I would suggest that only the name of the committee be put placed in bylaws. Standing Rules would be the proper place to put duties.
The needs of a P.T.O. might change too rapidly to have these duties of chairmen and committees put in bylaws. Standing rules are easier and quicker to change.
Officer duties DO need to be enumerated in bylaws however.

I need some help!!
We're in the process of drafting our bylaws and we have several committees headed by volunteer chairpersons.
I need to "beef up" the duties of each committee to more than the 1 line we currently show in our document.
I need suggestions on where to look for "the beef"!!