Chemical Controls of Respiration

1. Chemoreceptors (CO2, O2, H+)
1. central chemoreceptors - located in the medulla
2. peripheral chemoreceptors - large vessels of neck
2. Carbon Dioxide Effects
• a powerful chemical regulator of breathing by increasing H+ (lowering pH)
1. hypercapnia Carbon Dioxide increases ->
• Carbonic Acid increases ->
• pH of CSF decreases (higher H+)>
• DEPTH & RATE increase (hyperventilation)
2. hypocapnia - abnormally low Carbon Dioxide levels which can be produced by excessive hyperventilation; breathing into paper bag increases blood Carbon Dioxide levels
3. Oxygen Effects
1. aortic and carotid bodies - oxygen chemoreceptors
2. slight Ox decrease - modulate Carb Diox receptors
3. large Ox decrease - stimulate increase ventilation
4. hypoxic drive - chronic elevation of Carb Diox (due to disease) causes Oxygen levels to have greater effect on regulation of breathing
4. pH Effects (H+ ion)
• acidosis - acid buildup (H+) in blood, leads to increased RATE and DEPTH (lactic acid)
5. Overview of Chemical Effects
• Chemical Breathing Effect
• increased Carbon Dioxide (more H+) increase
• decreased Carbon Dioxide (less H+) decrease
• slight decrease in Oxygen effect CO2 system
• large decrease in Oxygen increase ventilation
• decreased pH (more H+) increase
• decreased pH (less H+) decrease

Category: Physiology Notes