Aeromedical Flashcards
Visual system
- most important for maintaining equilibrium and orientation
- orientation information equals to 80% from visual system
Vseri ulnar system
- Inner ear
- simi-circular canals filled with endolymph fluid
- otoliths organs
- cupula
Types of spatial disorientation
- type 1 (unrecognized)
- type 2 (recognized)
- type 3 (incapacitating)
Spatial disorientation
Defined
Individuals inability to determine his position, attitude, and motion relative to the surface of the earth or significant objects.
Motion parallax
Objects that appear to be moving rapidly are judged to be near while those moving slowly are judged to be a greater distance away.
Aerial perspective
Fading of colors or shades
Loss of detail or texture
Position of light source and direction of shadow
Retinal image size
Known size of objective
Increasing/decreasing size of object
Terrestrial association
Overlapping contours
Geometric perspective
Linear perspective
Apparent foreshortening
Vertical position in the field
Monocular cues
Geometric perspective
Retinal image size
Aerial perspective
Motion parallax
Peripheral vision
- rods used w/ what type of vision
- what method should be used for increasing night vision
- stimulation of only rod cells is primary for viewing during scoot pic vision
- to compensate for scoot pic vision aircrew members must use off-center viewing
Night blind spot
- occurs when the fovea becomes inactive under low level light conditions
- 5-10* wide in center of fov
- object will b gin to fade when stared at for longer than 2 seconds
Types of vision
Photopic- experienced during daylight (cones only)
Mesopic- dawn, dusk, full moonlight (rods and cones)
Scotopic- low-light level environment. Visual acuity decreased to 20/200 or less.
Day blind spot
- Compensated for by binocular vision
- covers 5.5-7.5 degrees
- located about 15 degrees from the fovea and originates where the optical nerve attaches to the retina
Night vision
- what chemical is utilized?
- how long to adapt?
- rhodopsin must build up in rods
- adaptation takes from 30-45 min
- rod cells are 10,000 times more sensitive
- –through a dilated pupil, light sensitivity may increase 100,000 times
Rhodopsin
-what color?
- visual purple
- not always in rods b/c light bleaches it out
Iodopsin
-what cells is it present in
- always present within the cone cells
- cone cells respond immediately to visual stimulation regardless of ambient light levels
How many rod cells and where are they
120 million rod cells in the retina
Rod cells, what type of vision
Used for night or low-level intensity light vision
Cone cells
-what type of visoion
Principally for day or high intensity light vision
Visual deficiencies
Myopia- near sightedness
Hyperopia- caused by an error in refraction(farsightedness)
Astigmatism- unequal curvature of the cornea
Presbyopia- aging process (the lens hardens)
Is the physiological effects of g acceleration more pronounced in the lateral or vertical aces
Lateral
Vision is completely lost before a loss of consciousness occurred at ____ g’s?
4
Unconsciousness can result when a force of ___ g’s is applied to the body
5
Types of fatigue
Acute- physical or mental activity between two sleep periods
Chronic- more serious over a longer period and is the result of inadequate recovery from successive periods of acute fatigue
Motivational exhaustion or burnout- chronic fatigue that goes untreated for too long
Self imposed stressors
Drugs - self medication - overdose - allergic reaction - synergistic effects - caffeine - predicted side effects Exhaustion Alcohol Tobacco - a smoking aviator begins at 5000 ft Hypoglycemia
Stress
Nonspecific response of the body to any demand placed on it
Trapped gas disorders of the teeth
Barodontalgia
Generally occurred from 5000-15000 ft
Descent almost invariably brings relief
Prevention and treatment of trapped gases
During flight- crew embers can equalize pressure during descent by swallowing or yawning or valsalva
(Never valsalva during ascent)
Dysbarism
Various manifestation of gas expansion induced by decreased baro pressure
Stages of hypoxia
Indifferent 98-90% 0-10,000 ft
Compensatory 89-80% 10-15,000 ft
Disturbance 79-70% 15-20,000 ft
Critical 69-60% 20-25,000 ft
Susceptibility to hypoxia
- onset time and severity
- self imposed stress
- ascent rate
- physical activity
Histotoxic hypoxia
There is an interference with the use of O2 by body tissue
- alcohol
- narcotics
Stagnant hypoxia
Circulation is inadequate but oxygen carrying capacity of the blood is adequate
- heart failure
- arterial spasm
Hypemic hypoxia
A reduction in the oxygen carrying capacity of the blood
- anemia
- blood loss
- carbon monoxide
Hypoxic hypoxia
Not enough oxygen in the air or decreasing atmosphere pressure prevents the diffusion of O2
Principle role of the white blood cell
To fight/control various disease conditions, especially those caused by invading microorganism
Oxygen is transported by
Red blood cells
-erythrocytes
Average adult volume of blood
5 liters or above 5% of total weight
Night vision begins to decrease at what altitude
4000 ft
How often is hypo arid refresher training
Every 5 years
Treatment for spatial d
Dr. t
Delay intuitive reactions
Refer to the instruments and develop good cross check
Transfer controls
Prevention of spatial d
Never fly vfr and ifr
Never fly without visual reference
Avoid self imposed stressors
Trust the instruments
Never, never, avoid, trust
Vestibular illusions
Somatogyral
- the leans
- graveyard spiral
- coriolis illusion
Somatogravic
- oculogravic
- Oculoagravic
- Elevator illusion
Visual illusions
False horizons Fascination/fixation (4-20 cycles) Flicker vertigo Confusion w/ ground lights Relative motion Altered planes of reference Structural illusion Height/depth perception Crater illusion Size/distance Auto kinesics Reversible perspective
Proprioceptive systems
Sensation resulting from pressure on joints, muscles, and skin
