8 Terminology of the Endocrine and Sensory Systems

How to decode medical terms

Medical terms often combine a prefix at the beginning, a root or combining form at the core, and a suffix at the end. A combining form is a root joined to a vowel—usually “o”—to make pronunciation easier. For example, aden/o means “gland,” while -megaly means “enlargement.” Not every term can be translated part by part, so unfamiliar terms should be checked in a reliable medical dictionary.

A practical decoding strategy

A useful approach is to start with the suffix, which often identifies a condition, procedure, or specialty. Then identify the root or combining form for the body structure, check the prefix for amount, position, or quality, and combine the meanings into a clear phrase. Confirm the resulting definition in context.

For example, hyperthyroidism can be analyzed as hyper- (“excessive”) + thyroid (thyroid gland) + -ism (“condition”). The parts suggest a condition involving excessive thyroid activity, but word-part meanings provide clues rather than replacing the full clinical definition.

Endocrine system terminology

The endocrine system consists of glands and other tissues that release hormones. Hormones travel in the bloodstream and help regulate processes such as growth, metabolism, and reproduction. Major endocrine glands include the pituitary, thyroid, parathyroids, adrenals, pineal, and pancreas; the ovaries and testes also produce hormones.

Common endocrine word parts include:

• aden/o: gland.

• adren/o, adrenal/o: adrenal gland.

• endocrin/o: endocrine system or internal secretion.

• glyc/o, gluc/o: sugar or glucose.

• pituitar/o: pituitary gland.

• thyr/o, thyroid/o: thyroid gland.

• hyper-: excessive or above normal.

• hypo-: deficient or below normal.

• -crine: to secrete.

• -emia: blood condition.

• -logy: study of.

• -megaly: enlargement.

• -pathy: disease or disorder.

Interpreting endocrine terms

These examples show how endocrine terms combine word parts:

• Hypersecretion combines hyper- (“excessive”) with secretion and means release of an excessive amount of a substance, such as a hormone.

• Hyposecretion combines hypo- (“deficient”) with secretion and means release of too little.

• Endocrinology combines endocrin/o with -logy and names the study and medical specialty concerned with the endocrine system.

• Acromegaly combines acr/o (“extremities”) with -megaly (“enlargement”). It is a disorder characterized by enlargement of certain body parts, commonly associated with excess growth hormone in adulthood.

Endocrine abbreviations

Common abbreviations include TSH for thyroid-stimulating hormone, T4 for thyroxine, and DM for diabetes mellitus. Abbreviations may have more than one meaning across settings, so interpret them in context and follow the documentation standards used by the relevant organization.

The eye and its terminology

The special senses include sight and hearing. The eye focuses light and converts it into signals that travel from the retina through the optic nerve to the brain. In hearing, sound vibrations pass through the outer and middle ear to the cochlea in the inner ear, where sensory cells convert them into signals carried to the brain. The inner ear also contains structures involved in balance.

Common eye combining forms and suffixes include:

• blephar/o: eyelid.

• conjunctiv/o: conjunctiva, the membrane covering the front of the eye and lining the eyelids.

• corne/o, kerat/o: cornea.

• ir/o, irid/o: iris.

• ocul/o, ophthalm/o: eye.

• opt/o: vision.

• retin/o: retina.

• scler/o: sclera; in other contexts, it may also mean hardening.

• dacry/o, lacrim/o: tears or tear duct.

• -opia: vision condition.

Interpreting eye terms

Examples of eye terms include:

• Conjunctivitis combines conjunctiv/o (conjunctiva) with -itis (inflammation) and means inflammation of the conjunctiva.

• Retinopathy combines retin/o (retina) with -pathy (disease) and means a retinal disease or disorder.

• Diplopia combines dipl/o (double) with -opia (vision condition) and means double vision.

The ear and its terminology

Common ear combining forms and suffixes include:

• acous/o, audi/o: hearing.

• aur/i, aur/o: ear.

• cochle/o: cochlea.

• mastoid/o: mastoid bone.

• myring/o, tympan/o: eardrum; tympan/o can also refer to the middle ear.

• ot/o: ear.

• staped/o: stapes, a middle-ear bone.

• vestibul/o: vestibule of the inner ear.

• -algia: pain.

• -itis: inflammation.

• -metry: process of measuring.

• -scope, -scopy: an instrument for viewing or the process of viewing.

Interpreting ear terms

These examples illustrate how ear-related parts indicate meaning:

• Audiometry combines audi/o (hearing) with -metry (measuring process) and means measurement or testing of hearing.

• Otalgia combines ot/o (ear) with -algia (pain) and means ear pain.

• Myringotomy combines myring/o (eardrum) with -tomy (incision) and means an incision into the eardrum.

Terms that do not decode transparently

Some terms name structures or conditions without using a transparent word-part pattern. Cataract, for example, names clouding of the eye’s lens and cannot be reliably decoded from the common word parts listed here. Learn such terms as whole words and check their definitions.