Question

Which mechanism best describes the process by which neutrophils are recruited by endothelial cells?

Answer 1

Neutrophils are recruited by endothelial cells through chemotaxis, where they follow the gradient of chemical signals to the site of infection, adhere to the endothelium, and then undergo diapedesis to enter the tissue and phagocytose pathogens.

Step-by-step explanation:

The mechanism by which neutrophils are recruited by endothelial cells to the site of infection or tissue damage is known as chemotaxis. This process involves several steps:

1. Endothelial cells and other cells at the site of injury release chemical signals, such as leukotrienes and cytokines, which serve as chemoattractants for neutrophils.
2. Leukocytes, including neutrophils, respond to these chemoattractants and move toward the highest concentration of these chemicals.
3. The neutrophils then adhere to the endothelial cells lining the blood vessels and squeeze through the blood vessel wall, a process called diapedesis or extravasation.
4. Once in the tissue, neutrophils phagocytose pathogens and may release enzymes that can damage tissue during the inflammatory response.

Through positive chemotaxis, neutrophils move toward the area of infection, following the gradient of chemical signals becoming more concentrated as they get closer to the source.