Ch:13 Anatomy Key Terms

Accommodation: The process by which the curvature of the lens changes so the eye can focus on a near object Adaptation: The diminishing of a sensation that occurs after continuous exposure to a stimulus

Analgesic Drug used to relieve pain

Anterior cavity: Space between the lens and cornea of the eye; further divided into an anterior and posterior chamber

Aqueous humor: Clear, watery fluid that fills the anterior cavity of the eye

Astigmatism: Asymmetrical or uneven curvature of the cornea, causing light to be focused unevenly Auditory canal: Tube running from the outer ear to the middle ear

Auditory ossicles: Three small bones (the malleus, the incus, and the stapes) that connect the eardrum to the inner ear

Auricle: Visible part of the ear; also called the pinna Bony labyrinth: Complicated system of passageways within the temporal bone that contains the inner ear Canal of Schlemm: Vessel that collects aqueous humor from the anterior chamber of the eye and delivers it to surrounding blood vessels

Chemoreceptors: Receptors that react to various chemicals, including odors, tastes, and the concentration of various chemicals in the body Choroid: Highly vascular layer of tissue in the eye that supplies oxygen and nutrients to the sclera and retina

Ciliary body: Thickened extension of the choroid that secretes aqueous humor

Cochlea: Snail-like structure in inner ear that contains the structures for hearing

Cones: Photoreceptors in the retina responsible for color vision

Conjunctiva: Transparent mucous membrane that lines the eyelids and covers the anterior surface of the eyeball (except for the cornea) Convergence: The process by which the eyes move (often toward each other) so that light rays fall on corresponding spots on each retina Cornea: Transparent extension of sclera that sits over the iris and admits light into the eye

Depth perception: The ability to judge the distance of objects and the spatial relationship of objects at different distances

Emmetropia: When light rays focus on the retina without the need for a corrective lens; normal vision Endotymph: Fluid occupying the inside of the membranous labyrinth Equilibrium: The state of physical balance

Eustachian tube: Passageway from middle ear to nasopharynx External acoustic meatus: Opening of the auditory canal to the outside of the body Fast pain fibers: Produce sharp, localized, stabbing-type pain at the time of injury; abundant in the skin and mucous membranes Fovea centralis: Depressed area in the middle of the macula lutea that contains only cones; it is the area of sharpest vision Frequency: The number of sound waves that occur during a specific time frame; determines the pitch of a sound

Gustation: Sense of taste

Hyperopia: When light rays focus at a point behind the retina; farsightedness

Iris: Ring of colored muscle in the middle layer of the eye; regulates the diameter of the pupil Lacrimal apparatus: Structure consisting of the lacrimal gland and a series of tear ducts Lacrimal gland: Small gland that

secretes tears Lacrimal punctum: Tiny pore at the end of each lacrimal canal that drains tears into the lacrimal canals Macula lutea: Center point of the retina

Mechanoreceptors: Receptors that respond to factors that change the position of a receptor Membranous labyrinth: Lines the inside of the bony labyrinth

Myopia: When light rays focus in front of the retina; nearsightedness Nasolacrimal duct: Passageway that carries tears into the nasal cavity Nociceptors: Pain receptors that respond to tissue damagc Crom trauma as well as from heat, chemicals, pressure, or a lack of oxygen

Olfaction: Scnsc of smell

Olfactory bulbs: Pair of structures residing underneath the brain's frontal lobe

Optic chiasm: Point in the brain where half the optic nerve fibers cross to the opposite sidc of the brain

Optic disc: Spot where nerve fibers leave the retina, converging to become the optic nerve

Optic nerve: Nerve exiting from the posterior portion of the eyeball; transmits signals to the brain Organ of Corti: Hearing sense organ Oval window: Opening that leads from the middle ear to the vestibule of the inner ear Palpebral fissure: The opening between the eyelids Papillae: Protrusions on the tongue on which taste buds are located Perilymph: Fluid that cushions the space between the bony and membranous labyrinth Photopupillary reflex: Reflex that causes the pupils to constrict automatically when exposed to bright light

Photoreceptors: Receptors in the eyes that respond to light Posterior cavity: Large cavity in the eye lying posterior to the lens and the anterior cavity

Presbyopia: When light rays focus behind the retina, creating difficulty focusing on objects up close

Proprioceptor: Receptor found in skeletal muscle, joints, and tendons that provide information about body movement, muscle stretch, and the general orientation of the body Pupillary constrictor: Muscle encircling the pupil that works to narrow the pupil Pupillary dilator: Muscle within the iris that works to widen the pupil Receptors: Structures specialized at detecting a stimulus

Referred pain: Pain felt in a part of the body other than its actual source Refraction: Bending of light rays so they focus on the retina

Retina: Innermost layer of the eye that contains receptors for vision

Rods: Photoreceptors in the retina active in dim light

Sclera: Outermost layer of the eye; formed from dense connective tissue Semicircular canals: Three fluidfilled bony channels in the inner ear Slow pain fibers: Produce a dull, aching pain; found on deep body organs and structures Tarsal glands: Glands along the thickened area at the edge of the eye that secrete oil to slow the evaporation of tears Thermoreceptors: Receptors activated by a change in temperature Tympanic membrane: Membrane separating outer ear from middle ear that vibrates in response to sound waves; eardrum

Vestibule: Structure at the entrance of the bony and membranous labyrinths; contains organs necessary for sense of balance Visual acuity: The sharpness of visual perception Vitreous humor: Jelly-like

substance that fills the posterior cavity of the eye