Gerontology is the study of the elderly. A Ortho ped ist is a physician that treats bone disorders. The old terminology referring to children is no longer valid, but the term continues to be used today. The term has generally been replaced by Family Practitioner. A Oto laryngo logist is a physician that treats the ear, nose, and throat.
Ophthalmology is the study of the eye.
A Ophthalmo logist is a physican that treats diseases and disorders of the eye. Urology is the study of the urine or urinary tract. A Uro logist is a specialist in urology. Cardiology is the study of the heart. A physcian treating disorders of the heart is a Cardio logist.