Respiration Regulation Flashcards
What are the 3 main respiratory centers in the brainstem?
- Medullary centers (DRG, VRG), 2. Apneustic center (pons), 3. Pneumotaxic center (pons)
What is the function of the Dorsal Respiratory Group (DRG)?
Generates basic rhythm of inspiration (via phrenic nerve to diaphragm)
How does the Ventral Respiratory Group (VRG) differ from DRG?
Active during forced expiration (innervates internal intercostals/abdominal muscles)
What is the role of the apneustic center?
Promotes prolonged inspiration by stimulating DRG (inhibited by pneumotaxic center)
How does the pneumotaxic center regulate breathing?
Inhibits apneustic center → limits inspiration → increases respiratory rate
What are the 2 main chemoreceptors for respiration?
- Central (medulla, sensitive to CSF [H+]), 2. Peripheral (carotid/aortic bodies, sensitive to PaO2, PaCO2, [H+])
What stimulates central chemoreceptors?
Increased CO2 (via conversion to H+ in CSF) - 80% of chemoreflex response
What stimulates peripheral chemoreceptors?
Hypoxia (PaO2 <60mmHg), Hypercapnia (PaCO2 >40mmHg), Acidosis (↑[H+])
What is the Hering-Breuer reflex?
Inflation reflex: Stretch receptors in lungs → inhibit inspiration via vagus nerve
What are the afferent nerves for the cough reflex?
Irritant receptors in airways → vagus nerve → medullary centers
How does exercise increase ventilation?
- Central command (cortex), 2. Proprioceptors, 3. Thermal/chemical changes
What happens to respiration in metabolic acidosis?
Hyperventilation (Kussmaul breathing) to ↓PaCO2 and compensate for ↑[H+]
Why doesn’t hypoxia stimulate ventilation until PaO2 <60mmHg?
Hemoglobin remains >90% saturated above this; peripheral chemoreceptors only respond to dissolved O2
What is Ondine’s curse?
Failure of automatic breathing during sleep due to medullary center damage
How do opioids depress respiration?
Inhibit pneumotaxic center + chemoreceptor sensitivity → ↓respiratory rate
