Sensory Receptors and Special Senses

Comprehensive vocabulary flashcards covering general and special senses, cutaneous receptor subtypes, and the detailed anatomy and physiology of the eye and the ear.

General Senses

Receptors widely distributed throughout the body—including tactile receptors in the skin, joints, and muscles—with no specialized organ structure.

Special Senses

Senses located exclusively in the head region, including taste (gustation), smell (olfaction), sight (vision), and hearing (audition).

Small Receptive Field

A sensory area that provides precise, sensitive localization, containing a high density of receptors and dedicated sensory cortex (e.g., in the palms, fingers, and face).

Large Receptive Field

A broad sensory area with fewer, widely spaced receptors (such as on the trunk, arms, and legs) that covers a wide range of area with less precise localization.

Cutaneous Receptors

Sensory receptors situated within the skin, comprising mechanoreceptors, nociceptors, and thermal receptors.

Mechanoreceptors

Receptors that detect physical movements and vibrations, including tactile skin receptors, receptors along hair follicles, and hair cells in the cochlea.

Mechanical Nociceptors

Pain receptors activated by strong mechanical stimuli such as pinching, squeezing, or sharp penetrating objects, transmitted to the brain via A-delta fibers.

Thermal Nociceptors

Pain receptors activated by extreme temperatures—specifically noxious heat above $45^\circ\text{C}$ and cold below $5^\circ\text{C}$—as well as strong mechanical stimuli, transmitting signals through A-delta fibers.

Polymodal Nociceptors

Pain receptors activated by noxious mechanical stimuli, extreme heat, extreme cold, or irritating chemicals, producing a slow, dull burning pain transmitted via unmyelinated C fibers that persists long after stimulus removal.

Thermal Receptors

Receptors widely distributed throughout the body that detect changes in temperature and regulate the activation or inactivation of sweat glands.

Chemoreceptors

Receptors that detect molecules that diffuse across a membrane and bind to specific receptor sites for smell or taste.

Baroreceptors

Receptors located in the carotid bodies, aortic arch, and medulla that detect changes in pressure, primarily monitoring blood pressure.

Rods

Photoreceptors on the retina that detect light and cover the vast majority of the retina from the ora serrata toward the center.

Cones

Photoreceptors concentrated directly in the center of the retina that detect color by responding to distinct wavelengths and frequencies of light.

Proprioceptors

Sensory receptors found in joints and ligaments that relay information about limb position and body awareness.

Cornea

The clear, translucent anterior portion of the sclera (the outermost layer of the eye) that allows light to enter.

Ciliary Body

A muscular ring connected to the lens by suspensory ligaments that adjusts the shape and thickness of the lens for focusing at various depths.

Ora Serrata

A flower-patterned anatomical boundary on the retina that separates the anterior segment from the posterior (vitreous) cavity.

Fovea Centralis

A small indentation in the macula at the back of the retina responsible for fine focusing of incoming images.

Optic Disc

The blind spot located at the back of the eye where the retina transitions into the optic nerve, devoid of photoreceptors.

Lingual Papillae

The surface projections on the tongue, categorized into circumvallate across the back, filiform down the center, and fungiform around the edges.

Eustachian Tube

An auditory canal connecting the middle ear to the back of the throat that equalizes pressure on both sides of the tympanic membrane.

Conduction Deafness

Hearing impairment resulting from the fusing or disarticulation of the middle ear ossicles (malleus, incus, and stapes), which impedes sound vibration transmission.

Membranous Labyrinth

The inner channel system of the semicircular canals and cochlea, filled with endolymph fluid.

Bony Labyrinth

The outer channel system surrounding the membranous labyrinth of the inner ear, filled with perilymph fluid.

Organ of Corti

The sensory structure located inside the scala media of the cochlea, lined with stereocilia that convert liquid vibrations into nerve impulses.