Exam 1 : Chapter 15 terms

Orbit

Bony cavity containing the eyeball

Eyeball

Hollow, fluid-filled sphere composed of three tunics

Sclera

White outer layer of dense fibrous connective tissue; maintains shape, protects internal structures, provides muscle attachment

Cornea

Transparent anterior portion of fibrous tunic; allows light entry and refracts light

Anterior chamber

Space between cornea and iris filled with aqueous humor

Posterior chamber

Space between iris and lens filled with aqueous humor

Aqueous humor

Fluid that maintains intraocular pressure, nourishes structures, and contributes to refraction

Lens

Transparent biconvex structure that refracts light

Ciliary muscle

Smooth muscle controlling lens shape

Iris

Colored part of eye that controls amount of light entering pupil

Pupil

Opening in iris allowing light into eye

Sphincter pupillae

Circular smooth muscle that constricts pupil; parasympathetic control

Dilator pupillae

Radial smooth muscle that dilates pupil; sympathetic control

Ciliary body

Contains ciliary muscles and ciliary processes

Ciliary processes - Produce aqueous humor and attach to suspensory ligaments

Suspensory ligaments - Attach lens to ciliary body

Scleral venous sinus - Drains aqueous humor into venous circulation

Vitreous chamber - Chamber posterior to lens filled with vitreous humor

Vitreous humor - Jelly-like substance maintaining eye shape and holding retina/lens in place

Choroid - Pigmented vascular layer supplying retina with oxygen and nutrients

Tapetum lucidum - Reflective layer enhancing night vision in some animals

Retina - Nervous tunic containing photoreceptors

Photoreceptors - Rods and cones detecting light

Rods - Photoreceptors for dim light and peripheral vision

Cones - Photoreceptors for color and sharp vision

Macula lutea - Central retinal area responsible for detailed vision

Fovea centralis - Area of sharpest vision with highest cone concentration

Bipolar cells - Neurons between photoreceptors and ganglion cells

Ganglion cells - Neurons whose axons form the optic nerve

Optic disc - Blind spot where optic nerve exits eye

Rhodopsin - Visual pigment in rods composed of retinal and opsin

Retinal - Light-absorbing molecule in rhodopsin

Opsin - Protein component of rhodopsin

Rhodopsin cycle - Series of changes occurring when light activates rhodopsin

Dark adaptation - Increased sensitivity of eyes in darkness

Light adaptation (photoreception) - Adjustment to bright light when photoreceptors are stimulated

Refraction - Bending of light as it passes through structures of the eye

Color vision - Vision produced by cone stimulation

Optic nerve - Cranial nerve II carrying visual information to brain

Visual pathway to brain - Retina → optic nerve → optic chiasm → optic tract → thalamus → visual cortex

Auricle - External ear structure collecting sound waves

External acoustic meatus - Ear canal carrying sound to tympanic membrane

Tympanic membrane - Eardrum vibrating in response to sound waves

Auditory tube - Tube equalizing pressure between middle ear and throat

Malleus - First auditory ossicle attached to tympanic membrane

Incus - Middle auditory ossicle

Stapes - Auditory ossicle contacting oval window

Vestibule - Inner ear region involved in static equilibrium

Semicircular canals - Structures involved in dynamic equilibrium

Cochlea - Spiral inner ear structure responsible for hearing

Perilymph - Fluid within bony labyrinth

Endolymph - Fluid within membranous labyrinth

Round window - Membrane relieving pressure within cochlea

Oval window - Membrane receiving vibrations from stapes

Bony labyrinth - System of bony passages in inner ear

Membranous labyrinth - Membrane-filled ducts within bony labyrinth

Vestibulocochlear nerve - Cranial nerve VIII for hearing and equilibrium

Static labyrinth - Structures detecting gravity and linear acceleration

Dynamic labyrinth - Structures detecting rotational movement

Crista ampullaris - Receptor for rotational equilibrium

Ampulla - Enlarged region of semicircular canal containing crista ampullaris

Cupula - Gelatinous structure covering hair cells in ampulla

Kinocilium - Largest cilium on vestibular hair cell

Stereocilia - Hair-like projections involved in equilibrium and hearing

Saccule - Structure detecting vertical acceleration

Utricle - Structure detecting horizontal acceleration

Utricular macula - Receptor region in utricle

Saccular macula - Receptor region in saccule

Otoliths - Calcium carbonate crystals involved in static equilibrium

Pathways for equilibrium sensations - Hair cells → vestibular nerve → CN VIII → brainstem/cerebellum

Cochlear duct (scala media) - Endolymph-filled duct containing Organ of Corti

Scala vestibuli - Upper perilymph-filled chamber of cochlea

Scala tympani - Lower perilymph-filled chamber of cochlea

Spiral Organ (Organ of Corti) - Hearing receptor organ containing hair cells

Inner hair cells - Main sensory receptors for hearing

Outer hair cells - Amplify sound vibrations

Basilar membrane - Membrane supporting Organ of Corti

Tectorial membrane - Gel-like membrane contacting stereocilia

Helicotrema - Opening connecting scala vestibuli and scala tympani

Sound waves - Vibrations traveling through medium

Wavelength - Distance between sound wave peaks

Frequency - Number of sound waves per second

Pitch - Perception of sound frequency

Amplitude - Height/intensity of sound wave

Auditory pathways - Cochlea → cochlear nerve → CN VIII → brainstem → auditory cortex

Olfactory epithelium - Specialized epithelium containing smell receptors

Olfactory bipolar neurons (olfactory receptors) - Sensory neurons detecting odorants

Olfactory nerves - Nerve fibers carrying smell information to olfactory bulb

Smell transduction - Conversion of odorant stimulation into nerve impulses

Odorants - Chemicals stimulating smell receptors

Olfactory discrimination - Ability to distinguish different odors

Olfactory adaptation - Decreased sensitivity to continuous odors

Olfactory pathway to brain - Olfactory receptors → olfactory bulb → olfactory tract → olfactory cortex

Taste buds - Structures containing gustatory receptor cells

Papillae - Tongue projections containing taste buds

Filiform papillae - Papillae without taste buds

Fungiform papillae - Mushroom-shaped papillae with taste buds

Foliate papillae - Leaf-shaped papillae with taste buds

Vallate papillae - Large papillae containing many taste buds

Taste (gustatory) cells - Receptor cells for taste