L5 - ventilation and its control. Flashcards

1
Q

How are the respiratory gases (O2 and CO2) are transported between the atmosphere and mitochondria.

A

Alveolar Ventilation - mass flow of air driven by pressure gradient. air going in and out of lungs.
Alveolar-blood transfer. Diffusion flow of each gas. Driven by pressure gradient of each gas. oxygen entering the alveoli.

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2
Q

what determines alveolar ventilation?

A

(tidal volume - dead space) x repspiratory rate.
abut dead space does not help with breathing.

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3
Q

anatomical vs phyiological dead space

A

Anatomic dead space is due to the structure of the respiratory tract.
Physiologic dead space happens when some alveoli don’t exchange gases efficiently.

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4
Q

what controls alveolar ventilation?

A

inspiratory duration, focre, frequency and resistance. e.g. depper breathing pattern will increase alveolar ventilation.

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5
Q

how is ventilation controlled?

A

Controlled by rhythmic inspiratory neurons - Located in the medial medulla that send inspiratory impulses to inspiratory muslces.
Cycle modified by several excitatory and inhibitory stimuli (both neural and humoral) thatact on the respiratory centre in the medulla.

turned off by themselves and adjacent expiratory nuerons.

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6
Q

Ventilatory control at REST chemoreceptors.

A

mainly by chemoreceptors (detect chemical state of arterial blood).

Central chemoreceptors - locatedin hte medulla, highly sensitive to co2, regulate the blood from knowing that.

peripheral chemoreceptors: carotid and aortic bodies. located in carotid artery and aorta. not as sensitve but reposnd to pH, o2 and co2 levels.

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7
Q

Ventilatory control (at REST) o2 and co2

A

Ventilation is much more sensitive to co2 than o2. okay beacuse if 02 is low, co2 is usually high. but not more some things (hyper ventilation when co2 is low but o2 is normal)

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8
Q

Ventilatory response (with time) during sustainable exercise.

A

3 phases in exercise.
1 - rapid increase of Ve
2 - exponential
3 - plateau (light to moderate exercise only)
recovery - immediate drop with stopping. after time it will become slower slope.

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9
Q

Ventilatory control in exercise

A

po2 and pco2 not major factor. NEUROGENIC FACTORS DOMINATE IN EXERCISE:

  1. central command (feedforward control) Motor cortex output “spill-over” irradiates medulla ensuring it receives input. Contribute esp. to Phases 1 & 2 of hyperpneoa response to exercise, and to rapid decline at end exercise
  2. muscle ‘ergoreceptors’ (feedback control) mechanoreceptors in early phases. metaboreceptors - phase 3 = fine tuning.
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10
Q

Respiratory responses to non-sustainable exercise.

A

Ventilation
* Rises rapidly
* Disproportional to oxygen use
* Fails to stabilise
* Stays elevated in recovery (likely driven by
acidosis in muscle and blood)

CO2 production rises markedly. Produce more CO2 than O2 used* i.e., VCO2 > VO2. * This excess CO2 is produced by way of buffering H+ from muscle: CO2+ H2O H2CO3 H+ + HCO3

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11
Q

Ventilation also affected during resistance exercise

A

increased expiratory force during exertion. also block glottis espically at >80% MVC. increase in central venous and arterial pressures. increased risk for blackout.

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12
Q

what is block glottis

A

This maneuver involves forcibly exhaling against a closed airway, effectively blocking the glottis (the opening between the vocal cords in the larynx) to create intra-abdominal pressure.

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13
Q

fitter people and respiratory profile. and reasons

A

given relative ex load athletes have less increased ve and less acitdity.
reasons
- decrease in tyoe 2 fibres
- increase recruit of type 1 fibres and increase h+ buffering.

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