respiratory control Flashcards
5 main respiratory centers in the brainstem
Dorsal respiratory group (DRG)
Ventral respiratory group (VRG)
Pontine respiratory group (PRG)
Botzinger complex (BotC)
Pre-Botzinger complex (Pre-BotC)
Which respiratory centers are supposed to generate the timing (frequency) of respiratory rhythm?
Pre-Botzinger complex
PRG
How was the PRG found to be associated w/ timing or frequency?
A lesion in the PRG caused apneusis (stuck in inspiration)
Transition from inspiration to expiration and vice versa is needed for rate/rhythm
SO, the PRG must play a role
SO, the function of the PRG is what?
Turn off inspiration
Function of DRG
Mostly pre-motor to phrenic nerve innervation
Lots of sensory information
Function of VRG
Rostral - pre-motor to phrenic and other inspiration muscles
Caudal - pre-motor to upper airway and other expiration muscles
SO, DRG and VRG control the what?
The depth (tidal volume) of breathing
Apneusis vs. apnea
Damage that could cause each
Apneusis - maintained inspiration (no expiration) - Pons damage
Apnea - no respiratory effort - medullary/spinal damage
Explain this equation:
VE = f x VT
f = timing/frequency of breaths
VT = tidal volume
VE =
Explain the cycle of respiratory control (4 parts)
Medullary centers affect respiratory muscles (respiration), which then affect chemical balances (CO2, O2, pH), which affect chemoreceptors, which stimulate the medullary centers
3 main chemoreceptor types (chemicals they respond to) in respiratory system
Increased or decreased causes receptor firing (for each)?
inc CO2 - increased
dec O2 - increased firing
increased H+ - increased
Why are chemoreceptors so important? (What would happen w/o them?)
Normally, neurons would slow down w/ less O2 to not use up ATP for APs
BUT, this would cause decreased ventilation and further hypoxia
SO, the chemoreceptors cause INCREASED neuron activity when the system would otherwise want to slow down
2 sets of chemoreceptors (w/ locations)
Central - brain
Peripheral - carotid (uses dopamine) and aorta
Activation of central chemoreceptors
Specific location?
CO2 crosses BBB, reacts w/ water and is converted to HCO3 and H+, so the increased H+ triggers the chemoreceptors to increase breathing (“respiratory drive”)
Ventral medulla
Peripheral chemoreceptor activation
Ultimate effect?
Direct activation by changes in O2, CO2, and/or H+ (pH)
Increased firing rate of afferents to brainstem
Increased frequency and tidal volume (controlled by centers in brainstem)
Slowly-adapting mechanoreceptors in the lungs
Function?
Location?
Slow pulmonary stretch receptors - sensitive to airway stretch (i.e. lung volume increase)
Causes fibers in vagus n. firing to inhibit/terminate inspiration and prolong expiration
Located in airways
So, explain the 4 parts of the respiratory control cycle
Medullary centers affect respiratory muscles (breathing), which changes lung volume, thus affecting pulmonary stretch receptors, which act on medullary centers
When are pulmonary stretch receptors most important? (2)
Infants
Adults during exercise
Rapidly-adapting mechanoreceptors in the lungs
Function?
Location?
Rapid stretch receptors
Irritation, foreign bodies, stretch cause vagus nerve fibers to innervate brain, causing COUGH
Located in airways
J receptors
Effect?
Receptors near alveolar blood vessels that are sensitive to pulmonary edema
Again, vagus n. fibers
Cause cough, tachypnea
When are J receptors and rapid-adapting receptors used?
ONLY when in need of immediate protection
Explain cortical influences on breathing
When talking or holding your breath, the cortex bypasses the medullary centers and sends direct input to respiratory muscles
AGAIN, only when needed
