Scuba Diving Physiology
- we have 2 system in our body:
cardiovascular system and respiratory system
Cardiovascular system:
- heart has 2 functions:
- pump rich blood( O2) to the tissues via
arteries, and pump poor blood (CO2) from the tissues via veins
- pump poor blood (CO2) to the lungs via
arteries and pump rich blood (O2) to the heart
the O2 and CO2 is
exchange via Capillaries to and from the tissues
- if we have too much CO2 it is called Hypercapnia
- if we have not enough O2 it is called
Hypoxia
- if we have too much O2 it is called
Hyperoxia or O2 toxicity
- the heart beats approx 60 to 80 times per
minutes and pump 5lt of blood per minutes
the O2 and CO2 is transported to and form the tissues via the red blood
cells
respiratory system
- the lungs is where gas exchange occur.
1st the air enter the trachea
then the bronchioles and then the alveoli.
The alveoli are cover by capillaries and it is where the gas exchange
- lungs capacity: (around 6.8lt of air)
- total lung capacity – from total collapse
to full inflation
- vital capacity – total amount of air
inhaled after maximal expiration
- residual volume – the amount of air left
in the lungs after maximal expiration
- tidal volume – the volume of air who is
exchanged during inhalation and exhalation
we breath around 12-20x per minute
we need to breath to decrese the CO2 level in the blood not because we
don’t have enough O2
because the air we breath at depth is denser, it is more difficult to
breath. To compensate, you need to breath more slowly
the response to stress from our body is to breath shallower.
By doing that, we don’t exchange enough new air from the regulator and
by breathing the same air again and again, our body tells our brain that the
level of CO2 is to high and we need to breath.
The best way to stop this pattern ( feeling that we don’t have enough
air), breath deeply until you feel better. Otherwise panic occurs.
TEMPERATURE
We loose temperature 25X
faster in the water than in the air
The most affected is by conduction
The least affected is by radiation
TOO COLD
·
Mild
Hpyothemia: (body react) not dangerous if handle correctly- don’t need hospital
1.
when the
body core temperature (inside the body) is too low (less than 37)
2.
symptoms :
shivering, difficulty to move the extremities
3.
best thing
to do : stop the dive and dry off, drink hot fluids
1.
Advanced
hypothermia: (body stop reacting) dangerous- need hospital
1.
fail to
handle mild hypothermia
2.
symptoms :
no shivering, feeling hot again, blackout, death
3.
best thing
to do: stop the dive, dry off, treat for shock while transporting to hospital
TOO HOT
·
Heat
exhaustion: (body react) not dangerous if handle correctly – don’t need
hospital
1.
when the
core body temperature is to hot
2.
symptoms :
heavy perspiration (sweat) , cool skin, normal color, nausea
1.
best thing
to do: shower, drink, jump in water, open the wetsuit, go away from the sun
·
Heat
stroke : (body stop reacting) dangerous – need hospital
1.
fail to
handle heat exhaustion
2.
symptoms :
skin is hot, red, and the sweat stop, blackout , death
3.
best thing
to do : protect from heat, wet towels, treat for shock while transporting to
hospital
SQUEEZE (BAROTROMA)
A squeeze occur when the pressure outside and air space is more than the
pressure inside
Don’t attempt to forcefully equalization, you can break the round window
in the middle ear
If you don’t equalize you ears, you can break the eardrum who produce
vertigo because cold water enter in the middle ear
It can happen in:
1.
THE EARS -
equalize all the way
2.
THE MASK –
add air by blowing with the nose
3.
THE
DRYSUIT – add air on the way down
4.
THE LUNGS
– never empty your lungs on descent
5.
THE
SINUSES – equalize all the way
REVERSE BLOCK
A reverse block can
happen when the pressure inside an air space is more than the pressure outside
and the air cannot escape
It can happen in:
1.
THE EARS –
never take decongestion pills before diving
2.
THE LUNGS
– holding the breath on ascent
3.
THE
SINUSES - never take decongestion pills before diving
If it happen, go down a little a ascent very slowly and
ONLY DIVE IF YOUR SINIUSES ARE HEALTY
SINUSES:
We have 4 pairs of
sinuses:
1.
frontal
sinuses – above the eyes
2.
maxillary
sinuses – below the eyes
3.
ethmoidal
sinises – base of the nose
4.
spenoidal
sinuses – deep inside the skull
EARS : the ears are divided in 3 parts:
1.
the outer
ear (the part that we see outside until the eardrum
2.
the middle
ear (the part who is the most affected by pressure)
3.
the inner
ear (who is in the skull and is not affected by pressure
when we equalize, we push air from the sinuses into the Eustachian tube
and add air to the middle ear.
DECOMPRESSION ILLNESS
(DCI)
Is divide in 2 groups :
1.
Decompression
sickness
2.
lungs
overexpansion
Decompression sickness:
Nitrogen goes out of
solution
Causes: - too fast up
(max 9m / minute)
-
stay too
long (ndl limite) non decompression limit
-
stay too
deep (ndl limite)
predisposing factors:
- dehydratation (water is taken
from the body to rehydrate the dry air from the cylinder)
-
alcool
-
obesity
(slow tissues release N2 slower)
-
injury
-
smoking
(CO2 bonds 200x better with red blood cells than O2)
-
lack of
sleep
-
illness (
the body focuses on the part to repair and send O2 and N2 in that place 1st)
-
poor
fitting equipment
-
certain
drug
-
decompression
dive
symptoms: - joint pain
- tingling
- Numbness
- irritation
- swelling
- extreme fatigue
- weakness
- paralysis (when the bubbles are around the spinal cord)
- black out
- convulsion (when the bubbles are in the brain)
- nausea
- vomiting
- shortness of breath
- shock
- death
1st aid: - 100% o2 for 30’
- treat for shock
- lay down in recovery position
- transport to hospital
- call DAN (diver alert network)
LUNGS OVEREXPANTION
4 DIFFERENT KINDS:
1.
Air
embolism
2.
mediastinal
emphysema
3.
subcutaneous
emphysema
4.
pneumothorax
AIR EMBOLISM: air inside the bloodstream
MEDIASTINAL EMPHYSEMA : air in the middle of the chest
SUBCUTANEOUS EMPHYSEMA : air
under the skin
PNEUMOTHORAX : collapse lungs
causes: holding the breath on ascent (most dangerous between 10m and the
surface) 1.0m DIFFERENCE CAN CAUSE LUNGS OVEREXPANTION
symptoms : SAME AS THE DCS
- joint pain
- tingling
- Numbness
- irritation
- swelling
- extreme fatigue
- weakness
- paralysis
- black out
- convulsion
- nausea
- vomiting
- shortness of breath
- shock
- death
1st aid: - 100% o2 for 30’
- treat for shock
- lay down in recovery position
- transport to hospital
- call DAN (diver alert network)
NITROGEN NARCOSIS
Causes : high partial pressure of N2 (nitrogen) the Meyer-Overton theory
It can
happen as shallow as 24meters
Symptoms : like to be drunk :
- euphoria
- confusion
- foolish behaviors
- impaired coordination
- false sense of security
- fixation of idea
- visual hallucinations
- deterioration of reasoning
1st aid : ascent to
shallower depth
CONTAMINED AIR
Causes : Improper filling intake of
the compressor (Carbon monoxide, oil vapors)
Avoid: smell and taste the air
before diving, fill in a trusted diveshop
Symptoms: - headache
- red lips
- red finger nails
1st aid : - stop diving
- 100% O2
- Hospital if needed
OXYGEN TOXICITY
2 KINDS : CNS (central nervous
system or pulmonary)
CNS: due to high partial
pressure of O2 more then 1.4 ppO2
Symptoms:
- visual disturbances
- ear ringing
- muscle twitching
- vomiting
- convulsions
1st aid : stop the dive
PULMONARY O2 TOXICITY : too long exposure to high ppO2
Symptoms :
-
burning
sensations in the lungs
1st aid : stop diving until it’s gone
GASES:
O2 : OXYGEN
O2 is about 20.9% of the air that we breath
O2 is transported by the red blood cells, and is absorb via the lungs
(alveoli) to the circulatory system by the capillaries
O2 is good for us
if the partial pressure don’t pass 1.4ppo2
Minimum ppo2 to
stay conscious is 0.10 ppo2
We use 100% of O2
to any diving related problems. Its provide the tissues with more O2 than normal air.
N2 : NITROGEN
N2 is about 78 % of the air that we breath.
N2 is transported by the red blood cells and absorb by the tissues if we
dive because of the pressure differential.
Without diving, the N2 is not absorb by our tissue
N2 causes nitrogen narcosis when under high partial pressure
CO : CARBON MONOXIDE
CO
is produce by burning materials :
Cigarette à it takes 12 hours to clean the body from 1 cigarette
Gasoline à when petrol driven compressor is used to fill
cylinders, a small or big amount can be find inside the cylinder.
The intoxication produce light head, strong headache, excessive
hyperventilation , confusion and black out
It can be very dangerous to have even a small amount if it in the
cylinder while the air that we breath is denser than at the surface. Always be
sure that the filling station and filters are clean and changed as the
manufacturer recommends.
CO2: CARBON
DIOXYDE
CO2 is produce by the muscles who use the O2 to produce power. The waist
product is CO2. High level of CO2produces Hypercapnia (too much of CO2) and
tells the brain to breath.
A : ARGON
argon is present I air in a very small
quantity.
In diving it is used for dry suit inflation since it have about twice
the isolation capacity than air.
He : HELIUM
Helium is present in
air in a very small amount
In diving, it is use to
counter the effect of nitrogen narcosis is tech diving
Heliox is a mix of
helium and O2 with no N2
Trimix is a mix of
Helium, O2 and N2
Both of them are use in
tech diving
