Physiology of Flight

Physiology of Flight

Physiology of flight:how the human body functions during flight

Overview

1. Physiological Divisions of the Atmosphere2. Hypoxia and Hyperventilation3. Trapped Gases4. Decompression Sickness5. Principles and Problems of Vision6. Spatial Disorientation and Motion Sickness7. G-Forces8. Other Stresses of Flight

Physiological Divisions of the Atmosphere

Physiological ZoneSea Level to 10,000 feet

Region of the atmosphere in which there is enough oxygen to allow a normal, healthy person to fly without using special protectiveequipment

Physiological ZoneSea Level to 10,000 feet

May experience some dizziness or discomfort in the ears or sinusesA person can survive above 10,000 without an oxygen mask

Physiological-deficient Zone10,000 to 50,000 feet

This zone has reduced atmospheric and oxygen pressure, so the body must be supplied with supplemental oxygen and supplied under pressure at higher levels in this zone

Physiological-deficient Zone10,000 to 50,000 feet

Most military aircraft and commercial aircraft flying long distances go into this zone with protective equipment

Partial Space Equivalent Zone50,000 feet to 120 miles above

EarthThe atmospheric pressure is so low in this zone that a man would lose consciousness even if supplied with 100% oxygen under pressure

Partial Space Equivalent Zone50,000 feet to 120 miles above

EarthWhen flying in this zone, pilots must have a completely sealed space cabin with its own internally supplied oxygen and capability to remove carbon dioxide and to purify the air

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1. The physiology of flight is how the _ functions during flight:a. aircraftb. mindc. body

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2. Which zone allows a normal, healthy person to fly without using special protective equipment:a. partial space equivalentb. physiological-deficientc. physiological

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3. Most military and commercial aircraft flying long distances fly in this zone:a. partial space equivalentb. physiological-deficientc. physiological

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4. When flying in the higher levels of this zone, the body must be supplied with supplemental oxygen under pressure:a. partial space equivalentb. physiological-deficientc. physiological

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5. When flying in this zone, pilots must have a completely sealed space cabin with its own internally supplied oxygen:a. partial space equivalentb. physiological-deficientc. physiological

Effects of Reduced Pressure at Altitude

As the body goes to high altitudes it must make adjustments to the reduced atmospheric pressure in order to keep the flow of oxygen through the body cells and tissue constant. If the pressure outside the body is greatly reduced and the body is not adequately protected, it cannot make the necessary adjustments.

Hypoxia

Hypoxia - a state of too little oxygen in the body cells or tissue.• In flight it is usually caused by an insufficient

amount of oxygen in the inhaled air.• It impairs how the brain and other organs

function• May be aggravated by other conditions such

as anemia, poor circulation of the blood, or the presences of poison or alcohol in the body

Hypoxia

Greatest danger when pilot becomes engrossed in duties and doesn’t notice the first symptoms.First symptoms may include increased breathing rate, dimming of vision, headache, dizziness, poor coordinationand impairment of judgment, and finally the loss of visionand changes in behaviorAlso includes tunnel vision: a condition in which the edges if your sight gray out to a point where you only have a narrow field of vision straight ahead

Hyperventilation

Hyperventilation• A person affected by hypoxia tends to

increase breathing rate in an attempt to take in more oxygen.

• It is an abnormal increase in the volume of air breathed in and out of the lungs

• May continue to gasp until hyperventilation occurs

• May result from great emotional tension or anxiety.

Hyperventilation

Hyperventilation is simply over breathingSymptoms are similar to hypoxiaSymptoms include dizziness, hot and cold sensations, nausea, and finally unconsciousnessAfter the person loses consciousness, he no longer gasps for air the conditions corrects

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6. Over breathing:a. hypoxiab. hyperventilationc. trapped gases

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7. A deficiency of oxygen in the body cells or tissue:a. hypoxiab. hyperventilationc. trapped gases

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8. Which condition can lead to the other condition:a. hypoxia leads to hyperventilationb. hyperventilation leads to hypoxiac. either condition can cause the other

condition

Trapped Gases

As the body ascends and descends during flight, the free gases inside the body cavities expand or contract.Trouble develops when these gases cannot escape, or air from the outside cannot enter

Trapped Gases

Gases are most likely to be trapped in the ears, sinuses, teeth, stomach, and intestinesTrapped gases cause pressure to build up and the result may be pain and sickness

Ear BlockPressure develops in the middle ear when descent is made too quickly or when one is unable to equalize the pressure because the Eustachian tube is swollenThe Eustachian tube allows air to pass outward with ease, but resist passage of air in the opposite direction. During ear block, the process is not working

Ear Block

Air can usually be pushed through the Eustachian tube during descent by swallowing, yawning, or tensing the muscles of the throat at intervals, thus causing the pressure within the middle ear to equalizewith that of the outside pressure

Sinus Block

If an ascent or descent is made too quickly, or if the openings to the sinuses are blocked because the mucous membrane is swollen, pressure builds up within the sinuses and causes pain

Tooth Pain

• Gases may be trapped in the teeth at altitude in abscesses, imperfect fillings, and inadequately filled root canals

• The toothache often disappears at the same altitude that if was first observed on ascent.

Stomach and Intestines

• In flights above 25,000 feet the expandinggases in the stomach and intestines may cause severe pain, lowering blood pressure and eventually lead to shock.

• Usually results from air that has been swallowed.

• When pressure falls the partial pressures of the gases in the body fluids decrease.

• The escaping gases cause decompression sickness.

Decompression Sickness• Decompression sickness: a

condition resulting from exposure to low pressure that causes dissolved gases in the body to form bubbles

• Cause might be flying in unpressurized aircraft to high altitude or in aircraft that suddenly experiences decompression – the loss of cabin pressure – due to a malfunction or accident

The Bends

The Bends• Release of nitrogen

intothe joints of the body.

• Usually the joints ofthe knee and

shoulder

The Chokes

Another form of decompression sickness.* At first the pressure is felt as a deep burning sensation, but gradually it becomes a severe stabbing pain, aggravated by deep breathing• Deep, sharp pains under the

sternum.• Increased expansion of the lungs

causes the pain to increase.• Choking is caused by evolved gas

bubbles blocking blood vessels in the lungs

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 descentand 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.

Faintness, dizziness, and nausea may resultPerson could go into shock or become unconscious

Effects of Reduced Pressure at Altitude• Begin an emergency

descent and land as soon as possible

• If decompression sickness symptoms still exist after landing, compression therapy will be administered at the nearest hyperbaricfacility.

• The Air Force uses special chambers to train pilots to recognize symptoms of decompression sickness

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9. When gases inside body cavities cannot escape:a. hypoxiab. hyperventilationc. trapped gases

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10. This procedure can help get rid of __ by swallowing, yawing, or tensing the muscles of the throat at intervals:a. ear blockb. sinus blockc. tooth pain

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11. When the mucous membrane swells up, causing a build up of pressure and pain:a. ear blockb. sinus blockc. tooth pain

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12. This condition disappears during descent, at the same altitude it was first noticed during ascent:a. ear blockb. sinus blockc. tooth pain

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13. Small bubbles of nitrogen producing itching, hot & cold feelings, and tingling:a. the bendsb. the chokesc. stomach & intestinesd. the skin

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14. Release of nitrogen in the joints, usually the knee and shoulder, causing intense pain:a. the bendsb. the chokesc. stomach & intestinesd. the skin

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15. Expanding gases in flights above 25,000 feet, lowering the blood pressure, affects:a. the bendsb. the chokesc. the stomach & intestinesd. the skin

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16. A severe stabbing pain aggravated by deep breathing:a. the bendsb. the chokesc. stomach & intestinesd. the skin

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17. When decompression sickness becomes more severe, what should pilots should do immediately:a. alert the baseb. apply 100% oxygenc. go into shock

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18. If decompression sickness continues after landing, what treatment might be administereda. antibiotic treatment at a hospitalb. compression therapy in hyperbaric

chamberc. extended crew rest in pilot’s quarters

Vision

Aircrew members must be able to see well to judge speed and distances. Otherwise, they could not take off and land safelyIn addition, they must be able to distinguish colors to interpret signal flares and beaconsThey must also have good night vision to fly safely in the darkness

Night Vision

What happens when you go inside a dark theater after coming in from the bright sun?Can you see inside at first?How long does it take you to adapt?

Night Vision

Pilots experience a similar scenario trying to fly at nightThey use special goggles with red lenses to help keep the eyes ready to adjust to the darkThey also fly by instruments, versus trying to see land marks

Factors Affecting Visions

Glare: windshield and windows protectOxygen deprivation: reduces visual acuityIllumination: cockpits have white lights to reduce shadows and glareIllusions: staring at objects too long can cause. Pilots scan objects to prevent

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19. Aircrew members must be able to see well to judge:a. time and speedb.dates and distancec. speed and distances

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20. Aircrew members must be able to distinguish colors to interpret:a.signal flares and traffic lightsb.airports and beaconsc. signal flares and beacons

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21. Aircrew members use special goggles with what color lenses to keep the eyes ready to adjust to the dark?a.whiteb.redc. yellow

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22. Airplane cockpits are illuminated with what color lights to help reduce shadows and glare?a.whiteb.redc. yellow

Spatial Disorientation

Spatial disorientation: the lack of knowing an aircraft’s position, attitude, and movement It is the inability to accurately orient yourself with respect to the Earth’s horizon.

Motion SicknessMotion sickness: a product of the brain receiving conflicting messages about the body’s true positionA disagreement with what the body feels and what the eyes seeIf your body has ever been spun rapidly in a circle and then suddenly stopped, if you watch and/or feel the motion of waves while on a body of water, or even if your car is sitting still and you look at objects moving past your car and get the sensation of moving, you may have experienced motion sickness

Spatial Disorientation & Motion Sickness

The body uses three systems that work together to figure out position, attitude, and movement:– Visual system: eyes sense position based on what they

see– Vestibular system: inner ear organs sense position by the

way the body is balanced– Somatosensory system: nerves in the skin, muscles, and

joints – along with hearing – sense position based on gravity, feeling, and sound

The brain pieces all of this info together, and when the three systems agree, the brain can accurately determine position, attitude, and movement

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.

• Use of flight instruments is a sure way to help confirm the position of the horizon

Spatial Disorientation and Motion Sickness

Brought about because the balance mechanisms in the inner ear have been affected by inertia (resistance to change in motion).As a result, the hair filaments do not sense the movement of the fluid in the semicircular canals in the normal way – motion is not registered

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.

Spatial Disorientation and Motion Sickness

The Air Force uses special equipment to help determine a pilot’s threshold of tolerance for spatial disorientation and motion sickness

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23. Lack of knowing the aircraft’s true position, attitude, or movementa.spatial disorientationb.motion sicknessc. balance impropriety

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24. Inability to accurately orient oneself with respect to the Earth’s horizona.spatial disorientationb.motion sicknessc. balance impropriety

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25. A product of the brain receiving conflicting messages about the body’s true positiona.spatial disorientationb.motion sicknessc. balance impropriety

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26. Nerves in the skin, muscles, and joints – along with hearing – sense position based on gravity, feeling, and sounda.visual systemb.vestibular systemc. somatosensory system

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27. Inner ear organs sense position by the way the body is balanceda.visual systemb.vestibular systemc. somatosensory system

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28. Eyes sense position based on what they seea.visual systemb.vestibular systemc. somatosensory system

Acceleration and Deceleration: Increased G-Forces

G-force: a measure of gravity’s accelerativeforceA change in an aircraft’s speed or motion(dives, turns for example) can induce G-forcesSteep turns and dives can generate a force of acceleration that is many times the force of gravity

Acceleration and Deceleration: Increased G-Forces

Linear acceleration: a change in speed in a straight line = takeoff, landing, and straight flightRadial acceleration: a change in direction = sharp turns, dives, pulling out of a diveAngular acceleration: simultaneous change in both speed and direction = spins and climbing turns

G-Forces

The three types of accelerations induces three types of G-forces on the bodyGx: acts on the body from the chest to the back;

-Gx occurs during takeoff when A/C gain speed, pushes pilot back into the seat

+Gx: the force from the back to the chest during landings, pushes the pilot forward in the shoulder strap

Gy: a lateral force that acts from shoulder to shoulder; encountered during aileron rolls on the longitudinal axisGz: a force that acts on the body’s vertical axis = head to foot and foot to head

- Gz is applied from head to foot, as when pulling out of a dive+Gz is applied from foot to head, as when in a dive

Positive G-Force

Blood rushes from the head toward the feet, just as the normal gravity force does when a person is in a standing position on the ground.In flight, a positive G-Force is experienced when the aircraft is entering a high speed turn or pulling out of a steep diveThe cardiovascular system has to react quickly to keep blood flowing to the brain

Negative G-ForceThe blood rushes from the feet to the head, or as gravity would act upon a person standing on his head.In flight, negative G-Forces are rare, but would occur when an aircraft is diving at a high rate of speedWhen a pilot goes into a dive, blood can’t flow back down through the veins into the heart, yet the arteries are carrying more blood than ever to the head

G-Force

+G-force warning signs: progressive loss of vision, onset of tunnel vision, gun barrel vision, gray out, then black out of all vision; if the accelerating G-forces continue, the pilot may finally pass out-G-force warning signs: red out (pilots see a field of red), loss of consciousness

G-Force

The Air Force provides pilots a G-suit to help equalize the effects of increased G-ForcesG-suit: a piece of clothing that protects pilots from the effects of G-forcesThe G-suit prevents blackouts by applying pressure to the legs and abdomen to keep blood pressure up and blood circulating to the brain

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29. G-force is a measure of gravity’s __ force:a.stallb.accelerativec. decelerated

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30. A change in an aircraft’s __ or __ can induce G-forcesa. stalls and accelerationb. speed and motionc. longitudinal and vertical dips

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31. Simultaneous change in both speed and direction:a. linear accelerationb. radial accelerationc. angular acceleration

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32. A change in direction:a. linear accelerationb. radial accelerationc. angular acceleration

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33. A change in speed while traveling in a straight line:a. linear accelerationb. radial accelerationc. angular acceleration

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34. Occurs when an aircraft is entering a high speed turn or pulling out of a steep dive, the blood rushes from the head to the feet:a. normal G-forceb. negative G-forcec. positive G-force

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35. Under normal conditions, a force is exerted upon the body and acting in a direction toward the center of Earth:a. normal G-forceb.Negative G-forcec. Positive G-force

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36. When an aircraft is diving at a high rate of speed, the blood rushed from the feet to the head:a. normal G-forceb.Negative G-forcec. Positive G-force

Other Stresses of Flight

Alcohol• One drink at 10,000 feet

can have the same effect as two or three drinks at sea level.

• Can affect coordination, limit vision, impact memory, reduce reasoning power, slow reflexes, and lower attention span

Other Stresses of Flight

Tobacco• It raises the

concentration of carbon monoxide in blood

• Results include reduced ability to see clearly and adapt eyes to the dark

Self-Imposed Stresses

Drugs• Aspirin, nasal

decongestants, tranquilizers or sedatives.

• Side effects such as drowsiness, loss of balance, and nauseacan occur faster

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37. Use of this product can affect coordination, limit vision, impact memory, reduce reasoning power, and slow reflexesa. alcoholb. tobaccoc. drugs

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38. This product raises the concentration of carbon monoxide in the blood, resulting in reduced ability to see clearly and adapt eyes to the dark

a. alcoholb. tobaccoc. drugs

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39. This product raises the concentration of carbon monoxide in the blood, resulting in reduced ability to see clearly and adapt eyes to the dark

a. alcoholb. tobaccoc. drugs

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40. Side effects of this product if used when flying includes drowsiness, loss of balance, and nausea

a. alcoholb. tobaccoc. drugs

Summary

1. Physiological Divisions of the Atmosphere2. Effects of Reduced Pressure at Altitude3. Trapped Gases4. Decompression Sickness5. Principles and Problems of Vision6. Spatial Disorientation and Motion Sickness7. G-Forces8. Other Stresses of Flight