Revision and assessment
0 of 2 hands-on
01 Introduction
This lesson brings the whole course together. Use the cards and the table below to check what you remember, then try the review questions. When you feel ready, take the final exam.
Objectives
- Recall the main body systems and conditions covered in this course
- Apply the physiology to short scenarios
- Prepare for the final exam
02 Watch
Course review
5 min · Video in production
- 1
A fast tour of the body underwater: lungs, circulation, ears, sinuses, tissues, brain.
- 2
For each system, one image of what goes right and one of what can go wrong.
- 3
A list of the key habits: breathe continuously, equalise early, ascend slowly, stay hydrated, stay within limits, be honest.
- 4
A preview of the final exam format and pass mark.
03 Learn
The course at a glance
| Topic | Key idea | Main habit |
|---|---|---|
| Breathing and circulation | Lungs have no muscle; denser gas is harder to move | Breathe slowly, deeply and continuously |
| Gas exchange | Carbon dioxide drives breathing; oxygen can drop without warning | Never skip breathe; stop and rest if breathless |
| Air spaces | Boyle's Law acts on ears, sinuses, lungs, mask and suit | Equalise on descent; never hold your breath on ascent |
| Ears and sinuses | The Eustachian tube must be opened actively | Equalise early, often and gently; never dive blocked |
| Nitrogen and decompression | Nitrogen dissolves at depth and must leave slowly | Ascend slowly, make a safety stop, stay hydrated |
| Narcosis and oxygen | Narcosis is reversible; oxygen toxicity depends on partial pressure | Stay within training depth; ascend if confused |
| Temperature, hydration, fatigue | Water takes heat about 25 times faster than air | End the dive when cold; drink steadily |
| Health and fitness | Some conditions are unsafe under pressure | Be honest; see a doctor with diving knowledge |
Emergencies to remember
- Lung overexpansion injury, chest pain, confusion or paralysis after surfacing: oxygen and emergency services at once.
- Suspected decompression sickness, however mild: oxygen, emergency services, recompression, no more diving.
- Vertigo underwater: stop, hold on to something and end the dive in a controlled way.
- Strong shivering or confusion from cold: end the dive and warm up.
Common mistakes
- Thinking that stopping to rest or sit out a dive is a failure.
- Treating a computer as a guarantee that decompression sickness cannot happen.
- Relying on a decongestant to dive with a cold.
- Holding the breath 'just for a moment' on a shallow ascent.
- Thinking that narcosis only matters for deep, technical divers.
Exam guide
The final exam draws questions from every lesson. You need at least 80% to pass, and you must answer all the safety-critical questions correctly (marked "critical" in your review afterwards). If you do not pass, you will see which lessons to revisit.
04 Explore
Try it yourself
Flip the cards to test your recall.
Flip each card to check your answer.
Tap a card to flip it.
05 Apply
Scenario
A friend says: "My dive computer says I am within limits, I have a mild cold but feel fine, and I took a decongestant. It is the last day, so I will fly home this evening after two morning dives."
What are the main concerns?
06 Check
07 Summary
Key points
- Breathe continuously, equalise early and gently, and ascend slowly.
- Know the emergencies: lung overexpansion, decompression sickness, vertigo and cold.
- Stay hydrated, rested and honest about your health. You can always call a dive.
- This course is theory only. Learn to dive with a qualified instructor.
Before you apply this in the water
- Have I been trained by a qualified instructor for this?
- Am I medically fit to dive?
- Do I have a buddy and a plan?
- Am I diving within my training and limits?
Answer every question in the Check section to mark this lesson complete.