concept of dose - dopamine, oxytocin, serotonin, endorphins write on a book on wooden table

background biochemistry book business care chemical chemicals chemistry closeup colorful concept design desk dopamine dose drug education endorphin endorphins handwritten happiness happy health hormone hormones illustration isolated medical medicine mental message note notepad office oxytocin paper pharmacology physiology positive psychological psychology satisfaction science serotonin sign structure system table tablen text wood wooden workplace write