Physiology Flashcards
What are cones in the eye used for?
Colour and acuity
What are rods in the eye used for?
Seeing at night/dusk.
Detecting light intensity
Peripheral vision
Why can’t we look directly at objects at night?
The fovel centratils only has cones, no rods
How do we look at items at night?
What do we do differently from day?
We use our prepherial vision, so need to look to the side.
How long does it take for eyes to adjust at night
Rods take 20-30 minutes to adapt
How long do cones take to adjust
Cones adapt in 6-8 minutes
What is the most important sense?
Vision
What senses motion?
For the body
Inner ear ( vestibular system )
What is the sclera?
It gives the eye its form. Outside the retina
What is the cornea?
The cornea is the transparent part of the sclera
What is the iris?
It controls the amount of light allowed into the eye
What is the lens?
The lens is used to focus the eye.
What are cones?
Cones detect colour
Cones provide visual acuity
Where are rods and cones concentrated?
Cones in the Macula.
Rods in on the edges
What is empty field myopia
Eyes will focus at default ( 3 to 4m )
Pilot will think they are looking outside, they only see the front of the plane.
What is the recommended scanning rate
No more than 10 degrees per second
How long is our reaction time when looking?
Time between seeing and doing something
About 1 1/2 seconds
What is perception?
Organisation, identification and interpretation of sensory information.
It has a lot of baises
What are the limitations of a mental model?
Founded on incomplete facts
Is flexible - both in a positive and negative way
Is limited compared to actual world
What is bottom up processing?
Sensory information going directly to the brain. No thinking required
What is top down processing?
Using top down to make sense of the world. E.g relative sizes of things to decide what is closer.
What decreases or increases the amount of attention needed?
Pre-existing knowledge - requires less attention
Talking - requires attention
What is working memory?
Short term memory.
Fills up quickly and easily wiped.
What is long term memory?
What is the main problem?
Important information is held here.
Problem is retrieval
What is the cause of motion sickness?
Slow unfamiliar movements
Mismatch of sensory inputs
What is the gas mix in the atmosphere ?
1% other
21% Oxygen
78% Nitrogen
Cause of air sickness ( and how address them )
Slow or slight movements you are unfamiliar with
To fix:
- look outside at a fixed point.
What is the rapid eye movement between fixed points called?
Nystagamus
What is partial pressure?
Pressure of a single gas in the atmosphere.
Action coping, cofniative coping, symptom directive coping
Action Coping - Taking action, for example talking to someone who is causing stress.
Cognitive coping - taking mental steps to avoid stress, based on perception. However, may not always be addressing the root cause ( for example suppression or avoidance )
Symptom Directive Coping - Using drugs or alcohol, excessive exercise. To ‘take your mind off it’
What is the decrease in temp as we increase altitude
Approximately 2 degrees c
Per 1000 feet
How does altitude increase affect our lungs the ability to absorb oxygen?
Results in a lower pressure of air, therefore lower partial pressure and lower water saturated partial pressure
**Sealevel
**
Air 760 mmHG
PO2 159
PAO2 103
**10,000 Ft
**
Air 523
PO2 109
PAO2 61
Difference between acute and chronic fatigue
Acute - normal and short term
Chronic - caused by prolonged stress. When it becomes serious enough it leads to emotional illness
Symptoms of Hypoxia
Fuzziness of the head or thick feeling
slow of thought and poor judgement
failing memory
clumsiness
Feeling of euphoria
Mental fixation on unimportant tasks
visual changes
quick breathing
extremities turn blue due to reduced O2
How does Carbon Dioxide posioning work?
It combines with haemgoblin to create carboxyhaemoglobin - which takes space for haemoglobin.
Treatments for Hyperventilation
Slow down breathing
Breathe into paper bag ( to build up CO2 levels )
100% oxygen ( when at altitude )
How do the Right / Left Heart flows work
Right Heart -> Lungs -> Left Heart -> Body -> Right Heart
What do veins and arteries do
Veins carry blood to the heart
Arteries carry blood away from the heart
( Thats why killers cut arteries )
What does the respitroy system do?
Provides O2 and removes COs
What does the cardiovascular system do?
Transports Blood and therefore Oxygen to organs.
What happens if outside pressure = body fluid pressure?
Blood will boil ( i.e in space without a spacesuit )
One unit of Alcohol is for:
Spirits
Beer
Wine
Spirits - 2.5cl ( 1 measure )
Beer - 28cl ( 1/2 pint )
Wine - 12cl (1 glass )
Describe how the Vestibule System works
Detects Linear Motion
Utricle - Horizontal
Saccule - Vertical
One is in each side of the head
Has gel like substances ( membrane and stones )
Cilla detect linear motion
Describe how the Semicircular canals work
3 tubes on each axis
Fluid called Endolypmh.
Stationary in base is the Ampulla
Ampulla has cilla to detect deformity
As the fluid moves, the Ampulla gets deformed and acceleration is detected.
Describe parts of the eye
Lens - clear
Sclera - gives shape
Corena - transparent part of the Sclera
Iris - for light control
Rods - light intensity
Cones - colour and acuity
Retina - lining - detects light
Optic Nerve - back to brain - blind spot
Which organ is least likely to affected by pressure changes?
Lungs ( due to their large size )
What is barotrauma?
Differences in pressure in cavities in the body.
E.g Ear.
The Valsalva manouver is used ( pitch nose ) for this case.
Avoid canned and presurised drinks before flying
What are the stages of G Force?
Grey Out
Black out (Red out if inverted )
G Loc
What are the layers of the atmosphere?
Thermosphere
Menosphere
Stratasphere
Tropopause
Troposphere
What types of body cavaties are affected by Pressure changes?
Both Closed and Open.
Large are less affected ( I.E we dont get lung pains… we get ear pain, teeth pain, joint pain, tummy pain first )
how long after diving can you fly?
If going above 8,000ft
Scuba - no decompression stops
12 Hours
Scuba - decompression stops
24 hours
Treatment if someone has been diving
100% Oxygen
Emergency Descent
Even 500ft could be fatal
Do not move joints to help
Describe the 3 rotation effects
Centrigual - sending us outwards
Centripedal - counter to centrifugal
Coriolis - caused by rotation of the earth ( we will seem to head left when flying north )
