Hlenu

Hlenu is a term used in several Slavic languages to denote mucus or sputum produced by the lining of the respiratory tract. In medical contexts it refers to the viscid secretions that are coughed up or expectorated, and which can vary in amount and consistency depending on health and disease.

Mucus is produced mainly by goblet cells in the airway epithelium and by submucosal glands. It consists largely of water, mucins (glycoproteins), salts, and small amounts of enzymes and antibodies. The secretions also contain immune cells and proteins that help defend the airways. Normal mucus helps humidify inhaled air, trap particles, and facilitate their removal from the lungs.

Functions of hlenu include acting as a physical barrier that humidifies and protects the airway, trapping dust, microbes, and irritants, and enabling their clearance through coughing or ciliary action. The biochemical components, such as mucins and antimicrobial proteins, contribute to local immune defense.

Clinical relevance is most evident when mucus production changes. Hypersecretion occurs in conditions such as bronchitis, asthma, chronic obstructive pulmonary disease, and infections. The appearance of hlenu—for example, color, thickness, or volume—can reflect inflammation or infection, but color alone is not a definitive indicator of a particular pathogen. In suspected infection or lung disease, analysis of a sputum sample may include microscopy, culture, or molecular tests to identify organisms or assess inflammatory cells.

Collection and analysis typically involve a spontaneously produced sputum sample or induced sputum, obtained with appropriate precautions and processed in a laboratory to aid diagnosis and treatment planning.