What many Christians call the Last Supper was the last Passover meal that Jesus ate before He was crucified. When He said the unleavened bread was His body, He was explaining how the Passover pointed to Him and His sacrifice. Remember Jesus calling Himself the Bread of Life (John 6:35)? Also, the Passover Bread the Jews used then (and now!) was striped (By His stripes we are healed), has many holes in it (He was pierced for our iniquities), and the scorch marks resemble bruises (He was bruised for our transgressions). In the Passover, the bread is passed out to all participating, the rest is symbolically buried, then later "resurrected".
Almost every aspect of the Passover has a direct correlation to Jesus' sacrifice and Resurrection.
Almost every aspect of the Passover has a direct correlation to Jesus' sacrifice and Resurrection.