Control of Respiration Flashcards
What are the 3 parts involved in the control of respiration?
Central Controller
Sensors
Effectors
Where is the central controller of respiration located?
In the brainstem in the medulla and pons
What are the parts of the medullary respiratory center?
Dorsal Respiratory Group
Ventral Respiratory Group
What is the role of the medullary respiratory group?
Generates the breathing pattern
What is the role of the Dorsal Respiratory Group?
Inspiration
What is the role of the Ventral Respiratory Group?
Expiration
What are the parts of the pontine respiratory group?
Apneusitic Center
Pneumotaxic Center
What is the role of the pontine respiratory group?
Controls the breathing pattern
What is the role of the Apneusitic Center?
Excitatory effect on the DRG (increases inspiration)
What is the role of the
Pneumotaxic Center?
Inhibitory effect on the DRG (decreases inspiration)
What is the role of the central chemoreceptor?
It is sensitive to changes in pH of the CSF as the CSF has a lower buffering capacity than blood.
What changes in gas does the central chemoreceptor respond to?
It responds to changes in PCO2 but not PO2
How does the central chemoreceptor respond to decreased pH?
It will increase in activity and increase ventilation
Where are the peripheral chemoreceptors found?
They are located in the aortic and carotid bodies
What changes are the peripheral chemoreceptors responsive to?
Decrease in pH (carotid bodies only)
Increase in PCO2
Decrease in PO2
What are the only chemoreceptors that respond to changes in PO2?
Peripheral chemoreceptors
Where are pulmonary stretch receptors located?
Within the smooth muscle cells of airways
What is the function of pulmonary stretch receptors?
Affect the activity of the inspiratory muscles based on stretch
What is the Hering-Breuer Inflation Reflex?
Inflation of the lung inhibits inspiratory muscle activity
What is the Hering-Breuer Deflation Reflex?
Deflation of the lung activates inspiratory muscle activity
Are the Hering-Breuer Reflexes active in adults?
Not so much
Where are the irritant receptors located?
Between airway epithelial cells
What is the role of irritant receptors?
They are stimulated by things like dust and smoke and are activated through the vagus nerve resulting in bronchoconstriction and hyperpnea
What are J receptors?
They are “juxtacapillary” receptors found in alveolar walls near capillaries that can trigger rapid shallow breathing
What are bronchial C fibers?
They respond to chemicals injected into bronchial circulation with rapid shallow breathing, bronchoconstriction and mucus secretion
What happens to ventilation as PCO2 increases?
It will increase
What happens to ventilation at a given PCO2 with lower PO2?
Ventilation will be higher than at a normal PO2
How will metabolic acidosis affect the response to CO2?
It will increase the response to CO2 by making the curve steeper
What is the most important stimulus for ventilation?
Arterial PCO2
At normal PCO2, how does the body respond to decreasing PO2?
PO2 can be reduced to 50 mmHg with normal PCO2 levels before ventilation will be induced. Therefore hypoxic stimulation plays only a small role in the increase in ventilation in healthy people.
At high PCO2 how does the body respond to decreasing PO2?
Ventilation will be induced much sooner at 100 mmHg
In patients with chronic severe lung disease, what is their primary stimulus for ventilation?
Hypoxia, or low PO2 because most of them will have chronic high PCO2
How does the body respond to metabolic acidosis?
Ventilation will be increased despite low PCO2
What mediates the ventilatory response to pH?
Peripheral chemoreceptors
What happens to the BBB at low pH?
The BBB becomes partly permeable to H+
What is the breathing pattern for obstructive sleep apnea?
Airflow is cut off but the pleural pressure continues to cycle, and increases as ventilation is not occurring.
What is the breathing pattern for central sleep apnea?
Brain activity to the lungs is stopped so that BOTH airflow and pleural pressure changes are stopped momentarily.
What is Kussmaul breathing?
It is deep breathing with normal or reduced frequency that is typical in severe acidosis, e.g diabetic ketoacidosis
What is apneustic respiration?
It is sustained periods of inspiration, followed by brief periods of exhalation with loss of input from vagal nerve and pneumotaxic center.
Probable causes are brain damage and intoxication.
What is Cheyne-Stokes ventilation?
Cyclic breathing with pauses before a waxing and waning and it repeats.
Often found with severe brain injury and patients near death.
What is Biot’s respiration?
Deep breaths with large pauses and is often due to neuronal damage
