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18 Cards in this Set
- Front
- Back
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Breathing is involuntary and controlled by the __________ and _________.
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Medulla and pons
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The inspiratory center is located in the _____ group of neurons.
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Dorsal respiratory group of neurons
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What is the role of the dorsal respiratory group of neurons?
What input do they receive and via which nerves? What output does it provide? Via what nerve? |
Dorsal resp group = inspiratory center; establish basic rhythm for breathing by setting frequency of inspiration.
Received input from peripheral chemoreceptors via glossopharyngeal (CN IX), and vagus (CN X). Motor output via phrenic nerve. |
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The _____ nerve provides motor output responsible for breathing at spinal roots C________.
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Phrenic nerve at roots C3, C4, C5
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What role do vagal efferents play in respiration?
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Vagal efferent release Ach to induce bronchoconstriction and increased mucosal secretions.
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The expiratory center is located in the ______ group of neurons.
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Ventral respiratory group of neurons
Remember: expiration is normally passive; these neurons are inactive during quiet breathing |
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Central chemoreceptors:
Location Stimuli Effect |
Located in brain stem
Respond to changes in pH of CSF; decreases in pH result in hyperventilation Goal is to keep arterial PCO2 within normal range. |
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Afferent vs Efferent (general)
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Afferent: Sensory
Efferent: Motor (exit) |
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List the feedback loop for changes in PCO2 at the level of the central chemoreceptor. Begin with an increase in arterial PCO2.
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Inc'd arterial PCO2-->Inc'd CSF PCO2-->Dec'd CSF pH-->Stimulation of central chemoreceptor-->Stimulation of Medullary resp center-->inc'd ventilation-->dec'd PaCO2
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Peripheral Chemoreceptors:
Location Stimuli Afferent Nerves |
-Located in carotid and aortic bodies (carotid bodies more impt)
-Glossopharyngeal for carotid info, vagus for aortic bodies info Respond to: -Decrease in PaO2 (most impt responsibility), but only responds when PO2 decreases to less than 60mmHg!! -Inc in arterial PCO2 (less impt effect) -Decrease in arterial pH--can detect H+ changes! |
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When is peripheral chemoreceptor response to PCO2 augmented?
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During times of arterial hypoxemia
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Why does chronic hypercapnia blunt the ventilatory response?
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With chronic hypercapnia, kidneys begin to compensate for dec'd pH by excreting less bicarb (compensatory metabolic alkalosis), thus, respiratory response is blunted
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When is ventilatory response to CO2 changes decreased?
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With sleep and narcotics
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What is the Hering-Breuer reflex?
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Inspiratory inhibition with sustained lung inflation (to prevent over-inflation); mediated by stretch receptors
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Function of muscle spindles in the chest wall.
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Adjust output of resp muscles if desired degree of muscular work hasn't been achieved.
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Ipratropium:
Drug class Effects |
-tropium; tiotropium
Blocks muscarinic cholinergic receptors and results in bronchodilation and dec'd mucous production |
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beta-2 receptors:
Location of highest density EFfect |
Most dense in peripheral airways (smaller airways)
Result in dilation |
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alpha-adrenergic receptors:
Effect on respiratory system |
Bronchoconstriction
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