32 Control of Breathing Flashcards
What 3 substances are synergistic in stimulating respiration?
Hypercapnia, hypoxia, acidemia
What substance is most significant in control of respiration?
CO2 (thru central chemoreceptors)
T/F pH, pCO2, PO2 levels physiologically adjust during exercise?
False. They are held constant.
T/F Speech and swallowing present a real problem for respiratory control.
False.They are handled perfectly.
What nerve transmits the Central Pattern Generator’s (CPG) signal?
Spinal motor neurons
Where are the nuclei located of the spinal motor neurons that transmit the CPG signal?
C3-5
-“keeps the diaphragm alive”
At what level is the CPG located?
Medulla
If you lesioned the medulla mid-sagittally, what would happen to breathing?
CPG signal would continue to be generated independently on each side
Pontomedullary transection would do what to breathing?
Nothing
Spinomedullary transection would do what to breathing?
Tongue would keep moving for breath but you would not breathe.
Where is the cell body for External intercostal muscles?
-Thoracic ventral horn (so think if you lesioned all thoracid levels, “chest” inspiration would be difficult, but diaphragm inspiration would continue)
Where is the cell body for diaphragm?
-Ventral horn C3-5
What are the secondary musceles of inspiration?
-Larynx & pharynx (nuc. ambiguus), tongue, sternocleidomastoid, trapezius, nares
Internal intercostals have what function?
Expiration
Where are the nuclei located for secondary muscles of expiration?
- Int. intercostal:thoracic ventral horn
- abdominal: lumbar ventral horn
What is eupnea?
Resting/mild exercising breath pattern
T/F expiratory muscles are active during mild exercise?
False (but yes for intense exercise)
Dorsal Respiratory Group and Ventral Respiratory Group each have what function?
- DRG: Integrates chemoreceptor,stretch, airway, and irritant sensory input (via CN IX & X). Closely associate w/ Nuc. Tractus Solitarius. Has pre-motor & internurons but no motor neurons.
- VRG: the Do-er. Motor nuerons for both inspire and expire. Its sensory info comes from the DRG.
Where is the CPG maybe located?
- Maybe Pre-Botzinger complex (in rostral VRG).
- Or location changes throughout the day.
- Or it is “emergent” from a network.
The pons has what two respiratory neuron groups?
- Apneustic center
- Pneumotaxic center
- (These modulate respiratory activity)
T/F Peripheral chemoreceptors under normal circumstances help keep O2 levels normal.
False. Emergency only.
Where are peripheral chemoreceptors located?
Carotid and aortic bodies.
What 3 things are important to the function of peripheral chemoreceptors?
- Close to lung (rapidly detect changes)
- Highly vascular (similar chemo concentration to systemic blood)
- Both sympa and parasympa input. (therefore autonomic input affects their response)
What are carotid body cells called?
glomus (chemosensitive) cells and sustentacular cells (supportive)
What is the mechanism of peripheral chemoreceptor activation?
- Down O2, or up CO2/acid
- Inhibit K+ channels
- Depolarize
- Ca++ channels open
- Neurotransmitter releases
How do changes in CO2/acid affect glomus cells?
- Mostly make them more sensitive to O2 levels
- Activate them a bit
-T/F CO2 readily crosses the Blood Brain Barrier (BBB) from blood into brain?
True
T/F chemoreceptors respond to CO2 and acid in the same way?
False. It responds less to “other” acids than it does to physiological acidity from CO2.
Active transport of HCO3 from blood into CSF would have what effect on central chemoreceptors?
-They would normalize at a new baseline (occurs in chronic hypercapnia. The kidney also increases serum HCO3 during chronic hypercapnia, reducing drive to breathe and normalizing pH)
What is a medical condition wherin chronic hypercapnia would occur?
COPD
Where are central chemoreceptors located? What is their neurotransmitter?
- Distributed thru medulla. (especially raphe and ventrolateral medulla)
- Serotonin (SIDS cause maybe?)
If central chemoreceptors are in medulla, what are the serotonergic cells in midbrain doing to them??
-Mediating arousal response to CO2
How much of CO2 response is due to central chemoreceptors?
80-90% (the peripheral chemoreceptors are faster to sense/respond to CO2 changes. The “First Line.”)
Pulmonary stretch receptors in muscle layer are fast-adapting or slow?
Slow. (they tell how inflated the lung is)
Pulmonary stretch receptors adjacent to airway epithelium are fast-adapting or slow?
Fast. (the tell us irritants are present) So, smoke a cigarette and you will quickly adapt and not notice how terrible it is.
What do C-fiber receptors in the lung interstitium and alveolar walls do?
- React to chem/mech. stimuli to produce…
- Bronchoconstriction, secretion of mucus, rapid shallow breathing. Stop your inhaled oreo cookie from getting into deeper lung areas.
During wakefulness, (aside from CPG), what provides a tonic drive to breathe?
Reticular activating system
What can the limbic system do to breathing?
Produce sudden sharp inspiration
What are the two kinds of sleep apnea?
- Obstructive (airway dilator activity drops)
- Central (depress response to CO2 & depressed reticular activating system)
What happens to a neuromuscular disease patient who goes to sleep?
Gas exchange worsens. also occurs in lung disease.
What will happen to pleural pressure during obstructive sleep apnea?
Get stronger and stronger
What amount of increase does exercise have on the following things? A)O2 consumption B)cardiac output C)minute ventilation D) oxygen extraction
A)15x
B)5x
C)10x
D)3x
T/F Breathing control is achieved solely by central and peripheral chemoreceptors?
False. Also ergoreceptors, proprioreceptors, collateral input. These provide ANTICIPATORY input.
