Transcript Flight Physiology

Aviation Human Factors
LECTURE 2: FLIGHT PHYSIOLOGY
1
Learning Objectives
By end of this session, you will be able to:
• Understand how the body and mind can be
affected in flight as well as why they are affected
in flight.
• Be knowledgeable about the physiology of the
body in the flight environment.
Why Important?
• Flight physiology and human factors both
have an impact on flight.
• More than 70 percent of aviation accidents
and incidents are in some way related to
human factors.
• An accident is one incident too many.
• No accident occurs without a series of
incidents happening beforehand.
What is Physiology?
The study of human systems' integrated
functions and the processes by which they
maintain the body functions.
Flight physiology
• Flight physiology is how the body and mind work in
the flying environment.
• It includes
– How our organs function,
– What keeps them from functioning in a abnormal
environment,
– What the pilot can do to protect these functions before
and during flight.
• Flight physiology, therefore, is an integral part of
human factors and safe flight, and it has a direct
effect on human performance.
Remember
• Knowing flight physiology, being aware of its
effects on performance, and maintaining a
high index of suspicion when performance
becomes poor will continue to make everyone
a better and safer pilot.
• Suspicion = a feeling that something is
possible
SHELL Model
• Model developed by ICAO
• This model explain why the physiology of flight is
important, since the human element is obviously
crucial and central and every aspect of physiology
will affect every other interaction as defined in the
model.
• Human factors are how these interfaces and
interactions ultimately affect performance.
SHELL MODEL
H
S
L
L
E
L- L I V E W A R E (Human)
• Core of the model
comprised of human
operators, most flexible
and critical component
in the system.
S - Software (procedures, documentation)
H - Hardware (technology, machine,
equipment)
E - Environment (weather, temperature, noise
L - Liveware (human)
Objectives of
Understanding Flight
Physiology
• To prevent incapacitation or impairment,
whether mental or physical .
• Incapacitation incapable of performing
expected normal activity.
• Mental incapacitation is the mind’s inability
to use proper judgment, reasoning, and
decision making.
Incapacitation
• Beyond that, mental incapacitation turns into
“neurological” incapacitation, whereby the
signals from the brain fail to use the sensory
information and data from the eyes, ears,
touch, smell, and the like.
• Physical incapacitation refers to the body’s
inability to function in an expected way.
• The end result of both mental (mind) and
physical (body) incapacitations is an unsafe
and poorly performing pilot.
Human Body System
Human Body System
• Respiratory System
• Circulatory System
• Nervous System (Brain)
Respiratory System
• Respiration is the exchange of gases between
the body and its tissues and the outside
ambient air.
• The main objective of respiration is to add
oxygen and remove carbon dioxide.
Functions of Respiratory
System
 Intake of Oxygen [O2]
 Removal of Carbon Dioxide [CO2]
 Maintenance of body heat balance
 Maintenance of body acid base balance [pH]
Respiration
Breathing out
Breathing in
diaphragm
descends
diaphragm
relax
Active Phase
INHALATION
• air inflates the lungs
Passive Phase
EXHALATION
• air is forced out
What is the
functions of
Human Lung?
The Lung
• Function of Lung: To transport of oxygen to
the rest of body.
• Exchange oxygen O2 and Carbon Dioxide CO2 .
The Lung
• Air enters through
the nose, mouth,
trachea to the
bronchial tree.
• Distribute to the
ALVEOLI (air sacs),
where blood brought
with OXYGEN
molecules.
• Amount of OXYGEN
from Alveoli into red
blood cells depends
on pressure gradient.
The Lung
• Within the red blood cell, there is
Hemoglobin, which function as specialized
oxygen transport system that allows far more
oxygen to be carried by blood
• At high altitude, we need to increase rate and
depth of breathing in order to get enough
oxygen into our lung.
Effects of reduced Pressure
• As the pressure decreases at high altitude the
movement of oxygen into the blood is
impaired.
• The result is hypoxia , or oxygen deprivation.
Hypoxia
• State of blood when it has an not enough
supply of oxygen for the requirements of the
tissues and body cells
• This can cause impairment of body function
especially brain.
• Death will follow if oxygen lack continues.
Pressure Decrease With
Altitude
PRESSURE
ALTITUDE
FEET
mm/HG
ATMOSPHERES
0
760
1
18,000
380
1/2
34,000
190
1/4
48,000
95
1/8
63,000
47
1/16
Pressure Decrease With
Altitude
• The air pressure is 30% lower at
the higher altitude due to the
fact that the atmosphere is less
dense--that is, the air molecules
are farther apart.
Circulation System
FUNCTIONS:
• Carries the blood, which in turn transports oxygen,
carbon dioxide, nutrients, and waste products.
• Assists in temperature regulation.
REMEMBER
• Any change in oxygen levels to the cells immediately
changes the performance of many organs, especially
the brain
Low pressure effect to
Vascular System
• At high altitudes, the lower air pressure makes
it more difficult for oxygen to enter our
vascular systems.
Vascular
System
• The link between the
heart, lungs, brain,
and other parts
(blood vessels)
• Function: To
maintain blood
supply to all tissues
of the body
The Heart
The heart is an organ
that pumps the
blood through the
circulatory system
by contraction and
dilation.
The Heart at high Altitude
• At higher altitudes, our bodies initially
develop inefficient physiological responses.
• There is an increase in breathing and heart
rate to as much as double even while resting.
• Pulse rate and blood pressure go up sharply as
our hearts pump harder to get more oxygen
to the cells.
• These are stressful changes, especially for
people with weak hearts.
The Heart at high Altitude
• The heart muscle requires oxygen for energy
• The heart can fail or become less effective if
oxygen does not reach the heart muscle.
• Total blockage of blood to the heart muscle
leads to death of some of the tissues
• Dead heart tissue lead to heart attack.
The Brain
1st Part of Brain (4 lobes)
-Frontal lobes: thoughts, decisions,
and judgments
-Parietal lobes: senses and send
information for processing.
-Temporal lobes: Speech center
location and where the brain
computes information (for written
and spoken communications).
-Occipital lobes: are where
information from the eyes is
processed.
The Brain
• 2nd part of brain (Midbrain): Hypothalamus,
which produces hormones that affect
temperature, growth, and other physiological
activities.
• 3rd part of brain (Hindbrain): The center of
regulation of many of the body’s basic
functions, including breathing, blood pressure,
heart rate, and many others.
Effect of lack oxygen to Brain
Lack of oxygen to the brain, lead to the failure of
the brain function such as
• Inability to do normal physical activities,
• Distorted vision
• Difficulty with memorizing
• Difficulty in judgment and decision making
• Loss of thinking ability
• Fail to communicate and write well
TYPES OF HYPOXIA
Hypoxic Hypoxia
A deficiency
in Alveolar
oxygen
exchange
Reduced
pO2
in the lungs
(high
altitude)
Red
blood cells
Body tissue
Hypoxic Hypoxia
• Hypoxic hypoxia occurs when not enough oxygen is
in the air or when decreasing atmospheric pressures
prevent the diffusion of O2 from the lungs to the
bloodstream.
• The partial pressure of oxygen as it is presented to
the blood within the lungs is too low to effectively
carry and transfer enough oxygen to the cells of the
tissues.
Hypemic Hypoxia
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
An oxygen
deficiency due
to reduction in
the oxygen
carrying
capacity of the
blood
Hypemic Hypoxia
• Hypemic hypoxia is caused by a reduction in the
oxygen-carrying capacity of the blood.
• Can cause anaemia, a condition in which there is a
deficiency of red cells or haemoglobin in the blood.
• Means less capacity for blood to carry
oxygen.
• Hemoglobin (Hgb) physically carries 75 times more
oxygen molecule.
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Adequate
oxygen
Blood
moving
slowly
Stagnant
Hypoxia
Reduced
blood
flow
Red blood cells
not replenishing
tissue needs
fast enough
Stagnant hypoxia
• In stagnant hypoxia, the oxygen-carrying capacity of the
blood is adequate but, circulation
is inadequate.
• Such decrease in blood flow results from the heart failing to
pump effectively.
• Such conditions as heart failure, arterial problem, and
blockage of a blood vessel predispose the individual to
stagnant hypoxia.
• More often, when a crew member experiences extreme
gravitational forces, disrupting blood flow and causing the
blood to stagnate.
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Histotoxic Hypoxia
Adequate
oxygen
Inability of the
cell to accept
or use oxygen
Red blood cells
retain oxygen
Poisoned tissue
Histotoxic Hypoxia
• Histotoxic means the target cell expecting and
needing oxygen is abnormal and unable to take up
the oxygen that is present.
• This abnormality has been created as a result of a
toxins present/absorbed by the cell (ex: Alcohol
becomes a toxin to the cell)
• Alcohol, narcotics, and certain poisons interfere
the use of Oxygen by body tissues.
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Importance to know hypoxia
• No matter what the reason for oxygen not getting to the cell
the lack of oxygen (hypoxia) results in a variety symptoms.
• The danger of hypoxia is that the pilot is probably
unsuspecting that he/she is hypoxic.
• The key to flying safe at high altitude is to recognize:
– The conditions under which you could be hypoxic.
– The physical and mental symptoms that indicate you are
hypoxic.
– When a crewmate is susceptible to hypoxia in those
conditions.
Why important to
recognize?
• Because the nervous system tissues have a heavy
requirement for oxygen, especially the brain (and eyes), most
hypoxic symptoms are directly or indirectly related to the
nervous system (brain).
• If hypoxia is prolonged, serious problems develop with
ultimate death . In extreme cases (prior to death), some brain
cells are actually killed, and they cannot be regenerated.
• The single most dangerous characteristic of hypoxia is that if
the crewmember is hypoxic and engrossed in flight duties, the
pilot might not even notice the impairment.
Symptoms of hypoxia
• Apparent personality change – change in
outlook and behavior
• Impaired judgment – loss of thinking ability
with the individual unaware of reduced
performance.
• Memory impairment -short term memory is
lost early.
Symptoms of hypoxia
• Sensory loss- vision, especially for color, is affected
early, and then touch, orientation, and hearing are
impairment.
• Impairment of consciousness- as hypoxia progresses
the individual’s level of consciousness drops until he
becomes confused, then semiconscious, and
unconscious. Unless he is rescued he will die and at
high altitude death can occur within a few minutes.
How to prevent
• Reduce tolerance to altitude (descends)
• By enriching the inspired air with oxygen from
an appropriate oxygen system (Oxygen Tank
& Mask)
• By maintaining a comfortable, safe cabin
pressure altitude (Cabin Pressurization)