Control of Breathing Flashcards
Part 2
What are the main components of the respiratory system?
The respiratory system includes the nose, pharynx, larynx, trachea, bronchi, bronchioles, and lungs.
What is the primary function of the respiratory system?
The respiratory system’s primary function is gas exchange—the intake of oxygen (O2) and removal of carbon dioxide (CO2).
What controls breathing at the central level?
Breathing is controlled by the medulla oblongata and pons in the brainstem, which regulate the rate and depth of breathing.
What role do peripheral chemoreceptors play in breathing?
Peripheral chemoreceptors, located in the carotid and aortic bodies, monitor changes in blood oxygen (O2), carbon dioxide (CO2), and pH.
What is hypoxia?
Hypoxia refers to a deficiency in the amount of oxygen reaching tissues.
What is hypercapnia?
Hypercapnia is an excessive amount of carbon dioxide in the bloodstream, often caused by inadequate respiration.
How is breathing initiated?
Breathing is initiated by rhythmic impulses from the respiratory centers in the medulla and pons, which send signals to the respiratory muscles.
What is the function of the dorsal respiratory group (DRG)?
The DRG integrates sensory input from chemoreceptors and regulates the inspiratory muscles during quiet breathing.
What is the function of the ventral respiratory group (VRG)?
The VRG controls forced expiration and active inspiration during exercise or distress.
What is the role of the pneumotaxic center?
The pneumotaxic center in the pons helps coordinate the transition between inspiration and expiration by limiting inspiration duration.
What inputs modify respiratory rhythms?
Respiratory rhythms are modified by higher brain centers, such as the cerebral cortex (voluntary control) and the hypothalamus (emotional changes).
What is the role of the apneustic center?
The apneustic center stimulates the inspiratory neurons to prolong inspiration and delay expiration.
How do baroreceptors, thermoreceptors, and mechanoreceptors influence breathing?
These receptors provide feedback on blood pressure, temperature, and lung stretch, influencing respiratory rate and depth.
What is the primary stimulus for central chemoreceptors?
Central chemoreceptors, located in the medulla, are primarily sensitive to changes in PaCO2 (carbon dioxide levels) and pH in cerebrospinal fluid (CSF).
How do peripheral chemoreceptors respond to hypoxia?
Peripheral chemoreceptors in the carotid and aortic bodies respond to low PaO2 by increasing their firing rate, stimulating ventilation.
What is the relationship between PaCO2, PaO2, and ventilation?
An increase in PaCO2 strongly stimulates ventilation, while a significant decrease in PaO2 enhances the response, creating a synergistic effect.
How do central chemoreceptors respond to changes in CSF pH?
Central chemoreceptors detect changes in CSF pH, reflecting changes in PaCO2, and adjust breathing to maintain stable levels of CO2.
What is the role of the ventral respiratory group (VRG) during exercise?
During exercise, the VRG becomes active, increasing both inspiratory and expiratory muscle activity to meet the body’s higher oxygen demands.
How does the dorsal respiratory group (DRG) receive input?
The DRG receives sensory input from the IXth (glossopharyngeal) and Xth (vagus) cranial nerves and adjusts the breathing rhythm accordingly.
What happens to ventilation during emotional stress?
Emotional stress activates the hypothalamus and limbic system, causing changes in breathing rate and depth, often leading to hyperventilation or breath-holding.
What effect does oxygen therapy have on patients with chronic hypercapnia?
In patients with chronic hypercapnia, high levels of O2 can depress the carotid body’s hypoxic drive, potentially causing dangerous hypoventilation.
How does chronic hypercapnia affect chemoreceptor sensitivity?
In chronic hypercapnia, chemoreceptors adapt by reducing their sensitivity to elevated CO2, leading to reliance on hypoxia for ventilation control.
How do the carotid bodies respond to changes in PaO2?
The carotid bodies respond to dramatic decreases in PaO2 by increasing ventilation, but they are less sensitive to changes in oxygen content.
What is the primary response of central chemoreceptors to hypercapnia?
Central chemoreceptors strongly stimulate ventilation when PaCO2 increases, producing about 80% of the ventilatory response to rising CO2.
