The Body and the Blood of Christ together with His Soul and His Divinity and
therefore the Whole Christ are truly present in the Eucharist.

One indeed is the universal Church of the faithful, outside which no one at all is saved, in which the priest himself is the sacrifice, Jesus Christ, whose body and blood are truly contained in the Sacrament of the altar under the species of bread and wine; the bread (changed) into His body by the divine power of transubstantiation, and the wine into the blood, so that to accomplish the mystery of unity we ourselves receive from His (nature) what He Himself received from ours. (Lateran Council IV, DS 802)

If anyone denies that in the sacrament of the most holy Eucharist there are truly, really, and substantially contained the body and blood together with the soul and divinity of our Lord Jesus Christ, and therefore the whole Christ, but shall say that He is in it as by a sign or figure, or force, let him be anathema. (Council of Trent, DS 1651)

Christ becomes present in the Sacrament of the Altar by the transformation of the whole substance of the bread into His Body and of the whole substance of the wine
into His Blood.

If anyone says that in the sacred and holy sacrament of the Eucharist there remains the substance of bread and wine together with the body and blood of our Lord Jesus Christ, and denies that wonderful and singular conversion of the whole substance of the bread into the body, and of the entire substance of the wine into the blood, the species of the bread and wine only remaining, a change which the Catholic Church most fittingly calls transubstantiation, let him be anathema. (Council of Trent, DS 1652)

The Worship of Adoration (latria) must be given to Christ present in the Eucharist.

If anyone says that in the holy sacrament of the Eucharist the only-begotten Son of God is not to be adored even outwardly with the worship of latria (the act of adoration), and therefore not to be venerated with a special festive celebration, nor to be borne about in procession according to the praiseworthy and universal rite and custom of the holy Church, or is not to be set before the people publicly to be adored, and that the adorers of it are idolators, let him be anathema. (Council of Trent, DS 1656)

For the worthy reception of the Eucharist the state of grace as well as the proper and pious disposition are necessary.

If anyone says that faith alone is sufficient preparation for receiving the sacrament of the most Holy Eucharist, let him be anathema. And that so great a Sacrament may not be unworthily received, and therefore unto death and condemnation, this holy Council ordains and declares that sacramental confession must necessarily be made beforehand by those whose conscience is burdened by mortal sin, however contrite they may consider themselves. If anyone moreover teaches the contrary or preaches or obstinately asserts, or even publicly by disputation shall presume to defend the contrary, by that fact itself he is excommunicated. (Council of Trent, DS 1661)