What is citta in the four frames of reference?

I am trying to understand the four frames of reference. I could understand the body. I could comprehend the sensations (to be honest not completely). I could not understand the mind (citta). This has been my observation. I'm sensitive to noises. I feel irritation (sensation) and anger generated towards the person who created it, and the mind stays angry and continues to in that way. Is this what citta is ? That which continues to be in that state even after the sensation that caused it ceased to exist ?