Chemical regulation of respiration is controlled by central and peripheral chemoreceptors. Central chemoreceptors are located in the medulla and are sensitive to increased hydrogen ion concentration and carbon dioxide levels in the cerebrospinal fluid. When carbon dioxide levels rise in the blood, it crosses the blood-brain barrier and forms carbonic acid, releasing hydrogen ions that stimulate the central chemoreceptors. Peripheral chemoreceptors are located in the carotid bodies and aortic arch and respond to decreases in oxygen, sensing hypoxia.

1. Chemical regulation of
respiration(physiology)

2. Chemical regulation
uDone by chemoreceptors
uRespond to hypoxia ,
hypercapnia , increased H ion
conc
uAre of 2 types
u Central and peripheral

4. CENTRAL
CHEMORECEPTORS
uSituation= DEEPER PARTS OF
MEDULLA
uClose to DRG neurons
uCHEMOSENSITIVE AREA (behind BBB)
uSensitive to increase in H+ ions
uH+ IONS CANNOT CROSS

6. CENTRAL
CHEMORECEPTORS
uDetect CO2 changes
uCO2 dependent respiratory
regulation
uSensitive to CO2 in blood
uDirectly stimulated by H+ in CSF

7. INCREASE IN CO2 AND H+
only CO2 can cross BBB
CO2 reacts with water
CARBONIC ANHYDRASE
forms carbonic acid

8. Splits into H+ and HCO3-
H+ ions stimulate the central chemoreceptors
BBB
CO2,H+
BLOOD VESSEL
CO2 + H2O
H2CO3 H+ + HCO3-
Central chemoreceptors
surrounded by CSF
activate

13. Peripheral
chemoreceptors
uStimulus+ hypoxia
uOxygen sensors in carotid
and aortic bodies; glomus
cells
u3-5 mm size