Chapter 8: Sensory Receptors Flashcards

50 vocabulary flashcards covering Chapter 8 sensory receptors, including eye/ear anatomy, visual/auditory pathways, equilibrium, chemoreception, tactile/thermoreceptors, pain, and proprioceptors.

Sensory adaptation

The decrease in frequency of action potentials in a sensory neuron even when the stimulus is maintained, resulting in a decreased response to that stimulus.

Photoreceptors

Sensory receptors classified by the energy they transduce that respond to light energy.

Mechanoreceptors

Sensory receptors classified by the energy they transduce that respond to mechanical energy such as touch, pressure, and vibration.

Chemoreceptors

Sensory receptors that detect chemical substances in the air, food, and water.

Thermoreceptors

Free nerve endings that detect temperature changes.

Nociceptors

Free nerve endings sensitive to stimuli that may be perceived as painful.

Cornea

The transparent layer that covers the front of the eye and is continuous with the sclera.

Sclera

A tough membrane that envelops the eyeball, continuous with the cornea.

Choroid

A black coat covering the internal surface of the eye that prevents light rays from scattering.

Aqueous humor

The fluid filling the anterior cavity of the eye.

Vitreous humor

The thicker fluid filling the posterior cavity of the eye.

Iris

Structure that regulates the amount of light entering the eye by contracting or dilating the pupil.

Lens

The transparent, elastic structure through which light passes to form an image on the retina.

Extrinsic muscles

The six muscles that permit the eyes to move together to focus on an object.

Ciliary body

Structure consisting of the ciliary process and ciliary muscle that attaches to the lens via suspensory ligaments.

Accommodation

The ability to change the curvature of the lens to clearly focus on a close or far object.

Rods

Photoreceptors in the retina sensitive to dim light that detect shape and movement, but not color.

Cones

Photoreceptors in the retina sensitive to color, most concentrated in the fovea.

Fovea

The region of sharpest vision where cones are most concentrated.

Optic disk

The area where the optic nerve passes out of the eyeball.

Rhodopsin

Visual pigment in rods that breaks down when exposed to light, leading to sensory transduction.

Optic chiasm

The region in the floor of the hypothalamus where optic nerves cross.

Lateral geniculate nucleus

Nucleus of the thalamus where axons of the optic nerves end before messages transmit to the visual cortex.

Primary visual cortex

Region located in the occipital lobe of the cerebrum that receives visual messages from the lateral geniculate nucleus.

Tympanic membrane

Structure separating the outer ear from the middle ear that vibrates in response to sound waves.

Auditory ossicles

Three small bones in the middle ear—malleus, incus, and stapes—that amplify sound waves.

Eustachian tube

Tube connecting the middle ear with the nasopharynx to equalize pressure on both sides of the tympanic membrane.

Bony labyrinth

Outer inner-ear structure composed of the cochlea, vestibule, and semicircular canals filled with perilymph.

Membranous labyrinth

Group of ducts and sacs contained within the bony labyrinth and filled with endolymph.

Perilymph

Fluid in the bony labyrinth that surrounds the inner membranous labyrinth.

Endolymph

Fluid contained within the membranous labyrinth of the inner ear.

Organ of Corti

Structure in the cochlea containing hair cells that converts pressure waves into nerve impulses for transmission to the brain.

Tectorial membrane

Membrane overhanging the hair cells in the organ of Corti.

Basilar membrane

Membrane in the cochlea upon which the hair cells in the organ of Corti rest.

Vestibule

Organ of equilibrium containing the saccule and utricle.

Otoliths

Small calcium carbonate stones housed in the saccule and utricle that detect gravity.

Cupula

A gelatinous mass surrounding the tips of hair cells in equilibrium receptor cells.

Semicircular canals

Inner ear organs of equilibrium that provide information about turning movements.

Cristae

Clumps of hair cells within each ampulla stimulated by movements of the endolymph.

Olfaction

The sense of smell, which depends on chemoreceptors in the nasal cavity.

Gustation

The sense of taste, sensed by taste buds in papillae on the tongue.

Olfactory epithelium

The lining of the upper part of the nasal cavity that contains olfactory receptors.

Odorants

Chemical substances that can be smelled.

Papillae

Small elevations on the tongue containing taste buds.

Tactile receptors

Receptors located in various parts of the skin that respond to touch, pressure, and vibration.

Substance P

A neurotransmitter secreted alongside glutamate by sensory neurons transmitting messages regarding painful stimuli.

Endorphins and enkephalins

Endogenous opiates that inhibit neurons transmitting pain signals in the spinal cord.

Phantom pain

Pain perception that occurs when a severed nerve is stimulated.

Referred pain

Pain perception that occurs when the brain interprets an incoming message as coming from the body surface rather than an internal organ.

Proprioceptors

Receptors that allow perception of the position of the body and its parts, including muscle spindles, Golgi tendon organs, and joint receptors.