Basics of Flight Physiology Flashcards
State the units used when measuring the total and partial pressure in atmosphere
Pascals or N/m2
State proportions and pressures of O2, N and other in atmosphere
78%,21%,1%
Partial pressures are in same proportion as the volumes. Total pressure is 760 mm Hg, so
Nitrogen 0.78760=592.9 mm Hg
Oxygen 0.21760=160 mmHg
What happens to proportions of gases throughout the atmosphere
They are constant
What is Boyles Law?
P and V are inversely proportional
Barotrauma
Charles’s Law
V is proportional to T
Gay-Lussac
T proportional to P
What is the combined gas law/ general gas law
PV/T = const
Daltons
Sum of partial pressures in mixture is equal to total pressure
This causes Hypoxia
Henry’s Law
Amount of gas dissolved in liquid is proportional to its partial pressure
This is to do with Decompression sickness
What are ICAO parameters?
What is standard temperature lapse rate?
T = +15degC
P =1013.25 hPa or 760 mmHg or 29.92 inHg
RHO = 1.225kg/m3
Lapse rate is -1.98degC per 1000ft
State altitudes that the pressure will be at percentages of MSL pressure
75% - 9000ft
50% - 18000ft
25% - 34000ft
State effects of increasing altitude on overall pressure and partial pressures?
Pressures will decrease but partial pressure ratios will remain constant
Ficks law
Mathematically shows diffusion rates
Explain differences in gas expansion between alveolar and ambient air when climbing
More CO2 and water vapour in lungs than outside.
Air is constantly saturated at 37degC
Lung air pressure is always reduced by 47mmHg in lungs
So at MSL air pressure in lungs is 760mmHg-47mmHg=713mmHg
The effect of this constant reduction becomes disproportionally large at higher altitudes.
The proportions of others gases must fall. At 34000ft, oxygen is 13.7%
What conditions do humans need to survive at given altitudes?
Up to 10000ft - nothing
to 33700 ft - 02 + air mask keeps body at MSL
up to 40000ft - 100% oxygen in mask keeps body at 10000ft
above - pressurised oxygen
What is the importance of partial pressure
Lungs hold less % of oxygen at altitude due to partial pressure of water vapour, and decompression sickness happens due to dissolving of Nitrogen
List the main components of the respiratory system and their function
Nose - warms air
Trachea - brings air to lungs
Bronchi - splits into two lungs
bronchioles - sub-branches
Alveoli - surrounded by capillaires. diffuse o2 into blood
Diaphram - muscles that control breathing
inter-costal muscles - does heavy breathing
What are the different volumes of air in the lungs.
Tidal volume - Normal breath - 500ml
Inspiratory res volume - additional to fill lungs - 3100ml
Expiratory res volume - air that can be forcibly expired - 1200ml
residual vol - what is left 1200ml
Max air that can fill lungs = sum of all=6000ml
Vital capacity = Total that can be expired = 6000-1200 = 4800ml = 80% of total
Inspiratory capacity = max that can be inspired = 3600ml
What is the normal respiratory rate?
About 12-20/min
How are oxygen and carbon dioxide transported around the body?
What effect do they have on acidity
Oxyhaemoglobin and Co2 in blood.
High -> low pressure across alveoli
More oxygen in blood - more alkaline
More CO2 in blood - more acid
Heavy breathing for no reason = more oxygen so more alkaline
Explain the role of carbon dioxide in control and regulation of respiration
Blood is very efficient at holding onto oxygen, so its nearly always at 98%.
Carbon dioxide goes up and down so this is measures and breaths taken accordingly
How is oxygen transferred to the cells?
Through tiny capillaries
What is external and internal respiration
External is in lungs, oxygen and CO2 transfer
Internal is O2 and Glucose at the tissues
02 and glucose emtabolised to form fuesl for the muscles
Waste is carbon dioxide and water
These combine to form carbonic acid. This controls rate of breathing.
Waste water goes through sweat, kidneys or lungs
List the different senses
Touch taste smell hearing sight
State the multi-sensory nature of the human perception
Use all the sense together
Name the main parts of the central nervous system
brain, spinal cord
State basic functions of central nervous system
Most information processing Voluntary movements Receiving info from senses thinking memory emotion
Lower functions such as breathing and basic motor functions such as posture are closely associated with the brain stem
State basic functions of peripheral nervous system
Somatic -
Body movement and sensing external stimuli
Autonomic -
Unconscious things like blood vessels and control of internal organs
Has sensory and motor nerves
Discuss broadly how info is processed by nervous system and the role of reflexes
Senses by sensory neurons as part of peripheral system. These go to central nervous system and an action is called upon. This is then passed to motor neurons if needed.
Sometimes there is a direct link via spinal cord for a reflex action
Discuss electro-chemical nature of nerve impulse
One cell is a neuron. Has a cell body and an axon.
Signal travels length of axon as electrical wave. Is a chemical-electrical process. Called action-potential.
This goes at 0.5m/sec
Long motor neurons need faster method. Small breaks in the axon allow the signal to jump between the gaps. This is much faster. 100m/sec
Define sensory threshold
Below this the neuron won’t fire. For 5us after this the neuron requires much bigger stimuli to fire. This is habituation.
Define habituation and implication for flight safety
Decrease in physiological response as result of repeated stimuli.
Flight safety - don’t process things you should.
What is the gap between neurons called?
Synapse
What do the proprioceptors and mechanoreceptors do?
Proprioceptors detect and relay very precise information about the length of extension of each muscle.
Mechanoreceptors transmit very precise information about the amount of tension in a muscle
What do subcutenous receptors do?
They detect pressure. They are under the skin.
What is the endocrine system?
Slower means of communication. But can reach more cells.
Uses hormones in the blood, detected by receptor cells.
This is neural hormonal.
Not remotely voluntary. It plays a big role in homeostasis.
Examples. Insulin and adrenaline
Describe action potential
Uses sodium and potassium. PD builds up causes current to flow
Define humidity and relative humidity
What volume of water vapour per unit volume of air?
Relative is the proportion of water in the air compared with what could be held for a given temperature.
Hypoxia - two types and explain
Hypoxic hypoxia - not enough oxygen in system.
Caused by altitude, infection of lungs or airways, astham, drugs
Anaemic hypoxia - Caused by lack of red blood cells or inability for blood to carry oxygen. Can be from blood disorders or blood donations
Hypoxia is an example of Dalton’s Law - partial pressures
What are symptoms of hypoxia?
Initial - Stomach pain as gas expands, tingling sensation in hands and feet Cyanosis - blue lips and feet Increased rate of breathing Euphoria - happy/calm Ear discomfort
After symptoms - Impaired vision lack of motor skills drowsy slurred memory loss difficulty concentration
State why living tissues need oxygen
To combine with glucose to release energy
How high can healthy people compensate for lack of oxygen?
Up to 10000 - 12000 ft
How are altitudes broken down into how we deal with o2?
Indifferent 10kft Blood 02 is 95-90%
Compensatory 10-15kft 90-80%
Disturbance 15-20kft 80-70%
Critical 20-23kft 70-60%
What is time of useful conciousness?
Time available to fix your situation!
Times on wall
What happens above 10000 for hypoxia?
Indifferent up to 10000
10-15 - Compensatory stage, bosy adapts, may feel tired, may be difficult to do simple tasks
+15 Disturbance Visual, poor judgement
+20 Death
Factors affecting severity of hypoxia?
Smoking reduces TUC times by half
Define hyperventilation
Breathing faster than necessary, too much oxygen. Too alkaline.
Alkaline does damage. Brain slows blood flow to avoid damage.
Causes of hyperventilation
Factors that make it worse
Treatment
Voluntary
Stress/anxienty
strokes/brain injuries
Reduced air pressure respiratory disorders cardiovascular disease g-force heat
May be physiological or psycological
Bag breathing
Symptoms of hyperventilation
DIzzy Tingling Nausea Blurred Vision Muscle Spasms Loss of consiousness
Not dissimilar from Hypoxia
Bad question - below 10000ft, Hyperventilation
above - Hypoxia
Otherwise always treat for hypoxia
What is decompression
To do with Henry’s Law - amount dissolved is ppl to pressure
High Pressure to low pressure, Nitrogen is released into bubbles known as embolisms.
These get trapped in pinch points such as joints or organs, causing similar damage to a blood clot.
State altitudes to do with compression
To 14000 feet - no effec
Above 18000 - affect if prolonged
Above 25000 - affect is worsened
What are the 3 types of decompression sickness?
Bends - joints
Creeps - skin
Chokes - Large embolism in the heart. Chest discomfort them cough
Staggers - Brain
State diving limits with decompression sickness
Not fly within 12 hours of dive less than 30ft
Not fly within 24 hours of dive less more than 30ft
No risk with snorkelling
Treatments of decompression sickness
Always increase ambient pressure. So descend or use hypobaric chamber.
Need specialist medical attention for a long while afterwards
Can be limited with pre-oxygenation.
Name parts of circulatory system
Heart
Arteries
Veins
Capillaries
What are normal pulse, normal stroke rate and normal cardiac output
70 ml/ stroke * 72 BPM = 5.04L
Name four chambers of the heart and describe their function
Ventricles and Atria (Atrium of a building)
Left - Pumps to body
Right - pumps to heart
Atria stores it ready to go into ventricle
Ventricle does big push out of heart.
Stroke vol is the capacity of left ventricle
Describe arteries, veins, capillaries
Arteries - HP. thick
Veins - Thinner, has valves, deoxygenated blood
Capillaries - One cell thick
Pulmonary vein and artery are named the other way round
What do coronary arteries/veins do?
Supply blood to the heart muscle
Describe the main constituents of blood?
Red blood cells - carry oxygen
White blood cells - infection
Platelets - Coagulate blood/clotting
Plasma - transparent/yellow fluid. Has no cells. Just a liquid
Carbonic acid - Regulate breathing and pulse
What is the affect of altitude on haemoglobin - oxyen saturation
Not sure yet
List factors that determine pulse rate
70-75 BPM
Controlled by autonomic or vegetative nervous system
ANS monitors - carbonic acid glucose adrenaline exercise digestive temp up BPM up increases with age blodd pressure down rate up caffeine woman high than man
