Physiology Flashcards
Atmosphere
•Atmospheric Gases
•Oxygen 21% (Life support)
•Nitrogen 78% (Inert)
•Others 1% (Argon, Helium)
•Percentages do not change with altitude
•Pressure changes with altitude
Why does pressure change with altitude
Caused by the weight of the atmosphere being supported above you.
Temperature
•Troposphere Lapse Rate (SL to FL350)
•2.0° Centigrade per 1,000ft
•3.5° Fahrenheit per 1,000ft
•Stratosphere (FL350 to 50 miles altitude)
•Temperature is relatively constant
•-55° Centigrade
Physiological divisions
•Normal Adaptation
•SFC to 10,000ft MSL
•Decreased pressure does not impair performance
•Physiologic deficiency
•10,000ft to FL500
•Humans are unable to adapt
•Oxygen or Pressurization equipment is needed.
Henry’s law
The amount of dissolved gas in a solution is proportional to the partial pressure of gas over the solution.
•Ex: To put CO2 into soda, they put a high pressure of CO2 above the liquid, which causes it to dissolve into the liquid.
•When you open the can, pressure above goes away and the amount of CO2 begins to decrease (as bubbles) until your soda is flat
Same thing occurs when Scuba diving
•High pressure on your body dissolves Nitrogen from lungs and into the blood and tissue
•If you come up too quickly, pressure drops and bubbles form in your body (very painful)
•A decrease in pressure could lead to bubbles
Dalton’s law
Total barometric pressure is equal to the sum of each component of gas.
•Oxygen + Nitrogen + Others = Barometric pressure
•As pressure is reduced, expansion of gases creates increasing distances between molecules and the quantity of oxygen decreases per breath
•The pressure of each gas can be isolated, and is known as partial pressure.
•Partial pressure = (total pressure) (% of gas)
Hypoxia
Lack of sufficient oxygen in the body cells or tissues by:
•inadequate supply of oxygen
•inadequate transportation of oxygen –or-
•inability of the body tissues to use oxygen.
Hypoxic
Optimal function of the brain requires 96% oxygen saturation.
•Affects to human performance begin at 87% oxygen saturation
•At 12,000ft MSL, brain oxygen saturation is approximately 87%
•Recommended to use oxygen above 10,000ft (day) or 5,000ft (night) due to your visions sensitivity to a lack of oxygen.
When is oxygen required
12,500 MSL- crew after 30 min
14,000 MSL- crew
15,000 MSL- crew plus must be provided to passengers
Histotoxic
Inability of the body tissues to utilize oxygen because of impaired cellular respiration.
•Caused by:
•Alcohol
•Drugs
•You have enough Oxygen but your body can’t use it properly
•Cannot be corrected with the use of supplemental oxygen
Hypemic
A reduction in the oxygen-carrying capacity of the blood.
•Contamination of red blood cells or hemoglobin by gases other than oxygen.
•Caused by:
•Smoking
•Carbon monoxide (CO) poisoning
Stagnant hypoxia
Oxygen deficiency in the blood resulting from poor circulation of the blood because of a failure of the circulator systems.
•Caused by:
•Coronary artery disease
•Excessive G-Forces
Signs of hypoxia
Behavioral Changes
•Poor coordination
•Discoloration at the fingernails (cyanosis)
•Sweating
•Headache
•Fatigue
•Loss of vision
•Tingling or warm sensations
Decompression sickness
Trapped Gas
•Abdominal pain
•Toothache
•Middle Ear
•Sinuses
•Evolved Gas
•Bends
•Chokes
•Paresthesia (bubbles in the central nervous system)
Boyles law
The volume of a gas is inversely proportional to its pressure.
•Approximate gas expansion
•FL165 2:1
•FL300 5:1
•FL430 9:1
•FL500 17:1
