Chapter 2 - Physics And Physiology Of Diving

Question 1

What is the pressure at sea level?

Answer 1

1 kg/cm^2-

1 bar

Question 2

What is the pressure like 5000m above sea level?

Answer 2

0.5 bar

Question 3

What happens when you increase depth by 10m?

Answer 3

The pressure increases by 1 bar

Question 4

What is ambient pressure?

Answer 4

Pressure of air around you

Question 5

What is absolute pressure?

Answer 5

Pressure in total measured against a vacuum.

Question 6

What is gauge pressure?

Answer 6

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

Question 7

How can you calculate absolute pressure?

Answer 7

Absolute pressure = gauge pressure + atmospheric pressure

Question 8

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

Answer 8

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

Question 9

How can you calculate absolute pressure?

Answer 9

Depth (m) / 10 + atmospheric pressure

Question 10

How can you work out depth?

Answer 10

Depth = (absolute pressure - atmospheric pressure) x 10

Question 11

What are the units of capacity/volume?

Answer 11

Litre

1000l = 1 cubic metre

Question 12

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

Answer 12

1 kg

Question 13

What are the units of pressure?

Answer 13

1 bar - 1 kg per square cm

Question 14

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

Answer 14

1030 kg/m3

1000 kg/m3

Question 15

What is boyles law?

Answer 15

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

Question 16

How does boyles law work?

Answer 16

As pressure increases the volume decreases

Question 17

How can boyles law be stated?

Answer 17

P1 V1 = P2 V2

Question 18

Where is the greatest change of pressure?

Answer 18

Within the first 10m

Question 19

What is barotrauma?

Answer 19

Pressure damage

Question 20

Which tube in the middle ear allows you to equalise?

Answer 20

The Eustachian tube

Question 21

What is the valsalva manoeuvre?

Answer 21

Ear clearing

Question 22

What are the symptoms of barotrauma caused by decent?

Answer 22

An experience of vertigo, nausea and anxiety

Question 23

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

Answer 23

1-3 months

Question 24

What is reversed ear?

Answer 24

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

Question 25

Why should you not dive with a cold?

Answer 25

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

Question 26

What is the metabolism equation?

Answer 26

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

Question 27

What is the total lung capacity of the average human?

Answer 27

6 litres

Question 28

What is the residual volume?

Answer 28

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

Question 29

What is the vital capacity?

Answer 29

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

Question 30

What is the tidal volume?

Answer 30

The amount of air inhaled and exhaled

Question 31

What is the tidal volume at rest?

Answer 31

0.5litres

Question 32

What is the dead air space?

Answer 32

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

Question 33

What is an oral nasal shroud used for?

Answer 33

Used in full face masks to reduce the dead air space

Question 34

What is the average number of breaths per minute?

Answer 34

12-20

Question 35

How many breaths do you take per minute when exercising?

Answer 35

35

Question 36

What causes you to take a breath?

Answer 36

The rising levels of carbon dioxide in the blood

Question 37

What are the characteristics of blood?

Answer 37

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

Question 38

What is the liquid part of the blood?

Answer 38

Plasma - 90-92% water

Question 39

What is the solid element of the blood like?

Answer 39

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

Question 40

What are the functions of the blood?

Answer 40

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

Question 41

What does blood transport?

Answer 41

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

Question 42

What is the cardiac cycle?

Answer 42

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

Question 43

What is the rule of thumb around blood transportation?

Answer 43

Veins carry de-oxygenated blood to the heart Arteries carry oxygen rich blood away from the heart The exception is the pulmonary vessels

Question 44

What is the average pulse rate?

Answer 44

60-90 beats per minute

Question 45

What are the 3 types of blood vessels?

Answer 45

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

Question 46

What is Archimedes principle?

Answer 46

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

Question 47

What happens with the different types of buoyancy?

Answer 47

Positive - float Neutral - hover Negative - sink