How do you avoid dead air space problems?

Breathe slowly and deeply.

What is the name of the lung overexpansion injury that occurs when a lung collapses?

a) pneumothorax
b) subcutaneous emphysema
c) air embolism
d) convulsion

a) pneumothorax

If a diver complains of DCI symptoms immediately on reaching the surface, what is the most likely cause? 

A lung overexpansion injury

How do skin divers prepare for a breath hold dive? 

They use deep-stomach breathing

What is the blanket term that covers both lung overexpansion injuries and Decompression sickness?

Decompression Illness

What is the first aid procedure for a lung overexpansion injury?

Contact emergency medical services
Keep the patient lying level, administer Oxygen ( 100 pct. if possible ) and monitor the patients breathing.

Why do you feel discomfort in your ears while descending?

Pressure pushing your eardrum and surrounding tissues inwards.

What symptoms are likely if you were to rupture your ear drum?

It can cause severe vertigo

What part of the ear is most affected while descending?

The middle ear

 If you are having difficulty with ear equalization, and you blow too hard against a pinched nose
you could cause what injury?

A round window rupture.

I hope that you enjoyed the PADI IDC Revision – Physiology. The questions that you found on this page are very common questions used on most PADI exams.
For more help, sign up for my Distance Learning Preparation course, and I’ll help you to get right up to speed in both PADI dive Theory, and PADI Standards.

There are some more PADI IDC Revision – Physiology questions here:

If a diver had a tight neck seal, what would be the likely cause of light headedness?

Carotid sinus reflex

What is a pressure related injury called? ( It can happen on both ascent and descent )  

Barotrauma.  If we were to analyse this word.. we have Bar ( pressure ) and Trauma ( Injury )
So, put them together and we have Barotrauma = Pressure related injury.

On a hot day, a diver in a full suit is complaining of nausea. He is sweating and has cool, clammy skin. Is he suffering from Heat Stroke..  OR  Heat Exhaustion?

He is suffering from Heat Exhaustion.  Heat Stroke is worse than Heat Exhaustion. With heat stroke, there would be no more sweating, and the diver would have dry skin.
So remember! Stroke is worse than Exhaustion.

What is the name given to tiny bubbles of Nitrogen that can found in a divers blood after a dive, although no symptoms can be found ?

Silent Bubbles.