01. What are the two major functions of the ears?

• Sound and Balance
• Balance – body position with respect to gravity and acceleration

02. There are three distinct areas in the ear. To which one is the Eustachian tube attached?

• The areas in the ear are - outer, middle, inner
• Eustachian tube is attached to the middle ear

03. What is the function of the Eustachian tube?

• Maintain equal pressure on both sides of the ear drum

04. Briefly explain what happens when a diver equalise?

• By swallowing, moving the jaw, or doing the Valsalva manoeuvre, the closed Eustachian tube is opened, letting air into the middle ear, equalizing the pressure on both sides of the ear drum

05. What can prevent a diver from clearing his/her ears?

• Cold, hay fever or infection, creating nasal congestion causing inflammation and/or narrowing of the Eustachian tube, means that no air comes through

06. Why should a diver never wear earplugs when diving?

• It may create airspace between the earplug and the ear drum, which can’t be equalised

07. What are sinuses?

• Four sets of air cavities connected to the nasal cavities
• Frontal, Sphenoid, Ethmoidal, Maxillary

08. How does a blocked sinus affect the diver?

• It can cause extreme pain

09. Your buddy indicates that s/he cannot descend because of a pain in his/her forehead. What do you suggest?

• Abort the dive, following ascend procedures, as sinus pain/squeeze can't be equalised away

10. What are the two main gases exchanged in respiration?

• Oxygen and carbon dioxide

11. Where does this exchange take place?

• The exchange takes place in the millions of alveoli in the lungs and the capillaries that envelop them

12. What carries the oxygen to every living cell in the body?

• Haemoglobin (protein) in the red blood cells carries oxygen
• One molecule Haemoglobin carries 4 molecules oxygen

13. Trace the pathway of air from the atmosphere to blood

• Air > Atmosphere > Alveoli > Capillaries (oxygen / carbon dioxide exchange) > Blood

14. Describe briefly the circulatory system

• The main "components" of the circulatory system are: The Heart, Arteries, Veins, and Capillaries
• Right side of heart - pumps venous blood through lungs - pulmonary circulation
• Left side of heart - pumps oxygenated blood throughout body - systemic circulation
• Veins are formed by joined up capillaries to carry venous blood
• Arteries carries oxygenated blood to body
• Capillaries are small blood vessels allowing exchange of gases and fluids to/from tissue cells

15. Outline the pathway of oxygen from the blood capillaries in the lungs to the brain

• Blood Capillaries > Left Atrium > Left Ventricle > Arteries (Carotid Artery) > Brain

16. What is the diaphragm and what is its role in breathing?

• The diaphragm contracts when you inhale, creating a vacuum effect that pulls air into the lungs, and it relaxes when you exhale, pushing air out of the lungs

17. Describe briefly the heart and how it functions

• The heart has four chambers
• Oxygen rich blood comes in on the high pressure (left) side to the collecting chamber (left atrium) down to the pumping chamber (left ventricle) and out to head, trunk and limbs through arteries.
• Venous blood comes in on the low pressure (right) side through veins from head, trunk and limbs, to the collecting chamber (right atrium) to the pumping chamber (right ventricle) to each lung for carbon dioxide / oxygen exchange

18. Name at least three pulse points in the body

• Wrist > radial artery
• Neck > carotid artery
• Upper arm > brachial artery

19. What is the normal resting heart rate of an adult?

• 60-80 beats per minute

20. What is the normal resting breathing rate of an adult?

• 15-18 inhales per minute

21. What is the average lung volume in litres in an adult?

• 6.5 litres of air

22. Explain the term 'residual volume'.

• Air still contained in the lungs after maximum expiration

23. What is the difference between hypoxia and anoxia?

• Hypoxia - varying degrees of oxygen deficiency
• Anoxia - total lack of oxygen

24. What are the greatest contributors to hypoxia?

• Free entry of air to lungs is impeded
• Disease affecting the lungs, such as emphysema
• Blood unable to take up enough oxygen due to reduced haemoglobin content (gas poisoning, pneumonia)
• Heart disease reducing circulation of oxygenated blood

25. How long can the brain last without oxygen?

• About 6 minutes

26. List at least three causes, which may interfere with ventilation.

• Muscular bulk of the tongue, dropping back blocking the pharynx
• Foreign material such as dirt, debris, dentures, chewing gum, broken teeth, blood
• Strangulation
• Asthma or severe allergies
• Inhalation of smoke
• Deprivation of oxygen (drowning, house fires, etc.)

27. Explain what you understand by shallow water blackout.

• Underwater faint due to lack of oxygen to the brain by holding your breath long
• Hypoxia, effectively

28. What is the first aid for near drowning?

• Remove victim from submersion
• If required - EAR (Expired Air Resuscitation)
• If required - CPR (CardioPulmonary Resuscitation)
• 100% Oxygen
• Treat for shock
• Remove victim to hospital
• Inform medical staff of submersion details - type of water, duration, time it happened

29. 100% oxygen should be given in all cases of near drowning. True or false? Explain your answer.

• True
• The level of hypoxia can’t easily be determined on location, so 100% oxygen is administered to aid systemic circulation

30. What is dry drowning?

• Involuntary breath holding
• Victim in panic inhales water, but a spasmatic closure of the larynx occurs

31. What is the difference between salt and freshwater drowning?

• Fresh water dilutes the blood - increases blood volume with chemical imbalance, leading to diminished heart function, and finally the heart action stops
• Salt water clogs up the blood - the salt attracts additional fluids, lack of volume forces the heart to work harder, eventually cardiac arrest will occur

32. In the case of a near drowning where a casualty appears to recover fully. Is it necessary to bring the casualty to hospital? Why?

• Hospital, laboratory and medical assessment is always needed
• Secondary drowning is known to occur - lung collapse, heart complications

33. What is the normal core body temperature?

• 37 Celsius

34. What does the term hypothermia mean?

• Normal body temperature drops below 37 degrees

35. Where is the body core?

• Chest area

36. Where is the temperature control regulator of the body located?

• The hypothalamus in the brain

37. When entering cold water many divers experience an urge to urinate. Suggest a physiological reason for this.

• When temperature falls, the hypothalamus sends signals to get rid of excess fluids to avoid heating of fluids - diuresis

38. List the combination of conditions, which can lead to hypothermia.

• Cold weather, wet and wind in combination can result in hypothermia

39. Explain vasoconstriction.

• The body closes off blood supply to the outer extremities to focus on vital inner organs

40. What is the treatment for hypothermia?

• Remove victim from the cold - ideally while in huddle position
• Place victim in exposure bag or wrap in wind breaker or plastic bag or sheet
• If required, huddle around victim
• Strip victim off wet clothes and replace with dry clothes as soon as possible

41. What steps can be taken to avoid hypothermia?

• Being properly insulated from cold, wind and wet
• Not wasting heat and energy by over exertion
• Acclimatisation to cold over a long period of time

42. Where is the site of greatest heat loss in the body?

• The head - no insulation like body fat

43. A diver has just pulled a casualty from the very cold water and cannot detect a pulse. Is it prudent to start CPR? Why?

• Yes
• Only a doctor can declare a victim dead, and only after rewarming

44. Vigorously rubbing casualty, warming with hot water bottles, and giving alcohol are considered dangerous ways to treat a hypothermic casualty. Discuss.

• It can cause blood capillaries to open up and send cold blood from outer regions to body core and again lower the core temperature

45. When is a diver sure the casualty has recovered from hypothermia?

• The onset of sweating