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Review. What percentage of the atmosphere is below 18,000 ft.? What percentage of the atmosphere is oxygen? Nitrogen? Other? What is standard pressure in in. of Hg, Mb, and mm of Hg?

1) 50%
2) 21% oxygen 78% nitrogen 1% other
3) 29.92 inches, 760 mm, 1013.27 mb

1

What is true altitude?

altitude above standard datum plane

2

What is cabin altitude?

altitude equivalent pressure being maintained within the cabin. For non-pressurized- close to outside air pressure

3

What are the properties of gas?

- exerts pressure
- has mass
- is compressible

4

What is Boyle's Law and what is it's impact?

With a constant temp. volume has an inverse relationship with pressure.
Impact- as you increase altitude- pressure decreases, which means volume increases and gasses need released.

5

What are some effects of trapped gas when increasing altitude?

1) Barotitis- air trapped in teeth
2) Sinus block- air trapped in sinuses
3) Ear block- gas trapped in middle ear because of Eustachian tube blockage

6

What are the treatment options for trapped gas related issues involving ascents?

Teeth and Sinus- slow ascent, chew gum, swallow to open Eustachian tubes

7

What are some remedies for trapped gas problems dealing with descents?

Middle ears- slow descent, valsalva technique- pinch nose force air into ears, yawn and stretch neck

8

What is Charles' law?

Volume of gas is directly proportional to temp.

9

What equation derives from the combination of Charles' and Boyle's Law?

pv/T

10

What is Dalton's Law?

The total pressure of a mixture of gases is the sum of all partial pressures of gases

11

What is Henry's Law?

At equilibrium, a gas dissolved in liquid is proportional to the gas pressure.

12

What is decompression sickness?

Pain and effects from the release of gas out of solution and into the body.

13

Name and describe the three main types of decompression sickness.

1)The bends- most common (60%). Only symptom is pain. Mild to incapacitating. Remedied by descent.
2) Neurological- bubbles form in central nervous system (5-7%). Mostly brain, sometimes spine. Symptoms- headache, visual disturbance, fatique, emotional outburst (for brain). For spine- paralysis.
3) Creeps- skin and circulatory system. Feels like bugs.

14

Describe Frick's Law and how it relates in Aviation.

The rate at which a gas diffuses through a tissue medium is proportional to the tissue area and the difference between the partial pressures on either side of the tissue and inversely proportional to tissue thickness.
- More surface area for ir to go to lungs, the larger the differential pressures
- partial pressure in lungs greater than blood so O2 moves easily