Definitions of break down:

• verb:   collapse due to fatigue, an illness, or a sudden attack
• verb:   make ineffective

  Example: "Martin Luther King tried to break down racial discrimination"

• verb:   cause to fall or collapse
• verb:   lose control of one's emotions
• verb:   make a mathematical, chemical, or grammatical analysis of; break down into components or essential features
• verb:   separate (substances) into constituent elements or parts
• verb:   fall apart
• verb:   stop operating or functioning