Heart
noun
The heart internal organs is the heart, of course.
しんぞう
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
電話恐怖症みたいなのがあって、電話で話をする時に心臓がバクバクするんです。
I have a kind of telephone phobia and my heart starts beating very fast whenever I talk on the phone.