Lecture 23 Flashcards
Final exam content
A loud cough is the equivalent of_______
moving about 2L of air into and out of the lungs quickly
Where are the primary locations of the peripheral chemoreceptors?
- carotid body
- aortic body
What chemicals do the chemoreceptors respond to in order of greatest response to least?
- pH/ H+ concentration
- pCO2
- arterial pO2
What is the major trigger the chemoreceptors in the brainstem respond to?
H+ concentration in the CSF
Chemoreceptors don’t usually respond to hypoxia until about_______.
a PO2 of 70mmHg
A alpha neurons are_____
These respond by______
fast motor neurons
increasing tidal volume
List the muscles of breathing…
diaphragm, external intercostals, internal intercostals, and accessory muscles (sternocleidomastoid, scalene, pectoris minor, and abdominal muscles).
Where are the DRG and VRG nuclei live?
In the lower medulla in the reticular formation
The left side of the brainstem controls the______ respiratory muscles.
contralateral (right side/opposite side)
Where is does the crossover happen for the motor neurons coming from the brainstem?
crossover happens at the decussation of the pyramids
What is reciprocal inhibition?
When the expiratory center is activated it can cross talk with the inspiratory center and inhibit it
Where is the DRG located specifically within the reticular formation of the medulla?
The nucleus tractus solitarius (NTS)
What is the DRG and what feeds into it?
A control center and processor for regulating inspiration.
the pH, CO2 and O2 chemoreceptor sensors via CN IX and X. Also input from the baroreceptors.
What muscles does the DRG control?
diaphragm via the phrenic nerve, accessory muscles (abdominal muscles and internal intercostal muscles)
What is the main function of the DRG?
Controls inspiratory rate via control over the inspiratory and forced expiratory muscles
How does the Botzinger complex (located in the VRG) influence the DRG?
It is the site of respiratory rhythmogenesis that has reciprocal innervation with the DRG and controls the spacing between breaths (pace of inspiration)
What are the two main functions of the VRG and what muscles does it innervate?
Keeps the upper airways open via the skeletal muscles around the larynx (pharyngeal constrictor muscles)
respiratory rhythmogenesis via the Botzinger complex.
What does the pontine respiratory group (PNG) do? What sensors feed into the PNG?
stretch receptors and irritant receptors feed into the PNG.
It passes info to the DRG and is able to manipulate the length of time spent in inspiration.
What type of breathing happens when the pathway between the PNG and DRG is lesioned?
Apneustic breathing (long inspiration followed by a quick expiration– BAD!)
Why is there a delay in the response from increased nonvolatile acids by the brainstem when compared to an increase in CO2?
H+ are charged and cannot cross the BBB without a protein carrier whereas CO2 can cross the BBB readily and response by the brainstem to CO2 is instantaneous
What is the pH of the CSF? Why does this differ from normal blood pH?
CSF pH: 7.32
The CSF has its own blood buffering system
What is the pCO2 of the CSF?
pCO2 of arterial blood?
CSF PCO2: 50mmHg
arterial blood PCO2: 40mmHg
What is the primary chemical that sets off the chemoreceptors in the brainstem?
H+ (pH)
increased CO2 ______ brain blood flow
increased
Vasodilation occurs in response to elevated CO2
