Final answer:
A heart murmur is caused by the turbulent flow of blood in the heart, and it can be caused by valvular heart disease, hypertension, and congenital heart defects.
Step-by-step explanation:
A heart murmur is caused by the turbulent flow of blood in the heart. It can be caused by various conditions such as valvular heart disease, hypertension, and congenital heart defects. Valvular heart disease refers to the malfunctioning of the heart valves, which can be caused by disease, trauma, or congenital defects. Hypertension, or high blood pressure, can contribute to the development of a murmur. Congenital heart defects are structural abnormalities present at birth that can also lead to the presence of a murmur.