by neutrophils is significant because it provides a mechanism for capturing and neutralizing pathogens without the need for direct engulfment. NETs consist of strands of DNA and proteins that ensnare bacteria and fungi, preventing them from spreading. This strategy not only helps control infections but also minimizes damage to surrounding tissues by isolating harmful microorganisms. However, excessive NET formation can lead to tissue damage and contribute to inflammatory diseases.
• Synthesize information about how neutrophil levels can affect overall health outcomes in patients.
  • Neutrophil levels are critical indicators of health; elevated counts often signify an active infection or inflammatory response, while low counts can indicate a compromised immune system. In clinical settings, monitoring neutrophil levels can help predict patient outcomes during surgeries or treatments like chemotherapy. High levels may lead to tissue damage due to excessive inflammation, whereas low levels can increase susceptibility to infections, complicating recovery. Thus, maintaining balanced neutrophil levels is essential for optimal health.

Related terms

Phagocytosis: The process by which certain cells, like neutrophils, engulf and digest foreign particles, pathogens, or dead cells.

Granulocytes: A category of white blood cells characterized by the presence of granules in their cytoplasm, which includes neutrophils, eosinophils, and basophils.

Cytokines: Small signaling proteins released by cells that have a specific effect on the interactions and communications between cells, especially in immune responses.