1. BSAC Ocean Diver Training
The Body and Effects of Diving

2. The Body & Effects of Diving
Aims
The Body Mechanisms
Metabolism
Respiration
Circulation
How diving affects them

3. The Body Mechanisms = Metabolism - The process of life Body cells
Energy
Food +
Oxygen =
Body cells
Food + Oxygen = Energy
Body
Cells
Waste products removal
Water +
Carbon Dioxide
Two interconnected systems
Respiratory system
Circulatory system

4. Respiration - The Lungs
The Mechanics of Breathing
Vital Capacity 4.5 litre
Lung Capacity
Tidal Volume litre
Residual
Volume litre
Inhale
21% Oxygen
79% Nitrogen
Exhale
17% Oxygen
4% Carbon Dioxide
79% Nitrogen

5. The Lungs - Gas Exchange
The Gas Exchange
The Alveoli
Oxygen =O2 O2
Carbon Dioxide =CO2
CO2
Air In/Out
Blood To Body via Heart
Blood From Body via Heart

6. Circulation - Heart and Blood
Circulation - Heart & Blood
Lungs
OXYGEN
Collected in lungs
Travels to heart
Travels from heart
Delivered to body cells
CARBON DIOXIDE
Collected from body cells
Travels to the heart
Cells
Travels to lungs
STIMULUS TO BREATHE
The need to expel carbon dioxide

7. Breath Hold Diving and Hyperventilation
Normal Dive O2
CO2
Start Dive
O2 Level to support Consciousness
CO2 Level for Stimulus to breathe
During Dive
End Dive
Dive with Hyperventilation O2
CO2
Start Dive
O2 Level to support Consciousness
CO2 Level for Stimulus to breathe
During Dive
Diver Unconscious

8. Air Spaces affected by Diving
SINUSES
MIDDLE EAR
Lungs
AIRWAYS
GUT
GUT

9. The Ear Effects of Diving Ear Drum Middle Ear Eustachian Tube
Inner Ear
Outer Ear
Ear Drum
Eustachian Tube
Effects of Diving
Sound travels faster underwater - direction difficult to identify
Air space - Ear Drum, Middle Ear, Eustachian Tube

10. Effects of Diving on The Ear
Normal on descent
Increased pressure and blockage on descent
Reverse Ear
Never ‘force’ equalisation
Ascend to shallow depth (pressure)
DO NOT DIVE WITH A COLD

11. The Sinuses - Effects of Diving
Before Dive
Mucus membrane
Air
Block
Membrane swelling
Membrane rupture
Air
Blood
During Dive
Not serious but results in
Blood in the mask
Sinus pain
Do not dive with a cold
Bleeding into nasal passage
Air
Teeth
Dental checkups

12. Body Temperature Control
Body heat generated by metabolism
Core body temperature maintained at 37oC
Cooler surroundings = heat loss
Most through head and face
Chest front and under armpits
Peripheral blood supply restricted
Hands, feet, nose, ears
Less blood flow = less heat loss
Shivering
Hypothermia
37oC

13. Heat Loss and Diving Heat Loss In Water 25x faster than air
400 C
Normal body
temperature
370 C
300 C
No suit
required
Cold water increases rate of heat loss
Insulation consideration for divers
Wetsuit / Drysuit
required
200 C
Drysuit
required
100 C
End the dive if getting cold
00 C

14. Insulation Wet & Semi Dry Suits
Comfortable close fit
One or two piece
Hood and gloves
Boots if strap fins
Body
Water
Wet Suit
Maintenance
Wash in fresh water

15. Insulation - Dry Suits Maintenance - Wash in fresh water
Neoprene Dry Suit
Membrane Dry Suit
Body
Water
Under Suit
Air
Body
Air
Water
Comfortable fit
Strap fins
Hood & gloves
Maintenance - Wash in fresh water

16. Buoyancy = = + Object submerged Density
Archimedes principle When an object floats in water it displaces a weight of water equal to its own weight
Object submerged
Water displaced =
Force (Upthrust) = water displaced
Density
Object sinks
Weighs more than upthrust (Heavier than water displaced) = +
Air
Object floats
Weighs less than upthrust (Lighter than water displaced)

17. Buoyancy and Divers Positive Buoyancy Neutral Buoyancy
Too light
Physically tiring
Uncontrolled upward movement
Neutral Buoyancy
Positive
Weightless state
Reduces physical effort
Negative Buoyancy
Neutral
Too heavy
Self or marine life damage
Risk of going too deep
Negative

18. Buoyancy & Diving Descent During dive Ascent
Combined effect of diver’s body, suit and SCUBA - positive buoyancy
May need additional weight
During dive
Fine tuning with lungs
Ascent
Air will expand
Controlled dumping of air equalises diver’s buoyancy
Buoyancy check - correct weighting

19. Exhaustion & Diving An inability to meet physical demands
Buoyancy problems
Getting cold underwater
Working hard underwater
Mental tiredness or anxiety
Lack of general fitness
The night before!
Always ask the question : Are you fit to go diving?

20. Summary The Body Mechanisms How diving affects them
Metabolism
Respiration
Circulation
How diving affects them
Ensure fitness to dive