Breathlessness and Control of Breathing (awake) Flashcards
Is tidal expiration an active or passive process?
Passive - due to the natural recoil of the lungs
State the equation for minute ventilation.
VE = VT x Frequency Frequency = 60/TTOT (if you want it per minute)
How can this equation be manipulated to include TI?
VE = VT/TI x TI/TTOT
What does VT/TI represent?
Neural Drive - mean inspiratory flow
What does TI/TTOT represent?
Inspiratory Duty Cycle
Proportion of the cycle spent actively ventilating (i.e. breathing in)
How do these factors change when there is an increase in metabolic demand?
Increased metabolic demand —> increased ventilation
VT/TI = INCREASE
TTOT = DECREASE (increase frequency)
TTOT is decreased by a combination of reduction in TI and TE
What is the normal tidal volume and normal minute ventilation?
Tidal Volume = 0.5 L
Minute Ventilation = 6 L/min
Breathing Rate = 12 breaths per minute
What changes take place if you use a noseclip?
Breathe more DEEPLY - increase in VT
Breathe SLOWER - decrease in frequency
Ventilation remains the SAME
What changes take place when artificial dead space is added?
Compared to with mouthpiece only: Minute ventilation = INCREASE VT = INCREASE Frequency = INCREASE VT/TI = INCREASE
How is the breathing of someone with COPD different to a normal person?
Breathing is SHALLOWER and FASTER
What changes when we exercise?
Increases neural drive and hence ventilation Increases frequency (decrease TTOT)
Where is the voluntary and involuntary control of breathing located?
Voluntary = Cerebral Cortex Involuntary = Medulla
How is the metabolic controller reset in sleep?
PCO2 rises
Where, in the motor homunculus, is behavioural control of breathing located?
Between the hip and the trunk
Which receptors are involved in regulating the involuntary control of breathing?
HYDROGEN ION RECEPTORS found in the carotid bodies and in the metabolic centre itself