Chapter 8: Control of Ventilation Flashcards
Where does the normal rhythmic pattern of breathing originate?
Brainstem
When do expiratory neurons fire? Significantly, when do they not fire?
During forceful breathing. The expiratory area of the medulla is quiescent during quiet breathing.
Where is the pneumotaxic center located?
Upper pons
What facet of breathing does the pneumotaxic center regulate?
Appears to “switch off” or inhibit inspiration - this regulates inspiratory volume, and secondarily, respiratory rate
Where is the apneustic center located?
Lower pons
What is the apparent function of the apneustic center?
Impulses from the apneustic center have an excitatory effect on the inspiratory area of the medulla.
What happens to a person in whom the apneustic center is damaged?
Abnormal breathing pattern - prolonged inspiratory gasps (apneuses) interrupted by transient expiratory efforts
What part of the brain can override the respiratory center?
Cortex
Which is more difficult, voluntary hyperventilation or voluntary hypoventilation?
Voluntary hypoventilation
What nerves carry output from the respiratory center?
Phrenic nerves (C3-C5) control the diaphragm, other nerves from the spinal column carry signals to the intracostals, abdominals, and accessory muscles such as the SCM
Where are the central chemoreceptors located?
Ventral surface of the medulla
What medium surrounds the central chemoreceptors?
Brain ECF
To what stimulus are the central chemoreceptors responsive?
CO2, indirectly, but no O2. CO2 diffuses across the BBB all the way to CSF, pH in CSF goes down, H+ signal is then seen in the ECF, trigerring the central chemoreceptors.
How quickly do H+ and HCO3- diffuse across the BBB?
Not at all. pH response is modulated by CO2 diffusion only
Which is more pH-responsive to changes in [CO2], blood or CSF?
CSF - does not have nearly the buffering capacity that blood has
