Singular / Plural Nouns

Dear sir,

I have some inquiries about the choice of noun form (singular or plural) to be used with a plural possessive determiners (their, our, etc.) I have sought the advice of some native speakers on the following 4 sentences only to become more confused as they have different opinions. It is really really frustrating.

1a. There are many cells in *our body*.
1b. There are many cells in *our bodies*.

2a. We do this in *our everyday life*.
2b. We do this in *our everyday lives*.

A Canadian native speaker and a reply from ASKOXFORD advised that only (1b) and (2b) are correct.
An American professor of English advised that I should use (1a) and (2a) to 'avoid the problem of thinking that we have more than one body apiece' and likewise with 'life'.
A reply from Englishclub.com advised that all four are acceptable.

Whose opinion is correct or more reliable? The professor's?
Is there such a thing as 'the ultimate authority' in English from which/whom I can seek advice? Please help.

I have seen the use of plural possessive determiners with singular noun in some books and on the Net. So does that make such use acceptable?


In Longman Dictionary of Common Errors (Turton & Heaton, 1996), there is this sentence:
1. This example shows how computers affect *our everyday life*. (pg 122)


In Collins Cobuild English Dictionary for Advanced Learners (3rd ed, 2001):
1. All of us in *our daily life* react favourably to people who take us and our
views seriously. (pg 377)

2. ...*our body's* sensory system (pg 1411)

3. People also use 'heart' to refer to the area of *their chest* that is closest
to *their heart*. (pg 725)


In Biology; The Unity and Diversity of Life (10th ed., Starr & Taggart, 2003, Thomson Brooks/Cole):
1. Tuataras are like modern amphibians in some respects of *their brain* and in their way of walking. (pg 457).
2. Chameleons rely on *their tongue*, which is longer than *their body*. (pg 456)


On the Net, at the website of SocietyGuardian.co.uk:
1. People wait for years,decades, in pain, in the faint hope that one day they will receive the call from the hospital that will return *their life* to normal.

2. It assumes that change is difficult without reference to the subject's family, school, and - for priests - transition to the seminary, their experiences there and *their life* as *a priest*.

Michael Swan's Practical English Usage says that for generalisations and rules, it is OK to use singular or plural nouns or both together with 'their/our'. So, is it applicable here?

Thank you.
Ryan

I think we could say " You have no blood in your veins", couldn't we?

Thanks guys.

I sought help from usingenglish.com too. The teacher there said that there only the second sentences are correct. He said the professor was 'perhaps, the original nutty professor' and the englishclub.com person didn't understand my question.

But unluckily he didn't answer all my question, eg. is there such thing as 'the ultimate authority' in English?

If he is right, then Collins Cobuild English Dictionary for Advanced Learners and Longman Dictionary of Common Errors and the Biology textbook published by Thomson/Brooks-Cole are all using poor English?

Personally I trust the editorial capability of these publishers!