Functions like passover and other festivals used to - our reminder of God's faithfulness.
Also a memorial going up to the Lord (to 'remind' him) and our anticipation of the consummation, and more.
Just think about the elements from a life perspective as well as a theological concept perspective...
Bread - food for life
Wine - drink for life, and rest (alcohol more than a mere necessity, it symbolises Sabbath)
etc!
