Polymorphonuclear neutrophils (PMNs)

Definition

Polymorphonuclear neutrophils (PMNs) are a type of white blood cell characterized by a segmented nucleus. They are crucial components of the innate immune system, acting as the first line of defense against infections.

5 Must Know Facts For Your Next Test

1. PMNs are the most abundant type of white blood cells in humans, making up about 50-70% of circulating leukocytes.
2. They play a key role in phagocytosis, engulfing and digesting pathogens and cellular debris.
3. PMNs contain granules filled with enzymes and antimicrobial proteins that help kill bacteria and fungi.
4. They are rapidly recruited to sites of infection through chemotaxis, guided by signals such as cytokines and chemokines.
5. PMNs have a short lifespan, typically surviving only a few hours to days once they leave the bloodstream.

Review Questions

Related terms

Phagocytosis:

The process by which cells engulf and digest microorganisms and cellular debris.

Cytokines:

Small proteins released by cells that have a specific effect on interactions and communications between cells.

Chemotaxis:

The movement of an organism or cell toward or away from a chemical stimulus.