Chapter 15: The Special Senses - Vocabulary Flashcards

A complete list of vocabulary terms and definitions derived from Marieb Human Anatomy & Physiology 12th Edition Chapter 15 (The Special Senses).

Palpebrae

Thin, skin-covered folds that protect the eye anteriorly; also known as the eyelids.

Tarsal Glands

Modified sebaceous glands embedded in the tarsal plates that produce an oily secretion to lubricate the eyelids and eye; also known as Meibomian glands.

Conjunctiva

A transparent mucous membrane that lines the underside of the eyelids (palpebral conjunctiva) and covers the white of the eye (bulbar conjunctiva), producing a lubricating mucous secretion.

Lacrimal Apparatus

A system consisting of the lacrimal gland and ducts that secretes lacrimal fluid (tears) containing mucus, antibodies, and lysozyme, and drains it into the nasal cavity.

Sclera

The opaque, posterior portion of the fibrous layer of the eyeball that protects and shapes the eye and anchors extrinsic eye muscles.

Cornea

The transparent anterior one-sixth of the fibrous layer of the eye that allows light to enter and provides the majority of the eye's refractive (light-bending) power.

Choroid

The highly vascular, pigmented posterior region of the uvea that supplies blood to all eye layers and absorbs light to prevent visual confusion from light scattering.

Ciliary Body

A thickened ring of muscle and tissue surrounding the lens that controls lens shape via ciliary muscles and secretes aqueous humor via ciliary processes.

Iris

The colored, visible part of the eye located between the cornea and lens that contains smooth muscle layers controlling the size of the pupil.

Retina

The innermost layer of the eyeball, consisting of an outer pigmented layer and an inner neural layer containing photoreceptors, bipolar cells, and ganglion cells.

Rods

Photoreceptors in the retina that function in dim light and peripheral vision, providing noncolor vision with low visual acuity.

Cones

Photoreceptors located primarily in the central retina that operate in bright light, providing high-resolution, high-acuity color vision.

Fovea Centralis

A tiny pit in the center of the macula lutea containing only cones, serving as the region of highest visual acuity.

Optic Disc

The site on the posterior retina where ganglion cell axons exit the eye to form the optic nerve; lacks photoreceptors and is known as the blind spot.

Vitreous Humor

A clear, gel-like fluid filling the posterior segment of the eye that transmits light, supports the lens, holds the retina against the pigmented layer, and contributes to intraocular pressure.

Aqueous Humor

A plasma-like fluid continuously formed by ciliary processes in the anterior segment that supplies oxygen and nutrients to the lens and cornea before draining through the scleral venous sinus.

Accommodation

The active adjustment of the lens shape by ciliary muscles to increase light refraction for focusing on close objects.

Presbyopia

The loss of lens elasticity and accommodation capacity that naturally occurs with aging, typically over the age of 50.

Myopia

A refractive condition (nearsightedness) in which the eyeball is too long, causing light rays to focus in front of the retina; corrected with a concave lens.

Hyperopia

A refractive condition (farsightedness) in which the eyeball is too short, causing light rays to focus behind the retina; corrected with a convex lens.

Astigmatism

An unequal curvature in different parts of the cornea or lens that prevents light rays from focusing clearly, resulting in blurry vision.

Rhodopsin

The visual pigment found in the outer segment of rods, formed by the combination of 11-cis-retinal and opsin.

Phototransduction

The process by which visual pigments absorb photons of light energy and convert them into graded electrical potentials in photoreceptors.

Optic Chiasma

The X-shaped structure where medial fibers from the optic nerve of each eye cross over to the opposite side of the brain.

Olfactory Epithelium

The organ of smell located in the roof of the nasal cavity containing bipolar olfactory sensory neurons, supporting cells, and stem cells.

Mitral Cells

Second-order neurons located within the olfactory bulb glomeruli whose axons form the olfactory tract to conduct smell impulses to the brain.

Gustatory Epithelial Cells

Receptor cells for taste found within taste buds, possessing gustatory hairs that project through taste pores to detect dissolved tastants.

Papillae

Peglike projections of the tongue mucosa that house taste buds, including fungiform, foliate, and vallate varieties.

Tympanic Membrane

A thin, translucent connective tissue membrane separating the external ear from the middle ear that vibrates in response to sound waves; commonly called the eardrum.

Pharyngotympanic Tube

A canal connecting the middle ear cavity to the nasopharynx that opens during swallowing or yawning to equalize pressure across the eardrum; formerly called the eustachian tube.

Auditory Ossicles

Three small bones in the middle ear—malleus (hammer), incus (anvil), and stapes (stirrup)—that transmit and amplify sound vibrations from the eardrum to the oval window.

Bony Labyrinth

A system of tortuous channels in the temporal bone filled with perilymph, comprising the vestibule, semicircular canals, and cochlea.

Membranous Labyrinth

A continuous series of membranous sacs and ducts housed within the bony labyrinth that contain potassium-rich endolymph.

Spiral Organ

The receptor organ for hearing situated on the basilar membrane within the cochlear duct (scala media), containing inner and outer hair cells; also called the organ of Corti.

Maculae

Sensory receptor organs located in the saccule and utricle walls that monitor static equilibrium and head position relative to gravity.

Crista Ampullaris

The receptor region located in the ampulla of each semicircular canal that detects rotational or angular acceleration of the head.

Otoliths

Tiny calcium carbonate stones studded within the jelly-like otolith membrane of the maculae that increase the membrane's weight and inertia.

Presbycusis

An age-related type of sensorineural deafness resulting from the gradual loss and deterioration of hair cells in the spiral organ, initially affecting high-pitch perception.