I'll answer this one backwards.
There are several medical professions that include needing to know about the physiology of the cardiovascular, blood, lymphatic, respiratory system and urinary system. The most popular ones include, a doctor, a nurse and my personal favorite (as I am one), a paramedic!
For these professions and others, it's important to know how they work in order to treat the patient according to their systems. You need to know how they work in relation to other systems of the body, as different symptoms will present differently within different system having problems.
