Control of Ventilation Flashcards
What are the two controls of ventilation?
Neural control
- Role of the brain stem
- Lung receptors and other inputs
Chemical control
- Response to changes in PCO2, PO2 and pH
- The central chemoreceptors
- The peripheral chemoreceptors
What are the components of the brain stem?
Who was Galen, and what was his role?
Galen was a physician for gladiators in the Greek city of Pergamon in the 2nd century.
What did Galen observe when a gladiator’s spine was cut above C3?
Breathing stopped.
What did Galen observe when a gladiator’s spine was cut below C5?
Breathing was unaffected, but there was paralysis in the arms and legs.
What conclusion did Galen draw from his observations about the cervical region of the spine?
He concluded that the cervical region sends essential information for breathing.
What is the significance of the cervical spine in controlling ventilation?
The cervical spine, particularly above C3, is critical for sending signals necessary for breathing.
What is the function of the pneumotaxic center?
The pneumotaxic center inhibits the inspiratory phase.
What is the role of the apneustic center?
The apneustic center prolongs inspiration.
Which 3 structures are located in the medulla and are involved in controlling ventilation?
Bötzinger complex
Nucleus ambiguus
and retro ambiguus
What are the effects of sectioning along specific lines on breathing patterns?
section above the pons = eupnoea, which is the normal pattern of breathing.
section between the pons and medulla = gasping pattern of respiration - however still getting inspiration and expiration.
section across the 4th ventricle = apneusis which is essentially a breath hold.
separate the pons and medulla from the spinal cord = complete apnoea which is complete cessation of breathing.
What are the 4 main respiratory nuclei in the medulla?
Four main respiratory nuclei (groups of cells):
- Dorsal respiratory group (DRG) within the nucleus tractus solitarius (NTS)
- Ventral respiratory group (VRG), containing the nucleus ambiguus (NA) and nucleus retroambigualis (NRA)
- pre-Bötzinger (PBC) and the Bötzinger complex (BC), located near the nucleus retrofacialis (RTN).
Pre-Bötzinger complex thought to be what
key centre of respiratory rhythmogenesis
What type of neurons does the dorsal respiratory group (DRG) contain?
The DRG contains only inspiratory neurons that fire immediately prior to and during inspiration.
What kind of activity do DRG neurons exhibit during inspiration?
They show ramp-like activity, increasing steadily and ceasing abruptly.
What 2 functions are controlled by the DRG?
Controls the depth and rate of breathing.
Provides the basic rhythm/pattern of breathing.
Where is neural activity from the DRG relayed?
phrenic nerves.
which 3 places does the DRG receive input?
Chemoreceptors and lung mechanoreceptors.
Cranial nerves IX (glossopharyngeal) and X (vagus).
Spinal cord and higher brain centers.
How do DRG inspiratory neurons affect other respiratory groups?
They inhibit expiratory neurons in the ventral respiratory group (VRG) and the pontine respiratory group (PRG).
What are the higher centers involved in respiration, and what do they regulate?
Higher centers include temperature and emotion, which influence breathing patterns.
What are the two main respiratory centers in the pons, and their roles?
Pneumotaxic center: Inhibits the inspiratory phase.
Apneustic center: Prolongs inspiration.
What are the respiratory groups located in the medulla, and their functions?
Ventral respiratory group (VRG): Controls respiratory muscles.
Dorsal respiratory group (DRG): Processes sensory input and controls basic respiratory rhythm.
What 4 inputs do lung receptors provide to the respiratory system?
Stretch receptors: Respond to lung expansion.
Irritant receptors: Detect harmful substances.
Juxtapulmonary capillary (J) receptors: Monitor lung volume.
Proprioceptors: Detect muscle load and movement.
How does voluntary breathing influence the respiratory system?
Voluntary breathing is controlled via pyramidal tracts from higher brain centers to respiratory muscles.