PHP merge multi dimensional array

Question

I have a multi dimensional array that looks like this...

Array
(
    [section1] => Array
        (
            [item1] => 0
            [item2] => 0
        )
    [section2] => Array
        (
            [item27] => 0
            [item8]  => 0
        )
)

I am trying to merge it so it looks like this..

Array
(
    [item1] => 0
    [item2] => 0
    [item27] => 0
    [item8]  => 0
)

I know I can loop through each and them add to a new array, but is there a built in PHP function I can use instead?