Respiratory Week 2 Flashcards
The burst duration of the phrenic nerve firing controls what aspect of quiet breathing?
Depth
The inter-burst interval of the phrenic nerve firing controls what aspect of quiet breathing?
Rate
For normal, quiet inspiration the phrenic nerve and the __________ motor neurons are simultaneously active
External intercostal motor neurons
Where are the cell bodies of the expiratory motor neurons located?
In the ventral horn of the spinal cord (some thoracic, some lumbar)
What part of the brainstem contains a respiratory neural network that is essential and sufficient for producing motor drive to respiratory muscles?
The medulla
What does the dorsal respiratory group (DRG) control?
Inspiratory center. It contains the nucleus of the solitary tract (NTS) and is responsible for the autonomic rhythm of respiration.
Connects to the phrenic nerve which then innervates the diaphragm to control breathing
What does the ventral respiratory group (VRG) control?
Expiratory center. About 2/3 inspiratory neurons, about 1/3 expiratory neurons. Contains the pre-Botzinger complex
Mostly rhythm/pattern generator.
Mediates expiration under non-rest conditions; otherwise quiet
What are the pontine respiratory centers?
The pontine respiratory group (PRG) and the apneustic center
What does the pontine respiratory groups (PRG) control?
Electrical stimulation in late inspiration that facilitates the termination of inspiration (not imp. for normal breathing but can influence it)
** can inhibit the apneustic center
What does the apneustic center control?
Produces tonic contraction of the diaphragm (keeps the “on” switch for the inspiratory center)
Where do afferent lung receptor inputs terminate?
In the NTS of the DRG
Three types of afferent lung receptor inputs?
- Lung stretch receptors
- Rapidly adapting receptors
- Lung C fibers (pulmonary c-fibers/J-receptors) & bronchial c-fibers
What do slowly adapting pulmonary stretch receptors do? Where are they located?
Located in the smooth muscle of the airways
Responsible for the Hering-Breuer Inflation Reflex: terminates inspiration, prolongs expiration. Important at large tidal volumes (>800ml) in adults or just normal breathing in babies
Generally insensitive to chemicals EXCEPT increasing airway CO2 will decrease their activity
What are Rapidly Adapting Receptors? Where are they located?
Located in the airway epithelium and smooth muscle
Sensitive to chemical irritants (particularly histamine). Reflex responses: cough, sneeze, bronchoconstriction, hypernea
Neural discharge of the slowly adapting pulmonary receptors is dependent on lung inflation or deflation?
Inflation
Increases with inflation, decreases with deflation
Continuous discharge with sustained inflation
Neural discharge of rapidly adapting receptors is dependent on lung inflation or deflation?
Either
Unclear whether they function during normal breathing
What are vagal lung c-fibers? Two types?
Unmyelinated, slowly-conducting fibers. Primarily chemosensitive
Two types: pulmonary and bronchial
Where are pulmonary c-fibers/j-receptors? Function?
Accessible through pulmonary circulation
Respond strongly to histamine, prostaglandins and pulmonary congestion
Cause rapid, shallow breathing or sometimes apnea
When are pulmonary c-fibers/j-receptors active?
In pulmonary edema
When are bronchial c-fibers active?
During asthma or allergic reaction
What are bronchial c-fibers? Where are they located?
Accessible through bronchial circulation
Respond strongly to histamine and prostaglandins
Stimulation causes rapid, shallow breathing, apnea, increased mucous secretion, bronchoconstriction + sometimes cough
What links metabolism to ventilation?
Central and peripheral chemoreceptors
Where are peripheral chemoreceptors located?
Carotid bodies and aortic arch
Peripheral chemoreceptors located in carotid bodies have afferent neurons connecting them to what cranial nerve?
Glossopharyngeal (IX)