The Heart
The heart is a commonly used phrase throughout the Bible. Therefore, it is worth studying the verses which mention the matter of the heart to see the context and meaning for such a term.
In general the heart is composed of four aspects of our being: the mind, emotion and will (of the soul) and the conscience (of the spirit).
mind
Matthew 9:4
Hebrews 4:12
Genesis 6:5
will
Acts 11:23
Hebrews 4:12
emotion
John 16:22
conscience
Hebrews 10:22
1 John 3:20