What type of receptors are J-receptors and where are they located?

• A. Thermoreceptors found in the skin
• B. Photoreceptors located in the retina
• C. Pressure receptors in the capillaries around alveoli
• D. Mechanoreceptors in the bronchi

Answer: (C)

J-receptors, also known as Juxtapulmonary-capillary receptors, are specialized sensory nerve endings located in the lung tissue near the capillaries around the alveoli. They play a significant role in the pulmonary reflexes, responding predominantly to changes such as increased pulmonary interstitial pressure, excessive fluid accumulation, or pulmonary inflammation. When activated, J-receptors stimulate a reflexive response, often resulting in rapid shallow breathing or a feeling of breathlessness.

The location of J-receptors is critical, as it allows them to monitor the pulmonary capillaries closely for any pathological changes that may affect gas exchange and overall respiratory function. This positioning enables them to react quickly to potentially harmful conditions, maintaining pulmonary homeostasis.

The other options refer to different types of receptors found elsewhere in the body. For example, thermoreceptors are involved in detecting changes in temperature, photoreceptors are responsible for vision in the retina, and mechanoreceptors in the bronchi detect mechanical changes in the airway, but none fulfill the role that J-receptors do in the context of pulmonary function. Understanding the specific characteristics and locations of different receptors helps clarify their physiological functions and responses within the body's systems.