Physiology of Flight

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Physiology of Flight

• Know the physiology of flight.
• 1. State the layers of the atmosphere and the
  composition of each.
• 2. Describe the physiological divisions of the
  flight environment.
• 3. Define the physical laws of gases according
  to Boyles Law, Daltons Law, and Henrys Law.

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Physiology of Flight

• Know the physiology of flight.
• 4. Describe the processes for respiration and
  circulation.
• 5. State the effects of reduced pressure at
  altitude.
• 6. Define spatial disorientation and motion
  sickness.
• 7. Describe individual stresses imposed upon a
  pilot during flight.

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Overview

• 1. Nature of the Atmosphere
• 2. Respiration and Circulation
• 3. Effects of Reduced Pressure at Altitude
• 4. Rapid Decompression
• 5. Principles and Problems of Vision

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Overview

• 6. Spatial Disorientation and Motion Sickness
• 7. Acceleration and Deceleration
  Increased G-Forces
• 8. Noise and Vibration
• 9. Heat and Cold During Flight
• 10. Noxious Gases and Vapors
• 11. Self-Imposed Stresses

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Physiology of Flight
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Nature of the Atmosphere

• Composition of the atmosphere
• 78 nitrogen, 21 oxygen, 1 carbon dioxide.
• Nitrogen is not used by body to support life.
• Blood and other body fluids contain nitrogen.
• Blood carries oxygen to all parts of the body.
• Oxygen decreases at higher altitudes.

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Nature of the Atmosphere

• Layers of the atmosphere
• Troposphere
• Most weather occurs in this region
• Stratosphere
• Very little moisture
• Ionosphere
• Major characteristic-ionization
• Exosphere
• 600 to 1,200 miles above Earth

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Physiological Divisions of the Atmosphere
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Nature of the Atmosphere

• Physiological Divisions
• Physiological zone
• Extends from sea level to 10,000 feet
• Physiological-deficient zone
• Extends from 10,000 to 50,000 feet
• Space-equivalent zone
• Extends from 50,000 feet to 120 miles above Earth
• Total space-equivalent zone
• Beyond 120 miles above Earth

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Nature of the Atmosphere

• Physical Laws of Gases
• Boyles Law
• The volume of a gas is inversely proportional to
  its pressure if the temperature remains constant.
• Daltons Law
• The total pressure of a mixture of gases is equal
  to the sum of the partial pressure of each gas in
  that mixture.
• Henrys Law
• The amount of a gas in a solution varies directly
  with the partial pressure that gas exerts on the
  solution.

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Respiration and Circulation

• Respiration is the exchange of oxygen and carbon
  dioxide between an organism and its environment.
• Closely related to circulation of blood
  throughout the body.

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Respiration and Circulation

• Decreasing oxygen pressure places stress on the
  body affecting the respiratory system first.
• Made up of the lungs, bronchi and their small
  branches, windpipe, mouth, and the nose.
• Air enters the nasal passages where it is warmed
  and moistened and foreign matter removed.

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Respiration and Circulation
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Respiration and Circulation

• The amount of carbon dioxide in the blood has an
  important effect on the action of the heart.
• As carbon dioxide in the blood increases, the
  heart rate speeds up so the heart can send more
  oxygenated blood to the tissues.
• When carbon dioxide in the blood decreases, the
  heart rate slows because tissues need less
  oxygen.

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Respiration and Circulation

• The respiratory system acts to keep the amount of
  oxygen in the body tissues constant.

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Effects of Reduced Pressure at Altitude

• As the body goes to high altitude it must make
  adjustments to the reduced atmospheric pressure
  in order to keep the body tissue constant. If
  the pressure outside the body is greatly reduced
  and the body is not adequately protected, it
  cannot make the necessary adjustments.

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Effects of Reduced Pressure at Altitude

• Hypoxia - a deficiency of oxygen in the body
  cells or tissue.
• Most frequently the result of decreased pressure
  on an unprotected body.
• In flight is usually caused by an insufficient
  amount of oxygen in the inhaled air.
• Greatest danger when pilot becomes engrossed in
  duties and doesnt notice the first symptoms.

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Effects of Reduced Pressure at Altitude

• Hyperventilation
• A person affected by hypoxia tends to increase
  breathing rate in an attempt to take in more
  oxygen.
• May result from great emotional tension or
  anxiety.

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Effects of Reduced Pressure at Altitude

• Trapped Gases-Ear Block

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Effects of Reduced Pressure at Altitude

• Trapped Gases-Sinus Block

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Effects of Reduced Pressure at Altitude

• Trapped Gases-Tooth Pain
• Untreated cavities where pulp is exposed may be
  the cause of tooth pain at altitude.
• The toothache often disappears at the same
  altitude that if was first observed on ascent.
• Gases may be trapped in the teeth at altitude in
  abscesses.

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Effects of Reduced Pressure at Altitude

• Trapped Gases-Stomach and Intestines
• In flights above 25,000 feet the expanding gases
  may cause severe pain, lowering blood pressure
  and eventually shock.
• Usually air that has been swallowed.
• When barometric pressure falls the partial
  pressures of the gases in the body fluids
  decrease.
• The escaping gases cause decompression sickness.

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Effects of Reduced Pressure at Altitude

• The Bends
• Release of nitrogen into
• the joints of the body.

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Effects of Reduced Pressure at Altitude

• The Chokes
• Another form of decompression sickness.
• Deep, sharp pains under the sternum.
• Increased expansion of the lungs causes the pain
  to increase.

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Effects of Reduced Pressure at Altitude

• Skin Symptoms
• Type of decompression sickness that involves
  sensations of the skin.
• Small bubbles of nitrogen under the skin produce
  itching, hot and cold feelings and tingling.
• The rash does not disappear with descent and may
  last for hours.

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Effects of Reduced Pressure at Altitude

• Treatment of Decompression Sickness
• As decompression sickness becomes more severe,
  the pain caused by escaping gas bubbles becomes
  more intense.
• As symptoms appear in flight, 100 oxygen should
  be administered.
• If symptoms still exist after landing,
  compression therapy will be administered at the
  nearest hyperbaric facility.

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Rapid Decompression

• Rapid decompression at a high altitude brings on
  an explosion as the pressure suddenly decreases.
• At 63,000 feet or above body fluids boil if
  exposed to the ambient atmosphere.
• The time of useful consciousness may be reduced
  by 60 if the decompression is rapid and the air
  is forced out of the lungs due to rapid expansion.

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Principles and Problems of Vision
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Spatial Disorientation and Motion Sickness

• Spatial disorientation - the inability to
  accurately orient yourself with respect to the
  Earths horizon.
• We use four sensory systems to maintain our
  orientation and equilibrium (balance).

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Spatial Disorientation and Motion Sickness

• The Visual System
• Eyes provide the strongest and most reliable
  orientation information during flight.
• When the horizon is not correct, your vestibular
  disorientation disappears you may still
  experience visual illusions caused by false
  horizon.

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Spatial Disorientation and Motion Sickness

• The Vestibular System

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Spatial Disorientation and Motion Sickness

• The Vestibular System

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Spatial Disorientation and Motion Sickness

• The Somatosensory System
• Consists of tactile pressure receptors in the
  skin, muscles, tendons and joints.
• Often called the seat-of-the-pants sense.

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Acceleration and Deceleration Increased G-Forces

• When military flight crews perform maneuvers or
  when astronauts are launched or recovered they
  may be subjected to severe stress from the
  effects of acceleration and deceleration.
• The stresses are felt as increases in weight or
  gravity forces (G-Forces).

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Acceleration and Deceleration Increased G-Forces
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Noise and Vibration

• Cause flyers more inconvenience than any other
  factor in flight.
• Sound intensity or loudness is measured in
  decibels.
• Vibrations are measured in frequency.
• One effect of vibration is blurred vision.

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Heat and Cold During Flight

• The largest amount of heat is generated on the
  skin of aircraft and spacecraft as it travels at
  high speeds through the atmosphere.
• An aircraft flying at Mach 2 has skin
  temperatures increased by about 400o F as a
  result of aerodynamic heating.
• There are two dangers associated with exposure of
  the body to cold.

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Noxious Gases and Vapors

• Inside an enclosed cabin, noxious gases and
  vapors may accumulate.
• The breathing atmosphere can easily become
  contaminated from inside sources if care is not
  taken.
• Carbon Monoxide.

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Self-Imposed Stresses

• Alcohol
• One drink at 10,000 feet can have the same effect
  as two or three drinks at sea level.
• Tobacco
• Smoking at 10,000 feet produces effects
  equivalent to those experienced at 14,000 feet
  without smoking.
• Drugs
• Aspirin, nasal decongestants, tranquilizers or
  sedatives.

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Summary

• 1. Nature of the Atmosphere
• 2. Respiration and Circulation
• 3. Effects of Reduced Pressure at Altitude
• 4. Rapid Decompression
• 5. Principles and Problems of Vision
• 6. Spatial Disorientation and Motion Sickness

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Summary

• 7. Acceleration and Deceleration Increased
• G-Forces
• 8. Noise and Vibration
• 9. Heat and Cold During Flight
• 10. Noxious Gases and Vapors
• 11. Self-Imposed Stresses