Quiz - 25 - Diving Knowledge Workbook - Diving Physiology

[Pedro Burrito]

From the Diving Physiology Section of the PADI Diving Knowledge Workbook Version 2.02 © PADI 2009:

Objective 2.8 - Define the term "silent bubbles" as it relates to decompression sickness.

Question 3

Silent bubbles are thought to form because of the presence of:

a. fat particles in the blood stream.

b. impurities in the diver's air supply.

c. gas "seeds" (micronuclei).

d. changes in blood chemistry brought about by high levels of nitrogen.​

I will post a daily question from my exams to help newer divers and to encourage more experienced divers to interact gracefully and helpfully with the newer divers.

Reminder - this is a post in the Basic Forum and it is a green zone. Please be nice and on topic.

Thank you for your patience while we try to give people something to discuss other than Covid-19 and/or Politics. I will post the answer covered by the spoiler tag later today.

 

[scubadada]

Really?

 

[Pedro Burrito]

Really?

Yes, it's a question in the book. I didn't change anything.

 

[boulderjohn]

Notice the wording--"thought to" rather than "proven to."

ScubaBoard has a connection to this. For many years the "Ask Doctor Decompression" forum was handled by Dr. Michael Powell, one of the key researchers for the PADI RDP. That research revealed the extent of the bubbling, and it struggled to explain it. Dr. Powell is no longer active on ScubaBoard, but I remember well a thread on this topic in which he explained that the answer to this question was what he still firmly believed but could never prove.

 

[elmo]

Notice the wording--"thought to" rather than "proven to."

This begs the question, "thought to by whom?" My neighbour might think it's caused by drinking carbonated drinks. They'd be wrong, but that's beside the point when it comes to a "thought to" question, where the 'thinker' is not specified.

 

[TMHeimer]

These questions are from 2009 Workbook. The one I got is 2008. Most are probably the same in 2020.... If you're a DMC now it's like having all the answers to the test....

 

[Couv]

Delete...wrong thread.

 

[Pedro Burrito]

Spoiler: Answer

c. gas "seeds" (micronuclei).

Just as rain drops require dust particles on which to form, it is theorized that nitrogen bubbles need some form of "seed". These seeds are termed gas micronuclei - unwettable microscopic gas pockets on tissue surfaces that act as "seeds" for bubble growth.