Lesson 20: Central Chemoreceptors and Their Functions

Lesson 20: Central Chemoreceptors

• Respond indirectly to PaCO2.

• Located in medulla; stimulate dorsal respiratory center.

• Blood-brain barrier (BBB): selective barrier separating blood from CSF.

  • CO2 diffuses freely; H+ and HCO3- do not.

• CO2 in CSF dissociates into H+ and HCO3-.

• Rising H+ in CSF increases rate and depth of respiration until steady state is achieved (minutes).

Impact of Non-Volatile Acids

• Non-volatile acids (e.g., lactic acid) do not pass through BBB, influencing ventilation (Ve) only long-term.

Hyperventilation and Its Effects

• Therapeutic hyperventilation can reduce intracranial pressure (ICP), effective for hours to ~2 days.

• After that, pH normalizes at pH 7.32 due to bicarbonate transport.

• Central chemoreceptor responds to hypercarbia and hypoxemia but is depressed by excessive levels of both.