Control Of Breathing Flashcards
What is the average gas exchange at rest
250ml of O2/min and -200ml CO2 - breathing is highly stable
What is the gas exchange when walking 3mph
800ml O2/min and 750ml/min CO2
what is the gas exchange when intense exercise is taking place
5000 ml O2/min and 6000ml/min CO2
What two things send the brain neural signals
Chemoreceptors and mechanoreceptors
What is the function of chemoreceptors
Provide feedback on blood PO2 and PCO2 and pH
What is the role of mechanoreceptors
Provide feedback on the mechanical status of lungs, chest wall and airways
What does the brain send neural signals to to control breathing
- respiratory muscles to produce rhythmic breathing movements
- upper airway muscles eg laryngeal, pharyngeal and tongue
- produce reflexes to keep airways patent eg cough sneeze ect
What part of the brain controls breathing
The brainstem
What do chemoreceptors detect
They detect changes in partial pressure of oxygen and carbon dioxide and also the pH in blood
What are peripheral chemoreceptors
Peripheral chemoreceptors are small highly vascularised bodies in region of aortic arch and carotid sinuses, information is sent via the glossopharyngeal and vagus nerves to the nucleus in the brainstem called NTS
What are decreases in oxygen referred to as
Hypoxia
What are increases in carbon dioxide referred to as
Hypercapnia
What do peripheral chemoreceptors respond to
Decreases in partial pressure of oxygen (hypoxia)
What partial pressure would oxygen have to drop to to have a significant effect
Below about 60mmHg at which there would be a progressive hyperventilation
What are central chemoreceptors
Clusters of neurones in the brainstem that are activated when PCO2 is increased (hypercapnia) or pH decreased
What causes central chemoreceptors to become activated
Increase in arterial PCO2
Explain the ventilatory response to hypercapnia
Very small changes in PCO2 have large effects on ventilation (unlike O2)
Hypercapnic response originates in central chemoreceptors in the brainstem
Plays a major role in moment to moment control of breathing
What are mechanoreceptors
Sensory receptors that detect changes in pressure, movement and touch
In the respiratory system mechanoreceptors detect movement of lung and chest wall
What activates mechanoreceptors
Inflation of the lungs
What nerve sends neural signals from mechanoreceptors to the brainstem
The vagus nerve
What part of the brainstem are signals sent from mechanoreceptors to
Signals are sent from mechanoreceptors to the nucleus tractus solitarius in the brainstem
Where are mechanoreceptors found in the respiratory system
They are found in airways smooth muscle and airway epithelium
What generates the rhythm of breathing
A cluster of respiratory neurones in the brainstem generate rhythm of breathing
What sends information to the NTS
The NTS recieves information from mechanoreceptors and peripheral chemoreceptors
What neurons are active during inspiration
Inspiratory neurones
What neurons are active during expiration
Expiratory neurones
What does the phrenic nerve innervate
Innervates the diaphragm
