From earliest times, people have sought to understand the nature of life. We instinctively want to know how our bodies work, how we are born, how we grow and develop, the nature of illness, what happens when we die. Physiology describes the nature of life. It provides the framework for studying and exploring the bases of life. Physiologists view life from the simplest to the most complex levels of organisation - from the subcellular, to the whole person. Physiologists make an important contribution to areas such as heart disease, reproduction and ageing and global population control.