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34 Cards in this Set

  • Front
  • Back
Peripheral chemoreceptors are sensitive to what chemicals?
Central chemoreceptors are sensitive to what chemicals?
O2, CO2, H+

CO2, but ultimately H+ produced from this CO2
Medullary respiratory center:
Dorsal respiratory group responsible for ______
Ventral respiratory group responsible for ______
Which has periodic firing and responsible for basic ventilation rhythm?
inspiration

expiration

DRG
The DRG responsible for ______ nerve activity has a "ramp-up" response of action potentials
This can be inhibited by impulses from the _______ center
inspiratory

pneumotaxic
Which two nerves terminate near the DRG and VRG and further modulate the output of the inspriatory cells
Vagus and glossopharyngeal nerves (IX and X)
______ center drives the dorsal respiratory group. If you section the spinal cord above this center, what happens?
Apneustic
prolonged inspiration
The _______ center inhibits inspiration by inhibiting the ______ center, or directly inhibiting DRG
Pneumotaxic center
apneustic
Vagus and glossopharygeal have a negative effect on the pneumotaxic and apneustic center, as well as the DRG and VRG
True or False?
False - everything is true except VRG is only inhibited by the cerebral cortex
The major output of the respiratory centers is to what?
Phrenic nerves
CENTRAL CHEMORECEPTORS
Located in the _____ by CN 9/10
Will NOT respond to ______, only responsive to changes in CSF __
medulla
hypoxia
pH (from CO2 crossing blood brain barrier into the CSF, generates H+ ions, decreases pH)
CENTRAL CHEMORECEPTORS:
VSF has a higher/lower buffering capacity than blood.
Compensatory change in ____ occurs as a result of transport across the blood brain barrier.
lower - change in CSF pH for given change in PCO2 is greater than in blood.
Bicarbonate (HCO3)
Arterial ___ is the most important stimulus to ventilation under most conditions and is normally tightly controlled.
The response is magnified if the arterial __ is lowered
PCO2

PO2
PO2 can be reduced to __mmHg before evoking a ventilatory response.
Only the ______ chemoreceptors are involved
50mmHg - this is because of the shape of the dissociation curve - high, flat, doesn't need sensitivity. High sensitivity below 50

peripheral (aortic and carotid bodies)
Peripheral chemoreceptors are not very sensitive to significant drops in ___, but combined with ___ increase you get an amplication of the response
PO2

PCO2
In humans, the _____ but not the ____ bodies respond to a fall in arterial pH.
carotid (increases in chemoreceptor activity in response o decrease in arterial PO2 are potentiated but decreases in pH)

aortic
The response of the peripheral chemoreceptors to arterial PCO2 is more/less important than that of central chemoreceptors.
It is also faster/slower.
less important (only 20% of ventilatory response attributed to peripheral)
BUT
Faster response, good for abrupt changes in PCO2
Peripheral chemoreceptors respond to ____ levels due to high blood flow and small a-v difference
arterial
LUNG RECEPTORS
Within airway smooth muscle
Impulses travel in the vagus
Slow respiratory frequency
Pulmonary stretch receptor
Hering-Bruer reflexes have what main function?
Self-regulatory mechanism or negative feedback (more important in newborns)
LUNG RECEPTORS
Between airway epithelial cells
Stimulated by noxious gases and dust
Impulses travel up Vagus
Reflex includes bronchoconstriction and hyperpnea
Irritant Receptors
might have something to do with asthma
LUNG RECEPTORS
Located in the alveolar wall close to capillaries
Stimulated by injected chemicals in pulmonary circulation or engorgement of pulmonary capillaries
Impulses travel up the vagus
Result in rapid shallow breathing and shortness of breath (apnea)
J receptors for "juxta-capillary"
LUNG RECEPTORS
Associated with bronchial circulation rather than pulmonary.
Respond quickly to chemicals injected into bronchial circulation
Reflex is rapid shallow breathing, bronchoconstriction, mucous secretion
Bronchial c-fibers
NON LUNG RECEPTORS
Extension of irritant receptors
Reflex cough, sneeze, bronchoconstriction, laryngeal spasm (with endotracheal tube)
Nose and upper airway receptors
NON LUNG RECEPTORS
Impulses from moving ____ are part of the stimulus to ventilation during early exercise
limbs
Joint and muscle receptors
NON LUNG RECEPTORS
Many muscles contain spindles that sense the elongation of the muscle. Reflexly control strength of receptor.
Gamma system
NON LUNG RECEPTORS
Increase in arterial blood pressure can cause reflex hypoventilation thorugh stimulation of what baroreceptors?
Decrease in blood pressure may result in what?
aortic and carotid

hyperventilation
Pain often caues a period of apnea followed by ____ventilation
Heating of the skin may result in ________
hyperventilation

hyperventilation
Concerning the respiratory centers:
A.The normal rhythmic pattern of breathing originates from neurons in the motor area of the cortex.
B.Inspiratory activity originates in the ventral respiratory group of cells in the medulla.
C. Impulses from the pneumotaxic center can stimulate inspiratory activity.
D.The cortex of the brain can override the function of the respiratory centers.
E.The only output from the respiratory centers is via the phrenic nerves.
Answer D Personal experience indicates that cortical control, for at least short periods of time, is possible.
Answer A. No! The rhythmic pattern of breathing originates in the brainstem, removal of cortical input to the brainstem dose not stop breathing.
Answer B. No! its the dorsal respiratory group.
Answer C. No! The pneumotaxic center is a inhibitory group of neurons.
Answer E. No! Additional output from the respiratory center travels to the internall and external intercostals.
Concerning the central chemoreceptors:
A.They are located near the dorsal surface of the medulla.
B.They respond to both the PCO2 and the PO2 of the blood.
C.They are activated by changes in the pH of the surrounding extracellular fluid.
D.For a given rise in PCO2 the pH of cerebrospinal fluid falls less than that of blood.
E.The bicarbonate concentration of the CSF cannot affect their output.
Answer: C.—the reaction of CO2 and water produces carbonic acid which dissociates to bicarbonate ion and hydrogen ion. The H+ directly stimulates respirations.
Answer A: No! It is the ventral surface.
Answer B. No! The central chemoreceptors do not respond to changes in PO2
Answer D: No!—the CSF has a lower buffering capacity when compared to blood.
Answer E: I do not understand this answer ??? LEW.
Concerning the peripheral chemoreceptors:
A.They respond to changes in arterial PO2, but not pH.
B.Under normoxic conditions the response to changes in PO2 is very small.
C.The response to changes in PCO2 is slower than for central chemoreceptors.
D.They are the most important receptors causing an increased ventilation in response to a rise in PCO2.
E.They have a low blood flow per gram of tissue.
Answer: B the inspired O2 must decrease to near ½ to elicit an increase in ventilation.
Answer A: No! —they also respond to pH.
Answer C: No!—the magnitude of the CO2 response in the peripheral chemoreceptors is small when compared to the central receptor but it is faster.
Answer D. No!. The PCO2 response shows a greater sensitivity in the central chemoreceptors.
Answer E: No! Thsi tissue has the highest
Concerning the ventilatory response to carbon dioxide:
A. It is increased if the alveolar PO2 is raised.
B. It depends only on central chemoreceptors.
C. It is increased during sleep.
D. It is increased if the work of breathing is raised.
E. It is a major factor controlling the normal level of ventilation.
Answer: E
Answer A. No!. If PAO2 increases given the physics and the alveolar gas equation, PACO2 must go down, therefore the PCO2 stimulus is decreased.
Answers B, No! Peripheral chemo receptors respond to carbon dioxide.
Answer C. No! It is reduced during sleep.
Answer D. No! Actually there is a decrease in carbon dioxide sensitivity
Concerning the ventilatory response to hypoxia:
A. It is the major stimulus to ventilation at high altitude.
B. It is primarily brought about by the central chemoreceptory.
C. It is reduced if the PCO2 is also raised.
D. It rarely stimulates ventilation in patients with severe chronic lung disease.
E. It is important in mild carbon monoxide poisoning.
Answer: A. The hyperventilation removes all carbon dioxide drive..
Answer B: Central chemoreceptors are not sensitive to oxygen. .
Answer C: No! .As the carbon dioxide levels go up the oxygen lack becomes the primary drive.
Answer D: No! It is a very important stimuli under these circumstances. Note: the PCO2 is high and their receptors do not function to stimulate respiration, leaving the hypoxic receptors driving respiration.
Answer E: No! In mild CO poisoning, the PO2 will be normal and therefore not altering respirations.
The most important stimulus controlling the level of resting ventilation is:
A.PO2 on peripheral chemoreceptors.
B.PCO2 on peripheral chemoreceptors.
C.pH on peripheral chemoreceptors.
D.pH of CSF on central chemoreceptors.
E.PO2 on central chemoreceptors.
Answer: D is true—central chemoreceptors are the most sensitive controllers of ventilation through CSF pH..

Answer A: Peripheral chemoreceptors poorly sensitive to PO2.
Answer B: Peripheral chemoreceptors poorly sensitive to PCO2.
Answer C: Peripheral chemoreceptors poorly sensitive to pH.
Answer E: Central chemoreceptors not sensitive to PO2.
Exercise is one of the most powerful stimulators of ventilation. It primarily works by way of:
A. Low arterial PO2.
B. High arterial PCO2.
C. Low PO2 in mixed venous blood.
D. Low arterial pH.
E. None of the above.
Answer: E. Answers A, B, C, and D have not been shown to stimulate ventilation on exercise, at least at moderate levels. One possible mechanism is that joint and muscle activity have been shown to initiates increased ventilation.
Concerning Hering-Breur inflation reflex:
A.The impulses travel to the brain via the carotid sinus nerve.
B.It results in further inspiratory efforts if the lung is maintained inflated.
C.It is only seen in adults at small tidal volumes.
D.It may help to inflate the newborn lung.
E.Abolishing the reflex in many animals causes rapid shallow breathing.
Answer: D Could be involved in the limitations of the first breath.
Answer A. No! It is via the vagus nerve.
Answer B. No! Observation
Answer C. No! Observation
Answer E. No! Causes slow – deep breathing