altitude Flashcards
what are the body’s reactions to an altitude of 1524m
Light sensitivity decreases by 5%
what are the body’s reactions to an altitude of 3048m
25% decrease in light sensitivity, 30% decrease in visual acuity, 25% decrease in attention
what are the body’s reactions to an altitude of ~4000 - 4500m
15% decrease in cognition, 33% decrease in postural stability, 25% decrease in pursuit tracking, 20% decrease in recall.
equation for partial pressure of Oxygen
Oxygen pressure = O2 %/100. * barometer pressure
1 bar in mm Hg (Torr)
750 Torr
what are the thresholds for:
High altitude, very high altitude and extreme altitude?
1500-3500m high altitude
3500-5500m very high altitude
>5500: extreme altitude
what is the altitude limit for habituation?
Limit for habituation ±5820m-5985m
what are the major problems with altitude (on the human body)
Acute mountain sickness (AMS)
High altitude pulmonary edema (HAPE)
High altitude cerebral edema (HACE)
Chronic mountain sickness
High-altitude retinal haemorrhage
what are the first reactions a body uses to compensate for low oxygen?
Hyperventilation
Increased blood flow during rest and submaximal exercise.
Fluid loss (increases haemoglobin per L)
what happens to VO2 max at high altitude
VO2 max decreases
what are the longer-term adjustments to altitude that the body makes
Stroke volume and maximal heart rate decrease (SV decreases slowly, compensated by overall heart rate increasing)
Cardiac output lowers
Greater arterio-venous pO2 pressure
Regulation of acid base balance (correct for high pH due to hyperventilation)
* Synthesis of haemoglobin and red blood cells (erythropoietin [EPO]);
* local circulation (higher muscle cappillarisation; disputed, possibly caused by
muscle wasting) & cellular function;
* Slight shift of HB dissociation curve to right (2,3 DPG) in tissues
* Increased myoglobin (+16%),
* Reduced # of mitochondria, especially at extreme altitude and highland natives
* plasma volume decrease
* Reduced lean body mass and fat (depressed appetite and
reduced efficiency intestinal absorption
* Acclimatisation: 2 weeks to 2300 +1 week per 610m to 4600; loss 2-3 weeks
What are the issues with altitude training
Maximal cardiac output is reduced
Training intensity is decreased
But oxygen delivery is improved
What are the basic altitude training choices
Live high train high
Light high train low
Live low train high
What models can be used in Live High Train Low altitude training
Supplemental oxygen, Nitrogen dilution, Oxygen filtration, natural or terrestrial options
what are the primary pollutants in air pollution
Carbon monoxide, sulfur monoxides, nitrogen oxides, hydrocarbons and particulates
What are the secondary pollutants in air pollution
Ozone, aldehydes, sulfuric acid and peroxy-acetyl nitrate
what gases does the air tend to be composed of
Nitrogen(78%), oxygen(21%), argon(~1%), carbon dioxide(0.03%)
what units are used in reference to pollution
PPM
1% = 10,000ppm
what are the attack routes for pollution?
Through the skin or through the respiratory system (mouth/nose, respiratory tract - then blood and tissues)
What are the effector mechanisms of pollution?
Irritation of the airways, reduction of alveolar diffusion capacity, reduction of oxygen transport capacity, eye irritation, skin irritation
what is the equation for dosage
Dose = concentration x time x ventilation
what are the sources of Carbon Monoxide?
Car exhausts, combustion heating, cigarettes
What effect does carbon monoxide have?
Forms carboxyhaemoglobin (more readily binds to haemoglobin than O2 does)
Reduces the release of oxygen in tissues
Also binds to myoglobin and cytochromes in mitochondria (blocks ATP formation)
what concentration of CO leads to 12% Carboxyhaemoglobin after 8 hrs
100ppm
What effect does CO have on VO2 max
VO2 max reduces with increased concentration of COHb (Carboxyhaemoglobin)
Beyond what concentration do sulfur oxides start to effect the body
3 ppm
Every 10m (of depth) of water adds how many atmospheres of pressure
1 ATM
what is Boyle’s Law
P1 x V1 = P2 x V2
if gas takes up 10 Litres at 1 ATM, what does it take up at 10 ATM, 5 ATM and 1/2 of an ATM?
10 ATM - 1L
5 ATM - 2 L
1/2 ATM - 20L
What is Dalton’s Law
The pressure exerted by a gas mixture is equal to the sum of the pressures which each of the gases would exert if it alone occupied the space filled by the mixture
Using Dalton’s Law, what would the partial pressure of oxygen be at 1,2 and, 3 ATM. (assuming normal air was taken to those pressures.)
1 ATM - PO2 = 1 x 0.209 x 760 mm Hg = 159 mm Hg
2 ATM PO2 = 2 x 0.209 x 760 mm Hg = 318 Hg
3 ATM PO2 = 2 x 0.209 x 760 mm Hg = 476 mm Hg
What is Henry’s Law
If the partial pressure of a gas in a liquid is reduced, the amount of that gas which can be held in solution will be reduced in proportion
What causes shallow water blackout?
When Partial pressure of O2 in the blood goes below 30mm Hg
how many additional litres of nitrogen are dissolved into the body for every 10m of water depth
1 Litre
What causes the bends
Dissolved nitrogen in the blood boiling and becoming bubbles in the bloodstream, blocking blood vessels.
When do the bends tend to occur
They tend to occur in scuba dives, or breath-hold dives that are repeated too close together
How long do the people of the Mangareva Island leave between dives
10 Minutes
Do people with low body fat absorb less nitrogen while underwater than High body fat
Yes, people with high body fat absorb more nitrogen than people with low body fat
What can be caused by increased pressure underwater
Air embolisms, Face mask squeeze, Blockage of eustachian tube, blockage of sinus openings, mediastinal and subcutaneous emphysema, pneumothorax and, alveoli rupturing
What other problems can occur when diving deep
Lungs can swell on the ascent,
Body density increases with depth and so after 7m you sink rather than float.
Pressure can cause diuresis on immersion and after-cooling on exit
What problems are there with using nitrogen in compressed air cylinders
Nitrogen narcosis, the presence of nitrogen in the air breathed can cause nitrogen narcosis which at 50m can make divers feel inebriated but can kill at 90m
The scuba limit tends to be 30m
What does oxygen poisoning do
Irritated respiratory passages
Destroys lining of alveoli
Constricts cerebral blood vessels and alters central nervous system function
Blunts CO2 elimination
Why isn’t pure oxygen used at depth
It can cause oxygen poisoning, particularly while pressurised
What are the unique risks in scuba diving
Increased resistance to breathing with increased density of compressed gas mixture at depth
Toxicity of oxygen at high pressure
Anesthetic effects of nitrogen at high pressure
excess heat loss from environmental stress and inhaled gas mixture
free-gas development in gas saturated body tissues
What can happen with to the body with carbon dioxide at pressure
High CO2 can lead to high breathing rate, headaches, confusion, loss of consciousness
What replaces nitrogen in air tanks when diving at depth, and why?
Helium, it causes less narcosis and is less soluble. It is lighter and less viscous.
Unfortunately it has higher conductivity and so leads to heatloss.
And it causes donald duck voice.
How long does it take to decompress after a saturation dive to 100m
Approximately 4 days
What are the long term health effects of deep saturation diving?
Joint pain, bone degeneration, hearing loss(due to bubble formation), brain damage/ lesions in brain.
what is the normal pull of earth gravity
+1g
what is 1g equal to
1g = 9.8m/s2
how do you get negative gs
Standing on your head exposes you to -1g on earth
what is increased positive g referred to as
(eyeballs in)
what are the effects of increased positive g
2g - Heavy/ sagging face
3g - standing impossible (3x body weight)
4.5g - sight loss but no issues with hearing or cognition
8g - no raising of arms or legs
12g - loss of consciousness
Which people are more sensitive to increased g
Taller people
What do Horizontal seats enable the body to do
Withstand up to 15G instead of 12G
what countermeasures are there against positive g
Horizontal seats, breathing and straining exercises (to force blood and fluids to keep circulating)
The libelle anti G-Suit which is a skin-tight suit that contains fluid that follows the G-force, and forces the blood out of the areas it moved into
What is negative g referred to as
Eyeballs out - because it feels like your eyeballs are being forced out of your skull
what is negative g characterised by
The blood moving to the head and causing small blood vessels in the eyes to bulge and sometimes burst
what is the main problem with rocket launches (besides g force)
VIbration causes discomfort, reduced manual task performance, nausea and body resonance. (which can cause physical collapse and hyperventilation)
what is the force of gravity on the moon
0.1654g
how does the introduction of microgravity affect blood pressure
It causes the loss of hydrostatic gradient, blood pressure becomes closer to equal across the body and this causes facial puffiness and birdlike legs
What happens when you return from microgravity
overall blood pressure is low, although blood pressure is back to being higher in the legs than the rest of the body. This causes faintness
How does microgravity affect red blood cells
Microgravity causes a decrease in red blood cells and total haemoglobin
How does microgravity affect stature
Stature has been seen to be increased by up to 4cm by microgravity.
What happens to stature after returning to earth
On return to earth, stature returns to normal or in some cases decreases after recovery.
How is posture affected by microgravity?
In microgravity, posture becomes hunched over. This is then also displayed, to a lesser extent, upon return to earth.
How does microgravity affect bodyweight?
Bodyweight decreases after a couple of days in microgravity, it then returns to normal upon recovery on earth.
What are the bodily changes in microgravity
Fluid loss
smaller heart
loss of bone mass
loss of muscle mass
loss of muscle strength
postural control/ eye movements
What does motion sickness do
It increases heat loss in a cool environment
It decreases arterial pressure and g tolerance by 0.5g
What countermeasures are there to the cardiovascular effects of microgravity
Fluid and electrolyte replenishment
exercise
lower-body negative pressure (machine that applies slight vacuum to lower-body)
What countermeasures are there to the neuro vestibular effects of microgravity?
Intramuscular promethazin
Adaptation trainers
What countermeasures are there to the musculoskeletal effects of microgravity?
Dieting
exercise (strapped to a treadmill)
How quickly do the different systems take to reset? (Fluids, neuro vestibular, red blood cell mass, lean body mass, cardiovascular system)
Fluids and electrolytes - 1 week
neuro vestibular - 1.5 weeks
red blood cell mass - 4 weeks
lean body mass - 2 months
cardiovascular system - up to 4 months
what pressure are space suits pressurised to
1/3 atm
why is oxygen poisoning not a problem in space, considering 100% O2 is used.
The suits are pressurised to 1/3 ATM meaning the pO2 is not great enough to cause O2 toxicity
How many layers of physical protection are in a space suit, and how much does it weigh
14 layers, 113kg
what temperature range are space suits exposed to which on space walks
+120C to -100C
