Emotions and thoughts are a product of the brain. The brain helps to control heart rate and other processes in other organs of the body by way of the Autonomicnervous system, if I remember correctly.
As far as having innate courage, courage is just one of many personality traits that likely developed as a result of both natural (genetic) factors and nurture(environment). Everything a person thinks or does is a result of these two factors interacting in a complex way over time.
Even for a person who is not known to be very courageous, a circumstance where protecting another's life becomes important may spur that person to rapidaction. Even though a person may not have the courage or bravery to be a firefighter, that same person may still run into a burning house to save their pet orfriend.
Questions dealing with personality traits aren't so easily explained and there are rarely ever any black or white areas. Hopefully some psych majors onhere can shed more light on this because I still don't fully understand the workings of the brain.