L84: Control of Breathing Flashcards
Breathing maintains blood gas homeostasis, what are the factors to this?
O2, CO2 and pH
What are the partial pressures of O2 and CO2 at rest?
O2: 100±2, CO2: 40± mmHg
What are the exchange rates of O2 and CO2 at rest?
O2: 250, CO2: 200 mL
What are the exchange rates of O2 and CO2 at 3mph walking?
O2: 800, CO2: 750 mL
What are the exchange rates of O2 and CO2 during severe exercise?
O2: 5000, CO2: 6000 mL
What kind of receptors does the brain recieve neural signals from?
Chemoreceptors and mechanoreceptors
What changes do chemoreceptors detect?
Chemical changes - PO2, PCO2 and pH in blood
Where are peripheral chemoreceptors located?
Aortic arch and carotid sinuses
Which cranial nerve do the chemoreceptors in the aortic arch send/ receive information?
CNX - vagus nerve
Which cranial nerve do the chemoreceptors in the carotid sinuses send/ receive information?
CNIX - glossopharyngeal nerve
A decrease in PO2 (hypoxia) is detected by:
Peripheral chemoreceptors
A decrease in PO2 (hypoxia) leads to…
Increased ventilation (to restore PO2)
A increase in PCO2 (hypercapnia) is detected by:
Central chemoreceptors
A decrease in pH is detected by:
Central chemoreceptors
An increase in PCO2 (hypercapnia) leads to…
Increased ventilation (to restore PCO2)
At what partial pressure are hypoxic conditions detected to lead to a hyper-ventilatory response?
60mmHg
Which gas’ partial pressure plays an important role in moment to moment breathing control?
PCO2 - much more sensitive than PO2.
What changes do mechanoreceptors detect?
Pressure, movement and touch - movement of the lungs and chest wall
Where are mechanoreceptors located?
Airways smooth muscle and epithelium
Which cranial nerve do mechanoreceptors send/ receive information?
CNX - vagus nerve
What do mechanoreceptors on smooth muscle of the airway’s respond to?
Inflation and distension of the airways
What do mechanoreceptors on smooth muscle of the airway’s lead to?
Termination of breathing
What do mechanoreceptors in epithelium of the airway’s respond to?
Rapid lung inflation, deflation or oedema
What do mechanoreceptors in epithelium of the airway’s lead to?
Sigh or shortened expiration
Where is the respiratory rhythm generated?
The brainstem
Which respiratory neurones are active during inspiration?
Inspiratory neurones
Which respiratory neurones are active during expiration?
Expiratory neurones
Where are rhythmic neural signals sent to?
The spinal cord and then respiratory muscles
Where does the phrenic nerve exit the spinal cord?
C3-5
What region of the spinal cord innervates intercostal muscles?
Thoracic
How is the respiratory centre organised?
- 2 x respiratory neurone groups in the medulla oblongata;
1 x respiratory neurone group in the pons
What are the two groups of respiratory neurones in the medulla oblongata?
- Dorsal respiratory group;
- Ventral respiratory group (NTS).
Where are rhythmic neural signals sent from?
Ventral respiratory group (NTS) of the brainstem
Where do chemoreceptors and mechanoreceptors send neural signals (of detected changes) to?
The nucleus tractus solitarius (NTS), in the brainstem
Where is information, detected by chemo- and mechanoreceptors, processed?
Neurones in the brainstem
