Final answer:
Mucous secretions contain mucin, a protein that thickens mucus to trap particles and microorganisms. Lysozyme, defensins, and IgA help to defend the body in these secretions. Mucous membranes and cilia work together to remove trapped pathogens.
Step-by-step explanation:
Mucous secretions contain mucin, a complex glycoprotein that increases the viscosity of mucus to effectively trap inhaled dust, dirt particles, microorganisms, and pollen. Moreover, mucous secretions are an integral part of our immune system, comprising various substances that defend against infectious agents such as lysozyme (an antibacterial enzyme), defensins (antimicrobial proteins), and immunoglobulin A (IgA), a type of antibody.
The mucous membranes of our body, including those in the respiratory, gastrointestinal, urinary, and reproductive tracts, secrete this protective mucus. Additionally, the cilia present in the lungs, nasal cavity, and other mucosal tissues help in sweeping away the mucus, trapping pathogens, and expelling them from the body. Secretory IgA plays a crucial role in this defense by trapping pathogens in mucus, ensuring they are eliminated from the body.