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23 Cards in this Set

  • Front
  • Back
Define a respiratory chemoreceptor:
A neuron whose discharge rate is altered by changes in the PO2 or PCO2 in the surrounding environment and in turn alters breathing.
2 major sites of chemoreceptors:
-Carotid body
What type of chemoreceptors are in the carotid body?
O2 and CO2
What is the carotid body innervated by (2 things)
1. Sensory fibers originating in Petrosal Ganglion & traveling thru the Carotid Sinus nerve.
2. Superior cervical ganglion
What do carotid body cell clusters consist of?
-Chemoreceptor cells
-Sustentacular cells
What are carotid body chemoreceptors more sensitive to; O2 or CO2 changes?
When are carotid body nerve afferents most active?
When Po2 goes below 50
How does denervating the carotid chemoreceptors of goats affect arterial PCO2 and CO2 sensitivity?
Just after surgery, their resting arterial CO2 levels go up and ventilation of CO2 falls - they hypoventilate.
How do the goats change 10 days after denervation?
They recover function - breathing and CO2 sensitivity return to normal.
So what does that tell us about the carotid chemoreceptors?
They are important in not only sensing O2 but also CO2 levels.
What is the resting activity of the carotid chemoreceptors?
They give tonic excitatory input to the medullary neurons.
What is the important function of carotid chemoreceptors?
Stabilization of breathing to minimize breath-to-breath variations in PCO2 and PO2.
What happens to the carotid chemoreceptors at high altitudes?
Ventilatory acclimatization
Where are the chemoreceptors in the BRAINSTEM?
In the ventral medulla and pons
What are the medullary and brainstem chemoreceptors sensitive to?
CO2 and H+
Are the chemoreceptor functions in the pons/medulla restricted to just regulating breathing?
No; also CV, metabolic, temp, and arousal regulation.
What happens as the acid concentration in the medulla increases?
Phrenic nerve activity increases and respiration increases.
What will elicit a greater response in ventilations; a metabolic acidosis or respiratory?
Respiratory - the chemoreceptors in the medulla respond more to hypercapnia than acid.
How many major excitatory inputs are there for respiratory control neurons?
At least 3
What are the 3 major excitatory inputs are there for respiratory control neurons?
1. Carotid chemoreceptors
2. Wakefulness
3. Ventrolateral Medullary Neurons
What are the 2 subtypes of VLMNs that give excitatory input to the respiratory control neurons?
-CO2 and H+ chemoreceptors
-Chemoreceptor-independent neurons
What do these 3 major inputs excite?
The respiratory controller
What does the Respiratory Controller control?
1. Rhythm generator
2. Pattern generator
3. Pre-motor neurons
4. Motor neurons