Respiratory Physiology: Ventilation Control Flashcards
Ventilation control require stimulation of what muscles during inspiration
Skeletal
Where does ventilation control occur via
Phrenic (to diaphragm) and intercostal nerves (to external intercostal muscles)
Where does ventilation control reside
ill-defined centres located in the pons and medulla
What is PRG and what does it modulate
Pontine respiratory group located in the Pons and it modulates DRG and VRG
What does VRG and DRG stand for
Ventral Respiratory Group and Dorsal Respiratory Group
What does VRG control
Expiration (tongue, pharynx and larynx)
What does DRG control
Inspiration (via phrenic and intercostal muscles)
What are the 4 basis’ of rhythm of respiration
- Emotion (via limbic system)
- Voluntary over-ride (via higher centres in the brain)
- Mechano-sensory input from the thorax (stretch reflex to prevent over-expansion)
- Chemoreceptors which detect chemical composition of the blood (PCO2, PO2 and PH)
Which of the 4 basis of rhythm is the most significant
Chemoreceptors
Where is the central chemoreceptor located
Medulla
What is the stimuli which activates the central chemoreceptor
Responds directly to H+ (directly reflects PCO2)
Where do these changes occur and how does this effect the ventilatory drive
Occurs in the CSF. CO2 combines with H20 to form carbonic acid and H+ and is the primary ventilatory drive
Hypercapnea
Raised PCO2 in CSF
Does the central chemoreceptor respond directly to changes in the plasma (Y/N)
N
What crosses the blood brain barrier when PCO2 in arterial blood increases?
H+