Neural and Chemical Control of Respiration Flashcards
What is respiration rate and depth controlled by?
Blood gas concentrations (O2 CO2 and H+) and lung stretch receptors.
What do central chemoreceptors detect? What do peripheral chemoreceptors detect?
Central - high Pco2. CO2 crosses the BBB and generate H+ ions
Peripheral - low Po2 high Pco2 and low pH
What does action potential frequency indicate about eupneic breathing?
Inspiration is active and expiration is passive. The action potentials in the phrenic or external intercostal nerves (from spinal nerve) increase up until the end-inspiratory position. There are very few if any AP’s in the abdominal or internal intercostals.
What does action potential frequency indicate in hyperpnea?
Both inspiration and expiration are active processes.
Descirbe the Hering-Breuer inflation reflex:
During deep inspirations, lung inflation activates stretch receptors that inhibit further inflation via vagal afferents and phrenic efferents. It is not important during eupnea because the lung is not stretched enough.
What does the dorsal respiratory group (DRG) do? It is in the Medulla and located bilaterally in the nucleus of the tracts solitarus
It is probably the initiator of activity of the phrenic nerves innervating the diaphragm. It also receives vagal afferents from the chemoreceptors sensing arterial PCO2, PO2, and pH. It thought to integrate this info in modulating the frequency and depth of breathing
What does the basal respiratory group (VRG) do? It is in the medulla and part of the retrofacial nucleus, nucleus ambiguous, and nucleus retroambifualis.
It consists of both inspiratory and expiratory neurons.
What happens if there is a transection at or below level IV in the medulla?
Apnea results. Therefore the central patter generator (CPG) must be above level IV
What happens if there is a transection at level III in the medulla?
Breathing is rhythmic but consists of a series of irregularly timed gasping efforts. Therefore the central patter generator (CPG) is located between level III and IV but the normal breathing pattern requires input from higher up.
What happens if there is a transection at level II in the medulla?
With vagi intact it is rhythmic and decreased in frequency and tidal volume. With vagi cut apneusis, an abnormal form of breathing occurs.
What happens if there is a transection at level I in the medulla?
With vagi intact breathing is normal. With vagi cut the breathing frequency is reduced but tidal volume increases. Thus feedback to the Pontine respiratory groups (PRG) appears to fine tune the breathing patterns by modulating the frequency and tidal volume of breathing.
What is Cheyne-Stokes respiration?
abnormal pattern of breathing characterized by alternating periods of hyperpnea and apnea.
What is Cluster breathing (Biot’s respiration)?
Result of stroke, head trauma, pressure or a lesion in the lower pontine region of the lower brainstem characterized by closely grouped series of shallow breaths similar in size and separated by apnea
What is ataxic breathing?
an abnormal form of breathing associated with a lesion in the medullary respiratory center characterized by a completely irregular series of inspirations and expirations with pauses and eventually apnea.
What role does alveolar PCO2 have on respiration rate?
It is a major controller of respiration rate. After intense hyperventilation there is a period of apnea because CO2 levels are below normal. Once CO2 levels reach normal, respiratory activity begins. The initial return of breathing is Cheyne-Stokes
