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14 Cards in this Set
- Front
- Back
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What is a chemoreceptor? What is a respiratory chemoreceptor
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A chemoreceptor is a neuron that alters its discharge rate in response to PO2 or PCO2 changes. A respiratory chemoreceptor is one that alters breathing.
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Where is a major location of O2 and CO2 chemoreceptors in the body?
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The carotid body. ( Rests on Internal carotid)
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What is the innervation scheme of the carotid body?
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Sensory fibers from the petrosal ganglion travel and innervate via the carotid sinus nerve. The superior cervical ganglion also innervates the carotid body by way of the ganglioglomerular nerve. The nodose ganglion is external to the internal carotid artery.
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What are the 2 types of cells in the chemoreceptors in the carotid body?
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chemoreceptor cells
sustentacular cells. |
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How does carotid body activity vary as a function of PaO2
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As PaO2 goes down (move left on his graphy), chemoreceptor activity increases at all levels of CO2, but increases more steeply for highest levels of CO2.
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How does carotid body activity vary as a function of PaCO2?
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As PaCO2 goes up, carotid chemoreceptor activity increases but SLOWLY. Carotid body is more sensitive to hypoxia than hypercapnia.
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What happens if you surgically denervate carotid chemoreceptors in terms of CO2 sensitivity and resting PCO2.
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When the denervation is performed, the sensitivity to CO2 drops sharply at first but then gradually recovers about 75% of the way to normal. PaCO2 obviously increases following denervation, but then decreases to about 1.25 times normal. This shows that there is plasticity.
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What are the roles of carotid bodies?
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1) Major site of O2 chemoreceptors
2) Site of CO2 chemoreception 3) Stabilize breathing to minimize breath to breath variation in PCO2 and PO2 4) Tonic excitatory input to medullary neurons 5) High altitude ventilatory acclimization |
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Where are CO2-H+ receptors located?
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All over the place in the brainstem (along with hypoxic chemoreceptors). It is thought that many of the chemoreceptors may feed into the retrotrapezoidal nucleus. These chemoreceptors have other functions (cardiovascular, metabolic) in addition to breathing.
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If you increase H+ concentration in the ECF by respiratory acidosis (high CO2); in another person if you increase H+ concentration in the ECF by metabolic acidosis (lactic acid), which one will have more phrenic activity?
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Respiratory acidosis. CO2 crosses the intracellular membrane whereas lactic acid does not, suggesting that a change in intracellular CO2 or H+ activates chemoreceptors.
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How does breathing tie in to the anesthetized state?
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Anesthesia is not the same as sleep. Anesthetized individuals can have some apnea. Anesthesia tips the balance towards inhibited breathing state.
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What are respiratory control neurons?
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Rhythm generating neurons
Pattern generating neurons Premotor neurons Motor neurons |
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What are the 3 excitatory inputs into respiratory control neurons
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1)carotid chemoreceptors
2) wakefulness 3) ventrolateral medullary neurons (CO2 H+ chemoreceptors and others) |
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What are some diseases that can occur when the rhythm generator is not functional due to lack of excitatory input.
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Sleep Apnea
SIDS Congenital Central Alveolar Hypoventillation. |
