Here are the essential concepts you must grasp in order to answer the question correctly.
Defensins
Defensins are small cationic peptides that play a crucial role in the innate immune response. They are produced by various cells, including epithelial cells and neutrophils, and function primarily by disrupting the membranes of pathogens, such as bacteria and fungi. Unlike phagocytic cells, defensins do not engulf pathogens but instead act as antimicrobial agents that can neutralize them directly.
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Phagocytosis
Phagocytosis is a cellular process in which certain immune cells, such as macrophages and neutrophils, engulf and digest pathogens or debris. This process is a key component of the innate immune system, allowing the body to eliminate harmful microorganisms. Phagocytic cells recognize pathogens through specific receptors, internalize them, and then destroy them using enzymes within specialized compartments called phagosomes.
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First Line of Defense
The first line of defense refers to the body's initial barriers against infection, which include physical and chemical barriers such as skin, mucous membranes, and secretions like saliva and tears. These barriers are designed to prevent pathogens from entering the body. While defensins contribute to the immune response, they are part of the broader innate immune system, which also includes phagocytic cells that act as a second line of defense.
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Introduction to First-Line Defenses