Central chemoreceptor

Template:Short description Central chemoreceptors are chemoreceptors beneath the ventral surface of the medulla oblongata which are highly sensitive to pH changes of nearby cerebrospinal fluid (CSF). The functional significance of the receptors is indirect monitoring of blood levels of CO₂, thus providing an important parameter for the regulation of ventilation to the nearby respiratory center. Central chemoreceptors are the primary generator of regulatory feedback information for respiration while blood gas levels are around normal.

Peripheral chemoreceptors meanwhile also directly monitor blood O₂.

Anatomy

Central chemoreceptors are located in the so-called chemosensitive area, a bilateral region of the ventrolateral medulla oblongata situated 0.2 mm beneath the ventral surface of the medulla, near the origins of cranial nerves IX and X from the brain. The chemoreceptors relay sensory information to the respiratory center.

Physiology

It is thought that Template:Chem2 may be the only direct stimulus detected by the receptors; the receptors are thought to sense the concentration of CO₂ indirectly by detecting Template:Chem2 formed as reacts with water to form carbonic acid which in turn dissociates to form Template:Chem2 and HCO₃⁻. However, because the gaseous CO₂ from blood far more readily diffuses across the blood–brain barrier to reach the medullary interstitial fluid than Template:Chem2 ions, the chemoreceptors are far more responsive to blood CO₂ concentration changes than to Template:Chem2 concentration changes.

Blood CO₂ is the primary parameter for biological regulation of respiration because its concentration is inversely related to pulmonary ventilation; blood O₂ concentration is meanwhile normally adequate for tissue perfusion across a wide range of ventilatory circumstances (from below 50% of normal to over 2,000% of normal) and is therefore requires less stringent control.

See also

• Chemoreceptors
• Vasomotor center

External links

• Overview at cvphysiology.com