Wind down and loosen up

[Etern1ty]

What's the difference between "wind down" and "loosen up"?
Dictionary says: wind down - to rest or relax after a period of activity or excitement, and, loosen up - to relax and stop worrying.
So, for example, if you're nervous about something at work, or before an exam, you must "loosen up", and if you have been working hard, mm, digging ground, or playing football, and you want to relax, you should "wind down"?
Wind down isn't related to "nervous", when "loosen up" like a.. "calm down"?
And what is the past form of loosen up, loosened up?
Thanks in advance

[nitikasnv]

Hi,

Wind down:Become quiet or calm, especially after a state of agitation.

Wind loose:Become less tense, less formal, or less restrained, and assume a friendlier manner.

I think they are different.

Thanks