Special Senses

Vocabulary flashcards covering sensory receptor classifications, smell, taste, vision, hearing, and equilibrium structures and pathways.

Free nerve endings

Sensory nerve endings without a connective tissue capsule that are widely distributed and detect pain, temperature, and some touch.

Encapsulated nerve endings

Nerve endings enclosed in connective tissue, mostly functioning as mechanoreceptors to detect pressure, vibration, and stretch.

Mechanoreceptors

Sensory receptors that respond to pressure, stretch, or movement.

Chemoreceptors

Sensory receptors that respond to chemicals, including those for smell and taste.

Thermoreceptors

Sensory receptors that detect temperature change.

Nociceptors

Sensory receptors that detect potentially damaging stimuli and signal pain.

Photoreceptors

Sensory receptors that respond to visible light.

Osmoreceptors

Sensory receptors that detect the osmotic concentration of body fluids.

Exteroceptors

Receptors located near the body surface that respond to external stimuli.

Interoceptors

Receptors located within organs that monitor the internal environment.

Proprioceptors

Receptors located in muscles, tendons, and joints that signal body position and movement.

Olfactory epithelium

The specialized sensory lining located high in the nasal cavity containing olfactory receptor neurons.

Olfactory cilia

Structures on olfactory receptor neurons where dissolved odorant molecules bind to receptors.

Papilla

A projection on the surface of the tongue that contains taste buds.

Taste bud

A small sensory organ containing gustatory receptor cells.

Taste pore

The opening at the surface of a taste bud through which dissolved tastants reach gustatory hairs.

Flavour

The sensory perception combining taste with smell, texture, touch, and temperature.

Conjunctiva

An accessory eye structure that lines the eyelids and keeps the eye surface moist.

Extrinsic muscles

Eye muscles that attach outside the eyeball and move it.

Iris muscles

Intrinsic eye muscles that change pupil diameter to regulate light entry.

Ciliary muscle

An intrinsic eye muscle that controls lens shape for focusing.

Sclera

The fibrous outer tissue layer of the eyeball wall.

Choroid

The vascular middle tissue layer of the eyeball wall.

Retina

The inner sensory neural tissue layer of the eyeball wall.

Aqueous humor

Watery fluid located in the anterior cavity of the eye.

Vitreous humor

Gel-like fluid located in the posterior cavity of the eye.

Refraction

The change in direction of light as it passes between transparent media.

Accommodation

The process by which the lens becomes more curved to focus on a near object.

Convergence

The inward turning of both eyes toward the same near object.

Neural signal in retina

The pathway of neural information in the retina: photoreceptor -> bipolar cell -> ganglion cell -> outgoing axon.

Rods

Photoreceptors that are highly sensitive in dim light, responsible for light-and-dark peripheral vision.

Cones

Photoreceptors that require brighter light and provide colour vision and sharp detail.

Fovea centralis

The area of the retina with the highest cone concentration, providing sharp vision in good light.

Visual pathway

The neural route of vision: Retina -> Optic nerve -> Optic chiasma -> Optic tract -> Thalamus (lateral geniculate nucleus) -> Optic radiations -> Visual cortex (occipital lobe).

Middle ear ossicles

Three tiny bones—malleus, incus, and stapes—that transmit vibrations from the tympanic membrane to the oval window.

Auditory tube

A structure connecting the middle ear to the throat that helps equalize pressure.

Organ of Corti

The hearing structure located in the cochlear duct on the basilar membrane that contains hair cell receptors.

Static equilibrium

The perception of head position relative to gravity and linear acceleration, detected by maculae in the utricle and saccule.

Dynamic equilibrium

The perception of rotational or angular movement, detected by cristae ampullares in the semicircular ducts.