Challenges to normal respiration Flashcards
How much oxygen is needed per minute at rest?
200ml/min aka 1 MET
What is VO2 max?
The level work at which oxygen consumption no longer increases (anaerobic respiration.)
Plateau on graph. Measure of how fit an individual is.
Is VO2 max improvable?
Yes
What can VO2 max be used for in a medical setting?
Assesing whether a patient will survive surgery
What 6 factors control change in oxygen consumption (VO2)?
Psychological factors Neural input to the respiratory centre Proprioceptors ABG changes Cardiovascular changes Temperature regulation
What is the most potent driver of respiration- lack of O2 or build up of CO2?
Build up of CO2
What is atmospheric pressure at sea level?
101.3 kPa
What is alveolar pressure of O2 at sea level?
13.3 kPa
To work out alveolar pressure of oxygen you multiply partial pressure of O2 by (_____ minus _______)
Atmospheric pressure by partial pressure of water (6.3kPa)
What happens to alveolar pressure of oxygen at altitude?
It decreases
What is the body’s response to altitude? (5 things)
- Hyperventilation and so compensatory respiratory alkalosis
- Increased 2,3-DPG so more O2 released by Hb
- Polycythaemia (higher blood count)
- Bicarbonate excretion from CSF and kidneys
- Diuresis and hyponatraemia
What happens to the acid/base balance of the body at altitude?
Respiratory acidosis due to build up of CO2
What are 5 symptoms of altitude sickness?
- Headache
- Nausea
- Loss of apetite
- Difficulty sleeping/exercising
- Amnesia/dizziness
How do you treat altitude sickness?
Acetazolamide
Rapid descent
What are 2 severe complications of mountain sickness?
- Cheyne Stokes respiration
2. Cerebral/pulmonary oedema
How much does a 10m descent underwater increase atmospheric pressure?
1 atm
What is the affect of descent underwater on partial pressure of oxygen?
It increases the ppO2
What is the affect of increaed pressure on the chest and abdomen?
They are compressed
Is it the descent or ascent that is a problem when diving?
Ascent due to reduction in ppO2 so hypoxia.
What sort of oxygen is used at great depth when diving?
helium-oxygen. May be 2% O2 but at that pressure this still represents 20kPa
At what depth does ‘the bends’ become a risk? What is necessary to prevent it?
> 40m, slow ascent with compression chamber
What is the dive reflex?
Innate in many mammals- underwater they spontaneously hold their breath, slow HR and peripheral vasoconstriction.
What causes decompression sickness?
Nitrogen dissolved in tissues which forms bubbles upon ascent.
What is the scientific name for the bends?
Decompression sickness