HPL

attributes to 70% accidents

predisposition: personality, inexperience, life stress

enabling factors: ergonomics, training/ briefing, administration

immediate causes: acute stress, cognitive failure, distraction, false hypothesis, disorientation, visual illusion

liveware: interactions, crew, ATC

software: computers, charts, checklists, manuals

hardware: mechanical environment around pilot

environment: hypoxia, heat & cold, radiation, toxic substances and weather 

two ways to treat safety culture

a) something an organisation is (beliefs & attitudes)

b) something an organisation has (structures, practise)

the nature of relations between subordinates and superiors

how often subordinated are afraid to express disagreement

closed culture: communication is poor to non-existent

the ICAO publishes standards and recommended practises (SARPS) designed to promote a common approach to aviation safety

each layer of cheese represents one layer of defence

holes and gaps are created by 

a) active failure: errors and violations of those at the human-system interface 

b) latent conditions: failure of designers, builders, managers and maintenance

- an informed culture

- a reporting culture

- a learning culture

- a just culture

- a flexible culture 

1. safety policy and objective

2. safety risk management

3. safety assurance

4. safety promotion

circulatory

repiratory 

nervous

endocrine

digestive

integumentary

immune

excretory 

reproductive

major organs are contained inside body cavities

maintaining constant internal environment 

• core temp (36.9)
• blood glucose
• oxygen
• blood pressure
• ion concentration
• ph (CO2)

CENTRAL NERVOUS SYSTEM

brain, spinal chord

PERIPHERAL NERVOUS SYSTEM

somatic (involuntary) nervous system

automatic nervous sustem
- sympathetic nervous system
- parasympathetic nervous system

motor neurons: carry signals to part of the body to initiate actions

sensory neurons: carry signals from sense organs of the body to the brain

neurons transmit signals as a series of electrical pulses, known as action potentials

- electrical current generated by charged potassium and charged sodium atoms across the cell membrane

- depolarises along the membrance- in quicker jumps with myelin sheath

sodium potassium are positively charged ions, 

this system is indefinitely self sustaining 

a response to stimuli is coordinated by the CNS

the sensory threshold is the amount of stimulation needed to initiate a nerve impulse in a sense organ

missing sensory info can result in a loss of situational awareness

an automated response that prevents the body from damage/harm

can occur with almost no CNS processing

e.g. tendon tap test

adaption:

decreased response from sense organs to repeated stimulation over time

habituation:

decreased response by CNS to repeated stimulation over time

(potentially dangerous as you may disregard warnings is repeatedly sounded)

Mechanoreceptors:

inside tendons and transmit information. a sensory receptor that reponds to mechnical pressure or distortion

Proprioceptors:

sensors that provide information about joint angle, muscle length, and muscle tension. gives information about the position of the limb in space

glands secrete hormones into the blood

cells with receptors for the specific hormone respond to the message

adrenaline = fast

growth hormone= slow

transport
cytoplasm, blood, tissue, lymphatic fluids

temperature control
high heat allows water to act as a buffer- essential in endothermic organisms that need a constant body temp to optimise enzyme action

hydrogen bonding
requires a lot of energy for water to evaporate- utilised in cooling mechanisms e.g. sweating

double circulatory system
blood passes through heart twice in every complete journey around the circulatory system

the pulmonary circuit 
low pressure, deoxygenated blood from the heart to the lungs 

the systemic circuit
high pressure, oxygenated blood from the heart to the rest of the body

delicate blood vessels transporting blood, nutrients and oxygen to cells (smallest blood vessels)

e.g. from artery to vein 

is regulated by the medula oblongata (hind brain)

nerve impulses arrive at the sinoatrial node (SAN) located in the right atrium 

nerves and hormones affect HR

Sympathetic nerves increase HR
Parasympathetic nerves decrease HR

Arteries are thicker as higher pressure

veins are thinner and have valves to stop backflow- situated deep in muscles (deep vein thrombosis)

measurement of the pressure generated by the contraction and relaxation of the heart

systolic pressure - heart contraction

diastolic pressure - radial pressure when heart relaxes 

resting HR= 72bpm

blood pressure= 120/80 mmHg

CARIAC OUTPUT= HR X STROKE VOLUME

(5litre a min at rest)

plasma
liquid carried cells of blood

red
contains haemoglobin to carry oxygen to the cells and tissues

white
produce antibodies to fight bacteria

platelets
assist in the blood clotting process

oxygen is carried by the protein haemoglobin in red blood cells

oxygen+haemoglobin= oxyhaemoglobin

red blood cells are made in the bone marrow, but also liver and spleen. live for about 120 days

combined with water= carbonic acid 

dissolved in blood plasma

the brain controls breathing be measuring blood CO2 level- determined by the amount of carbonic acid in the blood 

reduction in haemoglobin available due to reduced number of red blood cells or haemoglobin in the red blood cells

product of incomplete combustion

haemoglobin has 210-250 times greater affirmity for CO than oxygen

odourless and colourless 

treatment

• turn off cabin hea

Hypotension: low blood pressure

shock, massive bleeding, disorders of endocrine system

Hypertension: high blood pressure

heart is under stress

narrowing of the coronary arteries due to a build up of fatty deposits (atheroma)

consequences:

angina, Myocardial infraction (heart attack)

cells obtain energy through ennzyme catalysed oxidation of glucose. 

the respiratory ststem extracts oxygen from the atmosphere for cellular respiration (internal respiration)

Breathing is reffered to as external respiration function

sites of gas exchange between blood and atmosphere

oxygen and co2 diffuse into and out of the blood

oxygen= into the blood

co2= out of the blood

thin walls surrounded by capillaries 

chemoreceptors detect the pH level (CO2) in the blood baroreceptors detect blood presssure, both influencing ventilation rate

diaphragm contracts: volume of pleural cavitiy increases. air forced into lungs and lungs expand

diaphragm relaxes: volime of pleural cavity reduces. air forced out lungs and lungs contract

total lung capacity= 6 litres

residual volume= 1.5 litres

tidal volume= 500ml

normal respiration= 12-20(16) breaths/minute

Mean sea level temp: 15 degrees c

MSL atmosphere pressure: 1013.2 hPa

Lapse Rate: 1.98 degrees per 1000ft

Tropopause Height: 36090

Tropopause Temp: -56.5 degrees

MSL Air Density: 1.225kg/m^3

MSL gravity: 9.871ms^-2

oxygen 21%

nitrogen 78%

argon .93%

co2 .03%

rare gases .04%

water vapour 3%

VOLUME X PRESSURE = CONSTANT 

VOLUME IS PROPORTIONAL TO TEMPERATURE 

THE PRESSURE OF A MIXTURE OF GASES IS THE SUM OF THE PARTIAL PRESSURES OF ITS CONSTITUENTS

GASES WILL DIFFUSE

RATE OF DIFFUSION DEPENDS ON 

CONCENTRATION GRADIENT

DISTANCE

TEMPERATURE

PRESSURE

THE AMOUNT OF GAS DISSOLVED IN A LIQUID IS PROPORTIONAL TO THE PRESSURE OF THAT GAS OVER THE LIQUID 

as pressure dounbes, solubility doubles 

P1 V1 T2 = P2 V2 T1

P1 V1

   T1

P2 V2

   T2

Haemoglobin combines reversibility with oxygen to form

oxyhaemoglobin

as altitude increases, oxygen absorption in blood decreases

the partial pressure of oxygen in lungs is lower than atmospheric, due to 100% water vapour and increased carbon dioxide

water vapour in lungs effect increases with altitude

34000ft lung pressure is 140mmHg

minemum acceptable partial pressure of oxygen is 55mmHg

9000ft: 1/4 oxygen is below 

18000ft: 1/2 is below

34000ft: 3/4 is below 

at 10,000ft, 3/4 pressure of MSL (700hPa), 70% usable

at 18,000ft, 1/2 pressure of MSL (530hPa), 52% usable

at 36000ft, 1/4 pressure of MSL (250hPa), 25% usable

Sea level: 97%
10,000ft: 87%
20,000ft: 65%

10,000ft.             --- air only
10,000-33,700ft  --- oxygen/air mixture
33,700ft-40,000ft---100% oxygen
40,000ft+.            --- 100% oxygen under pressure

pressure drops 6000-8000ft at altitude

(cabin pressure)

at 8000ft cabin altitude the pressure differential across the fuselage is about 465mmHg

during cabin depressurisation the cabin may rise to above the pressure altitude due to the venturi effect of air passing over the fuselage

up to 5000ft difference

Hypoxic Hypoxia
reduces the level of oxygen. disease, asthma or lung infection

Anaemic
lack of haemoglobin. traumatic injury, blood disorders 

Stagnant
low blood flow. heart disease or vasoconstriction

Histotoxic 
poisoning cabon monoxide

• visual sensory loss (night vision at 5000ft)
• tunnel vision
• impairment of consciousness
• cyanosis
• formication
• unconsciousness
• death
• memory impairment approx 12000ft

indifferent - 5-10kft
dark adaption affected

compensatory- 10-15kft
automatic responses provide proteftion- attemp at maintining homeostasis 

disturbence - 15-20kft
physiological compensatory mechanisms no longer capable of providing for adequate oxygenation of tissues

critical - 20-23kft
incapacitation with loss of consciousness with little to no warning

20,000ft.        30 mins

25,000ft.        2-3 mins

30,000ft.        1-2 mins

35,000ft.        30-90 seconds

40,000ft.        15-20 seconds

reduced amount of cabon dioxide in the blood

improved by foced breathing 

paper bag