cache lite and functions

[SeenGee]

I use an included functions page as a templating system for a website, two main functions pagetop() and pagebottom() provide a header and footer for each individual page like this:

require 'functions.php';
pagetop($pagename);

#Indivudal page content here

pagebottom();

I'm looking into cache options now to try and improve the speed of my site, i dont seem to be able to cache this content though because it comes from a function call. I've tried placing the cache code into functions.php and it runs without error but the page is not cacheing. Is it possible to cache the output from a php function in the same way that ordinary content can be cached?

Thanks.