What is the function of the Pre-Botzinger Complex?
“Central pattern generator”
Generates the timing (frequency) of the respiratory rhythm
This is the primary source of the respiratory rhythm, but not the only source
Lesion to the Pontine Respiratory Group (PRG) causes what condition?
Apneusis (Inhalation without exhalation)
What are the two big players in determining respiratory frequency?
Pre-Botzinger Complex
Pontine Respiratory Group
What locations in the brainstem are big players in determining respiratory pattern (depth)?
Dorsal Respiratory Group
Ventral Respiratory Group
What nerve is the major synapse target of the Dorsal Respiratory Group?
The phrenic nerve
What is the function of the rostral part of the Ventral Respiratory Group?
Activating the muscles of inspiration - somewhat the diaphragm through the phrenic, but moreso the other muscles of inspiration
What is the function of the caudal portion of the ventral respiratory group?
Activates muscles of expiration
Which of the breathing locations in the brain stem are located in the pons, and which are located in the medulla?
The pontine respiratory group is located in the pons
All others (DRG, VRG, Pre-Botzinger) are located in the medulla
What is the primary function of the pontine respiratory group?
Turning off inspiration
Apneusis comes from pontine damage. What region of the brain would need to be damaged to result in apnea?
Medulla (or the Spinal Cord)
Do chemoreceptors fire faster or slower as a result of increased O2?
Slower
What can the central chemoreceptors respond to?
Why only this?
H+ (from H2CO3 - CO2 in the CSF)
Because CO2 can cross the blood brain barrier.
What neurotransmitter should we associate with the carotid body?
Dopamine
(Don’t worry about why, she just said to associate the two)
Where are the peripheral chemoreceptors located?
In the carotid body and the aortic arch
(The aortic arch is a backup)
What are the peripheral chemoreceptors sensitive to?
CO2 (directly, unlike the central)
O2
H+ (same as central)
What do the slowly adapting stretch receptors respond to?
Tidal volume
When are the slowly adapting pulmonary stretch receptors most useful?
In infants who are just learning to breathe
Adults doing exercise
What is the function of the rapidly adapting pulmonary stretch receptors?
Protect the airways by responding to irritation and eliciting cough.
What nerve do the rapid and slow stretch receptors of the lungs use to communicate to the brain?
Vagus nerve
What is the function of the juxtacapillary (J) receptors?
They are sensitive to pulmonary edema, and cause cough and tachypnea.
What can override the medullary centers?
Cortical influence
Slowly Adapting PSRs
Location
stimulus
effect
role
airways
stretch of lung
inhibit inspir/promote expir.
every breath in infants, exercise/high Vt in adults
Rapidly Adapting PSRs
location
stimulus
effect
role
location: airways
stimulus: irritants
effect: cough to clear airway
role: protective (not every breath)
J receptors
location
stimulus
effect
role
near capillaries in alveoli
pulmonary edema
cough/tachypnea
protective (not every breath)
What two types of stretch receptors override normal control systems and are important for survival?
Rapidly adapting PSR and J receptors
Central chemoreceptors
location
sensitive to
influence
effects
ventral brainstem
pH (direct), CO2 (indirect)
respiratory drive or drive to breath
increase resp. rate/depth in response to hypercapnia
Peripheral chemoreceptors
location
sensitive to
influence
effects
aortic arch and carotid body
O2, CO2, H (directly)
acute changes in blood gases
increase resp. rate/depth in response to hypercapnia, hypoxia or acidosis
central chemoreceptors are sensitive to H ions. does that H cross the BBB or not?
No. That H ion comes from the reaction of CO2 and water with carbonic anhydrase to make H and HCO3
this causes the “drive to breath” to help you breath regularly.
Which nuclei is each respiratory group assx with?
DRG
VRG
PRG
Botzinger
Pre-Botzinger
DRG: NTS
VRG: Nucleus Ambiguus
PRG: parabrachial
Botzinger: retrofacial
Pre-Botzinger: b/t VRG and Botzinger (generates rhythm)
