What are medical specialties?

Branches of medicine that concentrate on the physiology and diseases ofor injuries to particular systems within the body.

For example, Cardiology is concerned with the heart and circulatory system, a Dentist treats tooth and gum problems. (The clues are the Latin roots in the titles.)

A curiOSity about the spelling: the British Word is "specialities" - with a central i - but the UK's National Health Service seems to have adopted the American spelling as in thequestion, for some reason.