Physiology of Flight Know the physiology of flight. 1. Describe the physiological divisions of the...

Physiology of Flight

Know the physiology of flight.

1. Describe the physiological divisions of the flight environment.

2. Define the physical laws of gases according to Boyle’s Law, Dalton’s Law, and Henry’s Law.

Physiology of Flight

Know the physiology of flight.

3. Describe the processes for respiration and circulation.

4. State the effects of reduced pressure at altitude.

5. Define spatial disorientation and motion sickness.

6. Describe individual stresses imposed upon a pilot during flight.

Overview

1. Respiration and Circulation2. Effects of Reduced Pressure at Altitude3. Rapid Decompression4. Principles and Problems of Vision

Overview

6. Spatial Disorientation and Motion Sickness

7. Acceleration and Deceleration: Increased G-Forces

8. Noise and Vibration9. Heat and Cold During Flight

10. Noxious Gases and Vapors 11. Self-Imposed Stresses

PRE-TEST

VOCABULARY:Physiology = the organic processes or

functions in an organism or in any of its parts.

VOCABULARY:Hypoxia = deficiency in the amount of oxygen delivered to the body tissues

VOCABULARY:Valsalva = a maneuver to clear your ears to

equalize pressure

VOCABULARY:M-1 = a maneuver to constrain your vessels and muscles to keep blood from rushing to

your feet during G-loads

Physiology of Flight

REVIEW: 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

Physiological Divisions of the Atmosphere

DRAW THIS IN YOUR NOTES!

• 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

Nature of the Atmosphere

• Physical Laws of Gases• Boyle’s Law

• The volume of a gas is inversely proportional to its pressure if the temperature remains constant.

• Dalton’s Law• The total pressure of a mixture of gases is equal to

the sum of the partial pressure of each gas in that mixture.

• Henry’s Law• The amount of a gas in a solution varies directly with

the partial pressure that gas exerts on the solution.

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.

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.

Respiration and Circulation

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.

Respiration and Circulation

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

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.

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 doesn’t notice the first symptoms.

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.

Effects of Reduced Pressure at Altitude

• Trapped Gases-Ear Block

Effects of Reduced Pressure at Altitude

• Trapped Gases-Sinus Block

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.

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.

Effects of Reduced Pressure at Altitude

• The Bends• Release of nitrogen into

the joints of the body.

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.

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.

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.

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.

Principles and Problems of Vision

Spatial Disorientation and Motion Sickness

• Spatial disorientation - the inability to accurately orient yourself with respect to the Earth’s horizon.

• We use four sensory systems to maintain our orientation and equilibrium (balance).

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.

Spatial Disorientation and Motion Sickness

• The Vestibular System

Spatial Disorientation and Motion Sickness

• The Vestibular System

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.

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).

Acceleration and Deceleration: Increased G-Forces

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.

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.

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.

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.

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

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