RESP 5 Flashcards
The ultimate goal of respiration is to maintain proper concentrations of __________________ in the tissues.
O2
CO2
H+
Excess CO2 or H+ activates respiratory centers to _________ alveolar ventilation.
increase
Decreased O2 _________ alveolar ventilation.
increases
What is detected by peripheral and central chemoreceptors?
high CO2
high H+
What is detected by peripheral chemoreceptors?
low O2
What are the two basic controls of breathing?
voluntary (corticospinal tract)
automatic (ventrolateral tract)
What does the voluntary/corticospinal tract involve?
descending input from the thalamus and cerebral cortex, can bypass the respiratory control centers in pons & medulla
When is the voluntary/corticospinal tract active?
talking, sneezing, singing, swallowing, coughing, defecation, anxiety, fear
What is the automatic/ventrolateral tract controlled by?
– Primarily controlled by changes in PCO2
* Less sensitive to PO2 and H+
* Pulmonary mechanical receptors
When is the automatic/ventrolateral tract activated?
Respiratory Centers in the pons & medulla (ex. DRG and VRG)
What are the two areas of the brainstem that control respiration?
medullary respiratory center
pontine respiratoyr group
What are the two sections of the medullary respiratory center?
– Dorsal Respiratory Group (DRG; inspiration)
– Ventral Respiratory Group (VRG; active expiration and inspiration)
What are the two sections of the pontine respiratory group?
– Pneumotaxic Center
– Apneustic Center
What is the dorsal respiratory group (DRG)?
- nucleus of the tractus solitarius
- inspiratory center
- one of the medullary respiration centers
What does the DRG receive afferent input from?
CN IX (chemoreceptor)
CN X (chemoreceptor and mechanoreceptor)
What does the DRG mirror the activity of?
the diaphragm
How does the DRG provide excitatory inspiratory stimuli to phrenic motor neurons?
- Sets the basic rhythm for breathing by setting the frequency of inspiration—Central Pattern Generator
- Signal begins weakly, increases steadily for 2 seconds, then will abruptly cease for ~3 seconds before resuming the cycle (12-20 breaths per minute
DRG contains opiate receptors (u receptors) that, when activated,
______ respiration
inhibit
Which medullary respiratory center is mostly involved in expiration?
VRG
VRG is the control for the motor neurons in the…
- Expiratory muscles (abdominals, internal intercostals)
- Accessory inspiratory muscles
What is the pneumotaxic center?
- When activated, shortens the time of inspiration (possibly by inhibiting the Apneustic Center).
- Might inhibit the Apneustic Center.
- decrease tital volume
What is the apneustic center?
- Its activation causes excitation of
the DRG which results in prolonged
inspiration with brief periods of
expiration. - Antagonist to Pneumotaxic Center
- increase tital volume
What is the Hering-Breuer Reflex?
Stretch receptors in bronchi and bronchioles are activated when the lungs over-stretch
How do you activate the Hering-Breuer reflex?
Stops further inspiration and decreases rate.
What stimulates an irritant receptor?
noxious exogenous substances, endogenous agents, and mechanical stimulation
What does the irritant receptor cause?
Promotes rapid, shallow breathing, coughing, sneezing
Where are irritant receptors located?
between epithelial cells in conducting zone
What do activation of J receptors do?
rapid, shallow breathing and a sensation of dyspnea
What are the J receptors stimulated by?
In alveolar walls, “Juxtacapillary” and stimulated by alveolar inflammatory processes (pneumonia), pulmonary vascular congestion (congestive heart failure), and edema.
What do joint and muscle proprioceptors do to DRG?
increase activity of DRG to increase rate of breathing
Joint & Muscle Proprioceptors are sensitive to change in…
position and muscle movements - not metabolism
Central Chemoreceptors are most effective within ___________ after a change in central CO2
1-2 days
Where are peripheral chemoreceptors located?
aortic bodies = vagus
carotid bodies = glossopharyngeal
Where are central receptors?
Located on ventral surface of medulla
What are peripheral chemoreceptors sensitive to?
- Sensitive to (activated by) Low
PaO2, High PaCO2, and Low pH
– Only sensitive to dissolved gases
What are central chemoreceptors sensitive to?
changes in pH in the CSF
What leads to an enhanced response to PaCO2?
metabolic acidosis
What leads to a depressed response to PaCO2?
sleep
opoids
narcotics
chronic obstruction
deep anesthesia
Most inhaled anesthetics cause respiratory __________.
depression
What anesthetic does not cause a respiratory depression?
nitrous oxide
Hypoxic drive is _________ by nitrous oxide
decreased
