Flashcards in Ctrl of Breathing Deck (16)
How does the pneumotaxic center contribute to respiration?
regulates respiratory rate
How does the apneustic center contribute to respiration?
Where are the pneumotaxic and apneustic center located?
When the medulla triggers rhythm generating neurons, (inspiration/expiration) occurs; when the signal stops, (inspiration/expiration) occurs.
(these signals trigger motor nerves that activate muscles involved in respiration)
Where are gamma efferents located?
How do baroreceptors affect respiration?
signal to medulla to increase respiration when decreased BP sensed
Alveolar ventilation is regulated in response to:
arterial PCO2, pH and PO2
What is sensed to regulate minute to minute stability of arterial gases and pH?
partial pressure of arterial CO2
(metabolism relative to ventilation)
How do high CO2 levels in the blood affect ventilation?
--In the extracellular fluid, CO2 forms bicarb and H ions, which are sensed by H sensitive neurons.
--Medulla senses pH changes
--Respiration is increased in response
CO2 freely diffuses across BBB?
How do chemosensitive cells react to long term elevations in PCO2?
reset themselves to the new nml:
--bicarb is pumped into BBB via transport protein
--medulla senses the increased pH and lowers respiratory drive
If the respiratory drive is too high (COPD) in response to chronically elevated PCO2, you will see metabolic (acidosis/alkalosis) in response to respiratory (acidosis/alkalosis)
**the medulla is sensing decreased pH, which increases respiratory rate; high bicarb crosses BBB to reset ventilation to function at a higher CO2 level
What type of channels are present in carotid bodies? How do they work?
O2 sensitive K channel
--decreased O2 inhibits the channel
--this depolarizes the cell and increases excitability
--excitatory neurotransmitters are released to the glossopharyngeal nerve
What is sensed by the carotid bodies?
arterial PO2 (not content)
Carotid bodies are (fast/slow) responders to gas changes
How are central chemoreceptors reset at high altitude (chronic hypoxia)?
--arterial PO2 decreased due to altitude = carotid body increases alveolar flow (ventilation)
--this decreases arterial PCO2 which raises pH in brain
--central chemoreceptors block increased respiratory drive
--bicarb moves out, which lowers/resets the pH