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BIOL2018:Adaptive Physiology > Diving Physiology > Flashcards

Diving Physiology Flashcards

1
Q

Humans with diving adaptations

A

Ama divers in Japan (reduced expiration flow), Pearl divers of the Tuamoto Archipelago and Extreme divers.

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2
Q

Adverse effects of diving in humans

A

The bends, oxygen toxicity, narcotic effect of gases, oxygen supply and effects of high pressure.

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3
Q

The Bends

A

Occurs when humans return to surface after prolonged time at depth of 20+ meters, with higher severity in greater depths and time.

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4
Q

What causes the bends?

A

Bubbles of nitrogen forming in the blood.

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5
Q

Symptoms of the bends

A

Joint and muscle pain, neurological problems, headaches and strokes.

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6
Q

Boyle’s Law

A

Volume of a sample of gas is inversely proportional to the pressure applied to the gas if temperature is constant

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7
Q

What happens every 10m of depth?

A

Subjected to 1 extra atmosphere of pressure.

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8
Q

ppO2 at sea level

A

0.2 atm.

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9
Q

ppO2 at 10m (2 atm)

A

0.4 atm.

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10
Q

ppO2 at 40m (5 atm)

A

1.0 atm.

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11
Q

What does higher pressure at depth cause?

A

More nitrogen dissolves in blood/

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12
Q

How can the bends be avoided?

A

Rapid descent and a short time at depth, to prevent bubble formation diver must ascend carefully with stops at various depths with a quick initial ascent to half depth and then slower after.

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13
Q

Why must you exhale?

A

To prevent lung rupture.

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14
Q

How are the bends overcome?

A

Staying still as bubble formation is increased by muscle movement, can only be treated by increasing pressure so bubbles redissolve.

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15
Q

How can the diver increase pressure?

A

Back down to the depths or enter a decompression chamber.

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16
Q

Can helium be used for diving?

A

It is safer than nitrogen and less likely to form bubbles but it is expensive with evidence of helium narcosis.

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17
Q

Heliox

A

Used below 30 metres to 200-250m, has around 10% oxygen.

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18
Q

What happens at 150m?

A

High pressure nervous syndrome or the shakes with dizziness, nausea and drowsiness.

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19
Q

Trimix

A

Used below 250m, uses oxygen, helium and nitrogen up to 450m depth.

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20
Q

Pure oxygen at 1atm

A

Harmful for most animals, after 24 hours distress and increased lung irritation with rats dying after a few days due to irritation.

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21
Q

Pure oxygen at 2atm

A

Nervous symptoms develop before lung irritation, causes convulsions and movement reduces tolerance.

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22
Q

Pure oxygen at 3atm

A

Tolerated for a few hours.

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23
Q

Pure oxygen at 7atm

A

Convulsions after 5 minutes.

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24
Q

Problems with oxygen for diving

A

Seizures and coma, nausea and disorientation, pulmonary oedema and issues with reactive oxygen species

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25
Q

Nitrogen at 36 metres for 1 hour

A

Nitrogen narcosis.

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26
Q

Nitrogen at 45-60 metres for 1 hour

A

Drowsiness.

27
Q

Nitrogen at 75+ metres for 1 hour

A

Akin to alcohol overexposure, the raptures of the depths.

28
Q

Nitrogen at 90 metres for 1 hour

A

Unconsciousness and death.

29
Q

Safe limit for compressed air

A

30 metres, can become 50 metres with repeated exposure.

30
Q

Methods to manage oxygen supply in diving air-breathing animals

A

Increase oxygen storage, decrease oxygen consumption, use of anaerobic processes and aquatic respiration.

31
Q

How do animals increase oxygen storage?

A

Larger blood volume, higher haemoglobin content in blood and higher myoglobin content in muscle.

32
Q

How do animals decrease oxygen consumption?

A

Decrease metabolism and heart rate.

33
Q

How do animals use anaerobic processes?

A

Switch to lactic acid formation.

34
Q

How do animals use aquatic respiration?

A

Cutaneous (frog and sea snakes) and oesophageal or rectal respiration (some turtles).

35
Q

What triggers diving reflex in humans?

A

Chemoreceptors on face and nostrils activated by contact with cold water, carried along 5th cranial nerve to the brain.

36
Q

Diving reflex

A

Stop breathing, reduce heart rate, peripheral vasoconstriction and splenic contraction.

37
Q

Cardiovascular changes in diving

A

Peripheral resistance increases as a result of a change in the blood vessels caused by catecholamines of the SNS and bradycardia also occurs.

38
Q

Metabolic rate change when diving in seals

A

If no change occurred, seal would use up oxygen in five minutes versus the average 20 minute dive.

39
Q

Lactic acid formation

A

Most muscles receive no blood in a dive, so work based on anaerobic processes causing lactic acid formation and accumulation in the muscle, this is immediately shifted to blood after a dive and is gradually removed.

40
Q

How is lactic acid removed?

A

Synthesised into glycogen by liver and muscles or into carbon dioxide and wate

41
Q

Origin of diving reflex

A

Found in all air-breathing vertebrates, associated with transition to air-breathing at birth and has a similar response to fish out of water.

42
Q

Effects of high pressure

A

Increase in pressure causes dissociation of weak acids and bases, changes in protein structure, contractile effects of muscles and impacts gases.

43
Q

Longest underwater dive

A

11:54.

44
Q

Static apnea depth record

A

214m.

45
Q

Two types of changes to adapt to environments

A

Purely physiological or genetic.

46
Q

Link of mammals/birds and aquatic species

A

Most mammalian orders and birds have an aquatic representative such as monotrema have the aquatic platypus and ostriches have the penguin.

47
Q

Depths dived by whales, seals and turtle

A

Sperm whale can dive 2,000m, Southern elephant seal can dive 1,620m and Leatherback turtle can dive 1,280m.

48
Q

Weddell seals diving behaviour

A

Dive for 10-20 minutes

49
Q

Elephant seals diving behaviour

A

Dive for 30-40 minutes but up to 120 mins.

50
Q

Emperor penguins diving behaviour

A

Dive for up to 22 minutes.

51
Q

Whales diving behaviour

A

Can dive up to 2 hours.

52
Q

Animals evolutionary adaptations to aid diving

A

Increase oxygen levels, decrease oxygen requirements and evolve countermeasures for other issues.

53
Q

How do diving animals increase oxygen availability?

A

Increased muscle myoglobin (up to 60% of O2 in muscle), increase haematocrit by 10-20% and increase spleen volumes which act as red blood cell reservoirs.

54
Q

What is haematocrit a measure of?

A

Percentage of blood sample that is RBC.

55
Q

Human oxygen stores

A

45% respiratory, 40% blood and 15% muscle.

56
Q

Sperm whale oxygen stores

A

7% respiratory, 60% blood and 33% muscle.

57
Q

Weddell seal oxygen stores

A

5% respiratory, 65% blood and 30% muscle.

58
Q

How do animals lower oxygen requirements?

A

Bradycardia, peripheral vasoconstriction, reduced hepatic and renal perfusion, colder temperature can reduce circulation and cost-efficient locomotor activity.

59
Q

Weddell seal gliding

A

Gliding dives are much more oxygen efficient than stroking dives.

60
Q

How have animals evolved countermeasures to the bends?

A

Whales and seals breathe out before diving and store only 7% oxygen in their lungs, with lung collapse at depth and less perfusion prevents nitrogen and oxygen transfer while at the depths.

61
Q

How do diving animals prevent nitrogen narcosis?

A

They have reduced lung volumes with a modified bronchiolar structure that is more muscular allowing for closing of air passages.

62
Q

How can animals reduce sensitivity to pCO2?

A

Holding breath causes a rise in CO2 levels causing increase in blood pH, so evolved blood with high buffering capacity.

63
Q

Oxygen-Hb dissociation curve in penguins vs ducks

A

Shifted to the left in penguins so haemoglobin is saturated at higher pO2 and stripped at lower pO2 allowing for oxygenation in hypoxic environments.

BIOL2018:Adaptive Physiology (10 decks)

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