Respiratory 5 Flashcards
The ultimate goal of respiration is to maintain proper concentrations of what 3 things in the tissues?
O2, CO2 and H+
Excess CO2 or H+activates respiratory centers to _____ alveolar ventilation.
increase
Decreased O2 ____ alveolar ventilation
increases
Decreased O2 increases alveolar ventilation. However, it does not directly impact central respiratory centers but instead acts on ______ that relay the signal to the central respiratory center.
peripheral chemoreceptors
Involves descending input from the thalamus and cerebral cortex, can bypass the respiratory control centers in pons & medulla–Activated during talking, sneezing, singing, swallowing, coughing, defecation, anxiety, fear, etc.
Corticospinal tract
Primarily controlled by changes in PCO2•Less sensitive to PO2 and H+•Pulmonary mechanical receptors–Activated by Respiratory Centers in the pons & medulla (ex. DRG and VRG)
Ventrolateral tract–
What are the 2 Medullary Respiratory Centers:
–Dorsal Respiratory Group (DRG)
–Ventral Respiratory Group (VRG)
What are the 2 Pontine Respiratory Groups
–Pneumotaxic Center
–Apneustic Center
–Inspiratory Center
–Receives afferent input from Cranial Nerves IX (chemoreceptor) and X (chemoreceptor & mechanoreceptor)
–Provides excitatory inspiratory stimuli to phrenic motor neurons
–Sets the basic rhythm for breathing by setting the frequency of inspiration
Dorsal Respiratory Group: DRG
What 2 CN give afferents to DRG?
CN IX and X
Mostly involved in expiration–Primarily responsible for expiration•Expiration is normally a passive process, so these neurons are quiescent during normal breathing•Activated when forceful expiration is required
Ventral Respiratory Group: VRG
_____ is normally a passive process, so these neurons are quiescent during normal breathing
Expiration
The ________ are the only Receptors Sensitive to O2
Peripheral Chemoreceptors
The Peripheral Chemoreceptors are stimulated by what things?
Decrease O2
INcrease in CO2
INcrease in H+
What does O2 must fall to to cause a response by peripheral chemoreceptors?
60 mmHg
The central chemoreceptors are stimulated by what?
Increase in H+ when CO2 is increased
Afferent (sensory) information regulates the activity of the _________ via central and peripheral chemoreceptors and also mechanoreceptors
medullary inspiratory center (DRG)
MOST important for minute-to-minute control of breathing•Located on ventral surface of medulla•Activation stimulates the DRG• are VERY sensitive to changes in pH of CSF
Central Chemoreceptors
Activation of central chemoreceptors stimulate the _____
DRG
Central Chemoreceptors are VERY sensitive to changes in ___ or _____
pH of CSF
If AV increases, DRG recruits _____
VRG
What causes DRG to recruit VRG?
AV increases
Chemoreceptors in the CSF are only sensitive to changes in ____ concentration.
H+
INcrease in H+ leads to ___ in AV
INcrease
When CSF [H+] _______, there is an increase in respiratory volume and rate
increases
_____ is permeable to the Blood Brain Barrier
CO2
In the CSF, CO2 is converted to H+ and HCO3- via ______
Carbonic Anhydrase
The H+ produced in the CSF activates the ______ which stimulates the DRG
Central Chemoreceptors
The effect of a change in CO2 is _____ acutely
potent
The effect of a change in CO2 is _____ chronically
diminished
Central Chemoreceptors are most effective within _____ days after a change in central CO2.
1-2 days
Why are central chemoreceptors most effective within 1-2 days after a change in central CO2?
–the kidneys will have begun to compensate, reabsorbing HCO3-
–HCO3- has slowly diffused through the BBB and CSF barriers to buffer H+
A danger for patients with chronic respiratory problems is that the kidney and buffer mechanisms compensate for the elevated PaCO2 (and H+) so that they no longer stimulate the medullary respiratory centers. Then the ______ -the only receptors that sample oxygen content—become critical for respiratory control.
peripheral chemoreceptors
What 2 CN are associated with peripheral chemoreceptors?
CN IX and X
where are the receptors for peripheral chemoreceptors located?
Carotid and aortic bodies
______ are sensitive to low PaO2, high CO2, and low pH; larger response if both O2 is low and CO2 is high
Peripheral chemoreceptors
What are the 3 conditions that peripheral chemoreceptors are sensitive to?
Low PaO2, High PaCO2, and Low pH
What are the only receptors sensitive to O2 concentrations in the brainstem?
Peripheral chemoreceptors
At PaO2 < _____mmHg, there is a LARGE increase in alveolar ventilation due to the ____ chemoreceptors?
60 mmHg; peripheral chemorectors
Increases in PaCO2 increase the rate of firing of _____ to increase respiration
both aortic and carotid bodies
Decreases in arterial pH increase the rate of _____
carotid bodies
Hypoxemia enhances the response to _______
PaCO2.
Are central or peripheral responses to changes in PaCO2 stronger?
Central
Which chemoreceptors respond more quickly to changes in PaCO2?
Peripheral
If PaCO2, does alveolar ventilation increase or decrease?
Increase
Does sleep increase or decrease CO2?AV?
Increases both
Do opioids increase or decrease CO2?AV?
Increase both
Does DKA increase or decrease CO2?AV?
Decrease both
Does DKA show an enhanced or decreased response to PaCO2?
Enhanced response
Does sleep and opioids show an enhanced or decreased response to PaCO2?
Decreased response
Most inhaled anesthetics cause respiratory depression by inhibiting the DRG and abolish/attenuate the response to ____ and _____
hypoxemia (decreased O2) and hypercarbia (increase CO2)
Nitrous oxide actually _______ respiratory rate (tachypnea) and ________ tidal volume (via central stimulation) so there is minimal change in minute ventilation and PaCO2 levels.
increases respiratory rate (tachypnea) and decreases tidal volume (via central stimulation)
Does nitrous oxide cause a large or small change in minute ventilation and PaCO2 levels?
Small change
Hypoxic drive is ______ by nitrous oxide
decreased
Nitrous oxide ______ pulmonary vascular resistance
increases
