L39: Control Of Breathing Flashcards
(33 cards)
What are the 4 components that control breathing?
1) chemoreceptors for O2 and CO2
2) Mechanoreceptors in the lungs and joints
3) Control centers in the brain (medulla and pons)
4) Respiratory muscles regulated by brain stem receptors
Voluntary control of breathing can be exerted via the **.
Cerebral cortex when breath holding or voluntary hyperventilation
What is the ventral respiratory group?
-Composed of inspiratory and expiratory neurons that are inactive during normal quiet breathing , but active when demands for ventilation are increased
What are the expiratory muscles that the ventral respiratory group stimulate?
Abdominals and intercostal
What is the dorsal respiratory group (DRG)?
Primarily inspiratory neurons that terminate on inspiratory muscles . When they stop firing, inspiratory muscles relax and passive expiration occurs.
What generates respiratory rhythm?
The pre-botzinger complex located in the upper part of the ventrolateral medulla.
What drives the firing rate of the inspiratory neurons in the DRG?
The pre-botxinger complex (PBC)
-Input from peripheral chemoreceptors
What can depress the activity of the PBC?
Drugs such as propofol and opioids
Where is the pneumotaxic center and what does it do?
- In the upper pons
- Turns off inspiration by limiting the burst of action potentials in the phrenic nerve. Limited the size of tidal volume and regulates respiratory rate.
What is apneusis?
An abnormal breathing pattern; prolonged inspiration followed by brief expiratory movement
How does Apneusis happen?
Stimulation of the apneustic center neurons -> excites the inspiratory center in the medulla -> prolonged inspiration
- Prolonged APs in the phrenic nerve result in prolonged diaphragm contraction.
- Ketamine and TBI can cause this.
What does hyperventilation mean for PaCO2 and arterial pH?
Decrease in PaCO2 causing arterial pH to rise.
**this is self limiting because dramatic decrease in PaCO2 causes syncope and reversion back to normal breathing
What is the effect of hypoventilation of PO2?
PaO2 is decreased and PaCO2 is increased, both of which are strong drivers for ventilation.
What do central chemoreceptors primarily sense?
CO2 levels- Goal is PaCO2=40
CO2 can cross BBB where it converted to H+ and HCO3+ resulting in decreased pH and chemoreceptors will HTN signal for hyperventilation
What happens to breathing rate when pH of CSF is decreased?
Breathing rate is increased.
What happens to breathing rate when the pH of the CSF is increased?
The breathing rate is decreased
When is the CO2/ventilation curve shifted to the right (more CO2 is present)?
-during sleep, alcohol, narcotics, and anesthetics because the reticular activating system gets shut off. Ventilation does not change.
What are the most important regulators for breathing control?
Central chemoreceptors
What do peripheral chemoreceptors primarily sense?
O2 levels
Where are peripheral chemoreceptors located?
Carotid and aortic bodies
What do peripheral chemoreceptors do if PaO2 is <60mmHg?
They increase the breathing rate.
What do peripheral chemoreceptors do when there is an increase in PaCO2?
Increase breathing rate, though PCs job in this is less important than its detection by central chemoreceptors
What do peripheral chemoreceptors do when there is a decrease in arterial pH?
Mediated only by the PCs in the carotid bodies, but increase breathing rate.
What kind of receptor are lung stretch receptors, where are they located, what are they activated by, and what does their activation result in?
- Mechanoreceptors
- Located in airway smooth muscle
- activated by distention of lungs and airway
- results in decreased breathing rate by prolonging expiration time
