Free diving

Question 1

What is the historial significance of free diving?

Answer 1

Used for hunting and gathering
Military
Sport

Question 2

Physiological challenges of apnea diving

Answer 2

Hypoxia and hypercapnia
Extreme hydrostatic pressure
Increased gas uptake and nitrogen saturation

Question 3

Body response to diving

Answer 3

Bradycardia
Spleen contraction
Elevated blood pressure
Vasoconstriction of peripheral vascular beds

Question 4

What is bradycardia?

Answer 4

Reduction in heart rate

Question 5

What happens to cerebral blood flow during static apnea?

Answer 5

Hypercapnia and hypoxia causes cerebral vasodilation (but important to manage intracranial pressure)

Question 6

The spleen is innervated by

Answer 6

The sympathetic and parasympathetic nervous system

Question 7

White pulp function in the spleen

Answer 7

Immunological

Question 8

Red pulp function in the spleen

Answer 8

Erythrocyte filter and reservoir

Question 9

Describe reduction in spleen volume

Answer 9

~20-40% reduction in spleen volume causes 3-9% increase in O2 carrying capacity of blood

Question 10

Length of time Mirounga Angustirostris spend at sea

Answer 10

9-10 months
80-90% of that is underwater
Average dive >400m deep

Question 11

Describe SaO2 levels in Mirounga

Answer 11

<80% for ~80% of their dive
~6.5 month/year <80%

Question 12

Describe SaO2 levels in Mirounga

Answer 12

<80% for ~80% of their dive
~6.5 month/year <80%

Question 12

Describe SaO2 levels in Mirounga

Answer 12

<80% for ~80% of their dive
~6.5 month/year <80%

Question 13

Physiological adaptations of Mirounga

Answer 13

High amounts of carbon monoxide protects against intermittent hypoxia

Question 14

Injury associated with deep dives

Answer 14

Lung squeeze

Question 15

Symptoms of lung squeeze

Answer 15

Tightness/irritation in chest, trachea or larynx
Hemopytsis (coughing up blood, or blood stained mucus)
Cough
Dyspnea

Question 16

Symptoms of lung squeeze

Answer 16

Tightness/irritation in chest, trachea or larynx
Hemopytsis (coughing up blood, or blood stained mucus)
Cough
Dyspnea

Question 17

Describe airway when diving

Answer 17

5 seconds to lower into water - normal airway
10 seconds while diving - narrowed airway
5 seconds to get back to top - closed airway

Question 18

Compare Bajau and Ama diver depth average

Answer 18

Ama - 7.5m (minimum 5, maximum 12m)
Bajau - 5m (minimum 5m, maximum 7m)

Question 19

Physiological features of Ama, Bajau and elite divers

Answer 19

Increased lung volumes
Aortic stiffness
Spleen volume
Spleen contraction
Underwater eyesight

Question 20

What we dont know about free-diving populations

Answer 20

Structural or functional changes to the heart
Vascular adaptation
Blood volume
Antioxidant activity

Question 21

Challenges to studying indigenous divers

Answer 21

Time (loss of trained adaptations)
Population decline (urbanization, commercialization, migration)
Hard accessibility

Question 22

Describe scuba diving

Answer 22

Self-contained underwater breathing apparatus that prolongs time underwater by using compressed gas

Question 23

What gases are used in scuba diving

Answer 23

Nitrox/air; O2 and N2
Heliox; O2 and He
Trimix; O2, He, N2

Question 24

Describe the deepest scuba dive

Answer 24

332m 9 gas tanks 12-minute descent 15-hour ascent

Question 25

What is nitrogen narcosis caused by

Answer 25

Breathing a high concentration of nitrogen that the gas functions as a mild anaesthetic

Question 26

Why does nitrogen cause a mild anaesthetic

Answer 26

Disruption of the ion transport channels or direct impact on receptors in the CNS

Question 27

Risk factors to nitrogen narcosis

Answer 27

Fatigue and exertion Hypothermia Age Hypercapnia Anxiety

Question 28

What is decompression sickness?

Answer 28

Happens during ascent, and its the release of gas in tissue. Severe outcomes related to CNS impacts.

Question 29

How is DCS prevented?

Answer 29

Dive time Depth Ascent rate Surface intervals

Question 30

What does DCS effect?

Answer 30

Cerebral system (nausea, dizziness, convulsions) Spinal cord (back pain, paraplegia) Cerebellar (ataxia, vertigo) Lungs Inner ear Joint Lymphatics Skin

Question 31

Risk factors for DCS

Answer 31

% body fat Older age Poor fitness Dehydration Pathologies Exertion Diving experience (rapid ascent, repetitive dives, short surface interval) Cold Airline travel

Question 32

Treatment for DCS

Answer 32

Get to a recompression chamber ASAP

Question 33

What is barotrauma?

Answer 33

Rise or fall in pressure of trapped gas causing damage to surrounding tissue

Question 34

Different types of barotrauma

Answer 34

Tympanic/inner ear Pulmonary Ocular Sinus

Question 35

Describe the 28 days spent in commercial saturation diving

Answer 35

Days 1-4 - compression (gradually avoid HPNS) Days 4-21 - work phase (bell winched down to dive site daily) Days 21-28 - decompression (very gradual to avoid DCS)

Question 36

High pressure neurological syndrome occurs at what depth

Answer 36

>200m, but can occur earlier

Question 37

High pressure neurological syndrome is characterized by

Answer 37

Helium gas Tremor Memory/cognitive impairments Epilepsy-like episodes CNS hypersensitivity

Question 38

High pressure neurological syndrome increases with

Answer 38

Increasing depth (rate of compression and individual susceptibility)