Type J (juxtacapillary) receptors in the lung parenchyma are stimulated by which conditions and what clinical symptoms do they mediate?

• A Increased lung inflation; mediate Hering-Breuer inflation reflex with apnea
• B Decreased airway caliber; mediate bronchoconstriction and cough reflex
• C Hypercapnia and acidosis; mediate hyperpnea and increased tidal volume
• D Pulmonary edema, microemboli, and inflammatory mediators; mediate rapid shallow breathing and dyspnea ✓

Explanation

J-receptors (or C-fiber endings) are unmyelinated afferents located near the pulmonary capillaries in the interstitium. They are activated by increased interstitial fluid pressure (pulmonary edema), microemboli, chemical mediators (bradykinin, capsaicin), and inflammatory states. Stimulation produces rapid shallow breathing, dyspnea, and the feeling of chest tightness — contributing to the breathing discomfort of pulmonary congestion and pneumonia. They travel via unmyelinated C-fibers in the vagus nerve. The Hering-Breuer reflex is mediated by slowly adapting stretch receptors (SARs) in airway smooth muscle.

Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.

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Written and medically reviewed by the StethoPrep medical team.