Human Senses and Sensory Receptors Flashcards

Vocabulary flashcards covering the anatomy and physiology of general and special senses as presented in Chapter 16 lecture notes.

Sensation

Information received from sensory receptors.

Perception

The conscious awareness of a sensation.

Receptive Field

The specific area monitored by a single receptor cell; smaller fields allow for more precise stimulus localization.

Adaptation

A decreased sensitivity to a continuous stimulus, which can be tonic (slow) or phasic (fast).

Chemoreceptors

Sensory receptors that detect chemicals dissolved in fluids, such as those in the respiratory system monitoring $pH$ and gas levels.

Nociceptors

Pain receptors that detect tissue damage; they consist of free nerve endings and are widely distributed except for in the brain.

Thermoreceptors

Free nerve endings that detect temperature changes; cold receptors are $3-4 imes$ more numerous than warm receptors.

Warm Receptors

Thermoreceptors that detect temperatures between $25-45^{ ext{o}} ext{C}$ ($77-113^{ ext{o}} ext{F}$); temperatures above $45^{ ext{o}} ext{C}$ trigger burning sensations.

Cold Receptors

Thermoreceptors that detect temperatures between $10-20^{ ext{o}} ext{C}$ ($50-68^{ ext{o}} ext{F}$); temperatures below $15^{ ext{o}} ext{C}$ trigger freezing sensations.

Mechanoreceptors

A category of receptors that respond to touch, pressure, vibrations, and stretch, including baroreceptors and proprioceptors.

Baroreceptors

Mechanoreceptors located in the aortic arch and carotid sinuses that monitor blood pressure by detecting pressure changes.

Proprioceptors

Receptors located in muscles, tendons, and joints that detect body positioning, posture, and movement.

Muscle Spindles

A type of proprioceptor that detects stretch in skeletal muscle.

Golgi Tendon Organs (GTO)

Proprioceptors that detect stretch in tendons and act primarily as tonic adaptors.

Tactile Discs (Merkel’s discs)

Unencapsulated, extremely sensitive tonic receptors for light touch and pressure located in the basal layer of the epidermis.

Tactile Corpuscles (Meissner’s corpuscles)

Encapsulated phasic adaptors located in dermal papillae that recognize fine texture and shape through light touch.

Bulbous Corpuscles (Ruffini corpuscles)

Encapsulated tonic receptors located in the dermis and subcutaneous layer that detect deep pressure and skin distortion.

Lamellated (Pacinian) Corpuscles

Large encapsulated phasic receptors that detect deep pressure, pulsing, or high-frequency vibrations.

Referred Pain

Inaccurate localization of sensory signals where signals from viscera are perceived as originating from the skin or muscle.

Photoreceptors

Receptors in the retina that detect changes in light intensity, color, and movement; consists of rods and cones.

Olfactory Receptor Cells

Bipolar primary neurons in the sensory pathway for smell that contain olfactory hairs projecting into the nasal cavity.

Lingual Papillae

Epithelial projections on the tongue surface; types include Vallate, Foliate, Fungiform, and Filiform.

Filiform Papillae

Papillae on the anterior $2/3$ of the tongue surface that provide friction for moving objects but contain no taste buds.

Umami

A pleasant, savory taste sensation detected by gustatory receptor cells.

Conjunctiva

The mucous membranes of the eye consisting of the palpebral and bulbar layers.

Aqueous Humor

A clear watery fluid in the anterior cavity of the eye that bathes and nourishes the lens.

Vitreous Humor

A clear gel-like fluid in the posterior cavity of the eye that helps retain eye shape and stabilizes the retina.

Fibrous Tunic

The tough outer layer of the eye composed of the transparent cornea and the white sclera.

Vascular Tunic

The middle layer of the eye containing the choroid, iris, and ciliary body.

Optic Disc

The 'blind spot' of the retina where ganglion axons exit toward the brain and no photoreceptors are present.

Fovea Centralis

A central pit within the macula lutea that contains the highest proportion of cones and provides the sharpest vision.

Cones

Photoreceptors numbering approx. $6 ext{ million}$ per eye that provide color vision and high acuity in intense light.

Rods

Highly sensitive photoreceptors numbering approx. $125 ext{ million}$ per eye that provide black-and-white vision in dim light.

Accommodation

The process by which the lens changes shape to focus light on the retina for near or distant vision.

Myopia

Nearsightedness; a condition where the image is focused in front of the retina, requiring a diverging (concave) lens for correction.

Hyperopia

Farsightedness; a condition where the image is focused beyond the retina, requiring a converging (convex) lens for correction.

Ceruminous Glands

Glands in the external ear that secrete waxy cerumen to trap foreign objects and impede bacterial growth.

Auditory Tube (Eustachian Tube)

A passage connecting the middle ear to the nasopharynx that equalizes air pressure on both sides of the tympanic membrane.

Auditory Ossicles

The three small bones of the middle ear—malleus, incus, and stapes—that transmit and amplify sound waves.

Perilymph

A fluid similar to cerebrospinal fluid found between the bony and membranous labyrinths of the inner ear.

Endolymph

A fluid high in $K^+$ (similar to intracellular fluid) found within the membranous labyrinth.

Spiral Organ

The sensory receptor organ for hearing located within the Cochlear duct (scala media).

Pitch

The perception of sound based on frequency, measured in Hertz ($Hz$); humans are most sensitive to $1500-4000 ext{ Hz}$.

Ampulla

An enlarged area at the base of each semicircular canal that houses the crista ampullaris for detecting angular acceleration.

Utricle and Saccule

Saclike components of the vestibule that contain maculae for detecting static equilibrium and linear acceleration.

Otoliths

Densely packed 'ear stones' located on the otolithic membrane that shift position during head tilt to stimulate macular receptors.