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HSE Scuba > Chapter 2 - Physics And Physiology Of Diving > Flashcards

Chapter 2 - Physics And Physiology Of Diving Flashcards

1
Q

What is the pressure at sea level?

A

1 kg/cm^2-

1 bar

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2
Q

What is the pressure like 5000m above sea level?

A

0.5 bar

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3
Q

What happens when you increase depth by 10m?

A

The pressure increases by 1 bar

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4
Q

What is ambient pressure?

A

Pressure of air around you

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5
Q

What is absolute pressure?

A

Pressure in total measured against a vacuum.

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6
Q

What is gauge pressure?

A

Pressure measured on a gauge calibrated to zero at sea level. Gauge pressure is zero when absolute pressure is 1 bar

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7
Q

How can you calculate absolute pressure?

A

Absolute pressure = gauge pressure + atmospheric pressure

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8
Q

How can you remember the difference between gauge and absolute pressure?

A

When your tank is empty the gauge pressure is 0 but the absolute pressure is 1 bar

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9
Q

How can you calculate absolute pressure?

A

Depth (m) / 10 + atmospheric pressure

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10
Q

How can you work out depth?

A

Depth = (absolute pressure - atmospheric pressure) x 10

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11
Q

What are the units of capacity/volume?

A

Litre

1000l = 1 cubic metre

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12
Q

What is the mass of 1 L of fresh water equivalent to?

A

1 kg

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13
Q

What are the units of pressure?

A

1 bar - 1 kg per square cm

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14
Q

What is the density of salt water and density of fresh water?

A

1030 kg/m3

1000 kg/m3

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15
Q

What is boyles law?

A

Volume of a given mass varies inversely to its absolute pressure as long as temperature remains constant.

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16
Q

How does boyles law work?

A

As pressure increases the volume decreases

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17
Q

How can boyles law be stated?

A

P1 V1 = P2 V2

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18
Q

Where is the greatest change of pressure?

A

Within the first 10m

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19
Q

What is barotrauma?

A

Pressure damage

20
Q

Which tube in the middle ear allows you to equalise?

A

The Eustachian tube

21
Q

What is the valsalva manoeuvre?

A

Ear clearing

22
Q

What are the symptoms of barotrauma caused by decent?

A

An experience of vertigo, nausea and anxiety

23
Q

If water enters the ear from barotrauma how long can the recovery time be?

A

1-3 months

24
Q

What is reversed ear?

A

When the pressure in the middle ear is greater than the outer ear

25
Q

Why should you not dive with a cold?

A

You can have nosebleeds or other fluids escaping your nose in the water

26
Q

What is the metabolism equation?

A

Food + oxygen = energy + waste products removal (water and co2)

27
Q

What is the total lung capacity of the average human?

A

6 litres

28
Q

What is the residual volume?

A

The 1-1 1/2 litres of air that must remain in the lungs so they keep the correct shape

29
Q

What is the vital capacity?

A

The 4 1/2 - 5 litres that represents the maximum amount of air that can be inhaled and exhaled in one respiratory cycle

30
Q

What is the tidal volume?

A

The amount of air inhaled and exhaled

31
Q

What is the tidal volume at rest?

A

0.5litres

32
Q

What is the dead air space?

A

The portion of the tidal volume that plays no part in the gas exchange

33
Q

What is an oral nasal shroud used for?

A

Used in full face masks to reduce the dead air space

34
Q

What is the average number of breaths per minute?

A

12-20

35
Q

How many breaths do you take per minute when exercising?

A

35

36
Q

What causes you to take a breath?

A

The rising levels of carbon dioxide in the blood

37
Q

What are the characteristics of blood?

A

It’s both solid (45%) and liquid (55%)

38
Q

What is the liquid part of the blood?

A

Plasma - 90-92% water

39
Q

What is the solid element of the blood like?

A

Made from…
Thrombocytes (platelets) - natural clotting
Erythrocytes (red blood cells) - carry oxygen
Leucocytes (white blood cells) - defend against germs and infections

40
Q

What are the functions of the blood?

A

Transportation
Clotting to minimise the loss of body fluids
Defence system
Regulate body temperature - vasodilation or vasoconstriction

41
Q

What does blood transport?

A 
Oxygen from lungs to tissue
CO2 from tissues to lungs
Nutrients from the digestive tract to the cells
Waste products 
Hormones and enzymes
42
Q

What is the cardiac cycle?

A
  1. Blood returns via the vena cava to the right atrium
  2. Passes to the right ventricle
  3. Pumped out of the heart into the pulmonary artery to the lungs
  4. Gas exchange
  5. Oxygenated blood returns to the left atrium
  6. Blood passes to the left ventricle
  7. Blood is pumped into the aorta for body distribution
43
Q

What is the rule of thumb around blood transportation?

A

Veins carry de-oxygenated blood to the heart
Arteries carry oxygen rich blood away from the heart

The exception is the pulmonary vessels

44
Q

What is the average pulse rate?

A

60-90 beats per minute

45
Q

What are the 3 types of blood vessels?

A

Arteries - thick muscular walls - cope with blood being pumped under pressure
Veins - very little muscular tissue - May have semi-lunar valves to prevent the back flow of blood
Capillaries - small vessels - permit the transfer of fluids, nutrients and gasses

46
Q

What is Archimedes principle?

A

A body immersed in a fluid experiences an up thrust equal to the mass of the fluid displaced

47
Q

What happens with the different types of buoyancy?

A

Positive - float
Neutral - hover
Negative - sink

HSE Scuba (13 decks)

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