University:
Western Sydney University
Course:
MEDI 2003 | Clinical Sciences 2
Academic year:

2024
Views:

353

Pages:

1
Author:

Mariam A. A.

Central Chemoreceptors Overview Location and Function: Central chemoreceptors (CCR) are located in the medulla, near the ventrolateral surface, close to the cerebrospinal fluid (CSF). They respond primarily to changes in the concentration of CO₂ and the resulting pH changes in the CSF. Mechanism: Increased levels of CO₂ in the blood (hypercapnia) lead to an increase in CO₂ in the CSF. CO₂ in the CSF combines with water to form carbonic acid (H₂CO₃), which dissociates into hydrogen ions (H⁺) and bicarbonate (HCO₃⁻). This increase in H⁺ concentration leads to a decrease in pH, which is detected by the central chemoreceptors. Response to Hypercapnia: The CCRs stimulate the respiratory centers in the medulla, increasing the rate and depth of breathing (hyperventilation) to expel CO₂ and restore normal levels. This process is fine-tuned by the pneumotaxic center, which regulates the transition between inhalation and exhalation. Respiratory Centers Involvement: Pre-Bötzinger Complex: Initiates spontaneous respiration. Botzinger Complex: Involved in the rhythm of expiration. Ventral Respiratory Group (VRG): Contains neurons for both inspiration and expiration. Dorsal Respiratory Group (DRG): Mostly controls inspiration. Inspiration and Expiration Regulation: The VRG sends signals to inspiratory muscles via motor neurons in the spinal cord (C₃-C₅ segments for the diaphragm via the phrenic nerve). Inspiratory neurons in the VRG stimulate muscles like the diaphragm and external intercostal muscles for inhalation. Expiratory neurons facilitate the relaxation of these muscles, leading to exhalation. Apneustic Center: Prolongs inhalation and provides input for breath-holding and the intensity of breathing efforts. Pneumotaxic Center: Regulates the switch-off point of inspiration, thus controlling the breathing rate. Clinical Relevance: Dysfunction in these systems can lead to conditions like apnea or abnormal breathing patterns. CO₂ sensitivity is crucial for maintaining homeostasis; any impairment can disrupt the balance, leading to respiratory acidosis or alkalosis.