A&P 1 - Module 12 (Special Senses)

Sense

The ability of the body to detect a stimulus (change in the environment).

General Sense

A sense in which the receptor is distributed throughout the body (e.g., touch, pressure, temperature, pain, proprioception).

Special Sense

A sense in which the receptor is located with a specialized organ (e.g., vision, hearing, equilibrium, taste, and smell).

Sensation

The activation of sensory receptors by a stimulus, leading to a neural signal sent to the central nervous system.

Perception

The conscious awareness of sensory information processed in the brain.

Receptive Field

The region within which a particular sensory neuron can be activated by a given stimulus.

Peripheral Adaptation

A process by which sensory receptors reduce their response to a constant stimulus over time.

Central Adaptation

A process by which the central nervous system decreases its perception of a constant stimulus over time.

Olfactory System

The sensory system responsible for the sense of smell; odorants detected by olfactory receptor cells in the nasal cavity.

Gustatory System

The sensory system responsible for the sense of taste; chemical stimuli detected by gustatory receptor cells within taste buds of the tongue.

Visual System

The sensory system responsible for vision; light detected by photoreceptors in the retina of the eyes.

Auditory System

The sensory system responsible for hearing; sound waves detected by hair cells within the cochlea of the inner ear.

Vestibular System

The sensory system responsible for recognizing linear and rotational body movement; movement detected by hair cells in the inner ear.

Odorant

An air-borne chemical that is capable of activating olfactory receptors to produce a perception of smell.

Olfactory Bulb

The bulbous structure located on the underside of the frontal lobe of the brain where olfactory receptor cells (olfactory nerve, CN I) synapse with secondary neurons.

Olfactory Tract

One of two bundles of axons extending from the olfactory bulb to brain regions involved in odor perception and response.

Basal (Stem) Cells

The stem cells found in the olfactory epithelium or gustatory taste buds that regenerate olfactory and gustatory receptor cells.

Olfactory Nerve (CN I)

The cranial nerve formed by olfactory receptor cells that transmits sensory information related to smell from the nasal cavity to the olfactory bulb.

Tongue

A muscular organ in the mouth involved in taste, speech, and food manipulation.

Lingual Papillae

Projections of the epithelial surface of the tongue that contain taste buds.

Taste Bud

A cluster of gustatory receptor cells and supporting cells responsible for detecting taste stimuli.

Gustatory Receptor

A sensory receptor located within a taste bud that is activated by taste stimuli (dissolved chemicals).

Gustatory Receptor Cell

A specialized cell within the taste bud that binds dissolved tastants and transmits signals to afferent sensory neurons.

Tastant

A chemical capable of activating a gustatory receptor to produce a perception of taste.

Umami

One of the five basic taste modalities, associated with the savory flavor of amino acids like glutamate; 'delicious' or 'tasty' (Japanese).

Iris

The pigmented muscular structure in the eye that controls the diameter of the pupil.

Pupil

The opening in the center of the iris that allows light to enter the eye and reach the retina.

Sclera

The white, fibrous outer layer of the eyeball that provides protection and shape.

Anterior Cavity

The smaller, fluid-filled space in the eye located between the cornea and the lens, containing aqueous humor.

Posterior Cavity

The larger space in the eye located behind the lens, filled with vitreous humor.

Focal Point

The point at which light rays converge after passing through the lens, ideally focused on the retina for clear vision.

Accommodation

The process by which the lens changes shape in order to position the focal point on the retina, thereby focusing on near or distant objects.

Myopia

The condition of nearsightedness, where distant objects appear blurry due to the focal point being anterior to the retina.

Hyperopia

The condition of farsightedness, where close objects appear blurry due to the focal point being posterior to the retina.

Rod Photoreceptor

A type of photoreceptor cell in the retina that is activated by light intensity, useful in low light and responsible for night vision.

Cone Photoreceptor

A type of photoreceptor cell in the retina that is activated by light wavelength (i.e., color), useful in bright light.

Optic Disc

The region at the back of the eye where the optic nerve (CN II) exits; known as the 'blind spot' due to lack of photoreceptors.

Macula

The central region of the retina, lateral to the optic disc, which contains a high density of photoreceptors and is responsible for sharp central vision.

Fovea Centralis

The central region of the macula which contains densely packed cone photoreceptors only.

Depth Perception

The ability to judge the distance and three-dimensional relationship of objects based on overlaid visual input from both eyes.

External Ear

The outer part of the ear including the auricle and external acoustic meatus.

Middle Ear

The air-filled chamber between the tympanic membrane and cochlea which contains the auditory ossicles and transfers auditory signals from the external to inner ear.

Inner Ear

The fluid-filled structure within the temporal bone that contains the cochlea for hearing and vestibular system for balance.

Auricle

The external, visible part of the ear that collects and directs sound waves into the auditory canal; pinna (zoology).

External Acoustic (Auditory) Meatus

The canal leading from the external ear to the tympanic membrane; ear canal.

Ceruminous Gland

A gland located in the external auditory canal that secretes earwax (cerumen) to protect the ear.

Tympanic Membrane

A thin membrane that separates the external ear from the middle ear and vibrates in response to incoming sound waves; eardrum.

Auditory Ossicles

Three small bones in the middle ear (malleus, incus, stapes) that transmit sound vibrations to the inner ear.

Malleus

The first of the auditory ossicles, attached to the tympanic membrane; 'hammer.'

Incus

The middle auditory ossicle, connecting the malleus to the stapes; 'anvil.'

Stapes

The third auditory ossicle that transmits vibrations to the oval window of the cochlea; 'stirrup.'

Auditory Tube

A canal that connects the middle ear to the nasopharynx, helping to equalize pressure; eustachian tube, pharyngotympanic tube.

Oval Window

An oval-shaped, membrane-covered opening in the cochlea where the stapes transmits sound vibrations into the inner ear.

Cochlea

A spiral-shaped structure in the inner ear that contains the sensory receptors for hearing.

Semicircular Canals

Three loop-shaped structures in the inner ear involved in sensing rotational movements of the head.

Vestibule

The central part of the inner ear between the cochlea and semicircular canals involved in detecting linear movement and head position.

Hair Cell

A specialized mechanoreceptor in the inner ear that responds to movement of fluid or membrane deflection.

Stereocilia

The small, hair-like projections on the surface of hair cells that detect mechanical movement.

Kinocilium

A single, larger cilium found on hair cells that helps determine the direction of movement.

Semicircular Ducts

Fluid-filled ducts within the semicircular canals.

Ampulla

The expanded region at the base of each semicircular duct containing hair cells that respond to fluid movement during head rotation.

Utricle

An otolith organ in the vestibule that detects horizontal linear movement and head position.

Saccule

An otolith organ in the vestibule that detects vertical linear movement and head position.