Aviation Physiology and Atmospheric Science

Comprehensive flashcards covering atmospheric layers, gas laws, types of hypoxia, decompression sickness, visual and vestibular systems, and toxic substances encountered in aviation.

Troposphere

The layer of the atmosphere from $0$ to approximately $66,000\,FT$ where all weather (Wx) occurs.

Stratosphere

The atmospheric layer extending from $66,000\,FT$ to $160,000\,FT$ which contains the ozone layer.

Standard Temperature Lapse Rate

The rate at which temperature decreases in the troposphere, defined as $-1.98^\circ\text{C}$ per $1000\,FT$..

Atmospheric Gas Composition

A mixture containing $78\%$ Nitrogen ($N_2$), $21\%$ Oxygen ($O_2$), and $1\%$ remainder gases.

Physiological Zone

The altitude range from $0$ to $10,000\,FT$.

Physiologically Deficient Zone

The altitude range from $10,000$ to $50,000\,FT$ where supplementary $O_2$ is required.

Space Equivalent Zone

Altitudes above $50,000\,FT$ requiring pressurization, sealed suits, and $100\%$ $O_2$.

Mean Sea Level (MSL) Pressure

A total pressure of $760\,mmHg$, with the partial pressure of Oxygen ($P_{O2}$) being $160\,mmHg$.

Graham's Law

A gas law mentioned in the context of the protective effects of the atmosphere and gas behavior.

Chemoreceptors

Sensors that detect chemical content in the body, primarily sensing the partial pressure of $CO_2$ to control breathing.

Mechanoreceptors

Sensors that measure how big the lungs are by sensing stretch.

Hypoxic Hypoxia

A lack of oxygen caused by reduced diffusion of oxygen from the alveoli to the blood.

Hypaemic Hypoxia

Reduced oxygen-carrying capability of the blood, often caused by Carbon Monoxide ($CO$) poisoning.

Stagnant Hypoxia

A lack of oxygen caused by reduced flow of blood, which can be due to $G$-forces or cold.

Histotoxic Hypoxia

A reduced ability of the tissues to utilize oxygen, often caused by Hydrogen Cyanide ($HCN$).

Time of Useful Consciousness (TUC)

The period of time from the reduction of oxygen supply until mental effectiveness is impaired.

Hyperventilation

Breathing faster and deeper than needed for the removal of carbon dioxide, which can lead to a reduction in $CO_2$ levels in the alveoli.

The Bends

A type of decompression illness involving joint pains caused by nitrogen bubbles evolving from the blood.

The Chokes

Chest pain and breathing difficulty caused by nitrogen bubbles trapped by the lungs.

The Staggers

A neurological condition affecting the brain and spinal cord due to nitrogen bubbles.

Rods

Photoreceptors used for peripheral and night vision that are sensitive to movement but have poor color vision.

Cones

Photoreceptors located in the fovea used for central, sharp detail and color vision in high-light (photopic) conditions.

Empty Field Myopia

A condition where the eyes default to a focus of approximately $2\,m$ when there are no distant cues or horizontal references.

Saccadic Vision

The rapid flicking movement of the eyes which may cause targets to be missed or retinal images to blur.

Semicircular Canals (SSC)

The three-axis circular accelerometers in the inner ear that detect angular acceleration.

Otolith Organs

The part of the inner ear sensitive to linear acceleration and gravity.

The Leans

The most common vestibular illusion where a pilot feels a false sensation of bank because of a sub-threshold roll detection.

Somatogravic Illusion

A confusion between linear translation and tilt, such as the 'Dark Night Takeoff' illusion where acceleration is perceived as an upward pitch.

Coriolis Illusion

An illusion caused by the cross-coupling of different semicircular canals when moving the head out of the plane of a turn.

Flicker Vertigo

A false sense of rotation in the opposite direction caused by a rotating or flickering light source.

Alternobaric Vertigo

Vertigo caused by a pressure difference between the left and right middle ear.

Liquid Oxygen (LOX)

A cryogenic substance stored at $-182.95^\circ\text{C}$ that can cause cold burns and severe frostbite.

Carbon Monoxide (CO)

A colorless, odorless, and tasteless gas that binds more readily to hemoglobin than oxygen does.

Hydrogen Cyanide (HCN)

A highly toxic histotoxic gas that inhibits cells from using oxygen.