BSAC Ocean Diver Training The Body and Effects of Diving

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

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

Respiration - The Lungs The Mechanics of Breathing Vital Capacity 4.5 litre Lung Capacity Tidal Volume 0.5 litre Residual Volume 1.5 litre Inhale 21% Oxygen 79% Nitrogen Exhale 17% Oxygen 4% Carbon Dioxide 79% Nitrogen

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

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

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

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

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

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

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

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

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

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

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

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)

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

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

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?

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