Sensory Organs and Sensory Transduction

A set of vocabulary flashcards covering the sensory receptor mechanisms, vision, taste, smell, cutaneous/pain sensation, and auditory structures from the lecture notes.

Energy transduction

The process by which a sensory receptor absorbs a small amount of energy from a stimulus in the environment and converts it into electrical energy.

Receptor potential

A graded response in membrane potential where the extent of change depends on the energy of the stimulus.

Sensory adaptation

A decrease in the frequency of action potentials in a sensory neuron over time, even though a continued, constant stimulus is maintained.

Sensory perception

The process of selecting, interpreting, and organizing sensory information.

Photoreceptor

A sensory receptor that transduces light energy.

Thermoreceptor

A sensory receptor that responds to heat and cold.

Chemoreceptor

A sensory receptor that transduces chemical compounds.

Nociceptor

A sensory receptor consisting of free nerve endings that responds to pain.

Mechanoreceptor

A sensory receptor that transduces mechanical energy such as touch, pressure, vibration, or gravity.

Sclera

The tough, fibrous tissue that forms the white of the eye.

Conjunctiva

The mucous membrane that covers the sclera and lines the inner layer of the eyelid.

Aqueous humor

The watery substance filling the anterior cavity between the cornea and the lens, secreted by ciliary processes.

Vitreous humor

The viscous fluid filling the larger posterior cavity between the lens and the retina.

Accommodation

The ability of the eye to change focus for near or far vision by changing the shape of the lens using the ciliary muscle.

Fovea

The region of sharpest vision in the eye containing the greatest concentration of cones.

Cones

Photoreceptors responsible for color vision and vision during daylight.

Rods

Photoreceptors responsible mainly for vision in dim light or darkness.

Rhodopsin

A visual pigment whose breakdown leads to the transduction of light and transmission of neural signals.

Optic chiasm

The X-shaped structure where optic nerves cross on the floor of the hypothalamus.

Optic disk

The area where the optic nerve passes out of the eyeball, creating a blind spot.

Parts of the Eye (Figure 8-1)

Anatomy diagram illustrating the major internal and external structures of the human eye.

Olfactory epithelium

A specialized tissue lining the upper part of the nasal cavity that contains olfactory receptors.

Taste bud

An oval epithelial capsule containing about 100 taste receptor cells that detect chemical substances dissolved in saliva.

Papillae

Tiny elevations on the tongue that contain taste buds.

Gustation

The sense of taste.

Olfaction

The sense of smell.

Umami

The taste modality corresponding to savoriness.

Substance P

A neurotransmitter released by sensory neurons to stimulate neurons in the spinal cord to transmit pain signals to the brain.

Cerumen

Earwax secreted by ceruminous glands in the ear canal to protect the lining from infection.

Tympanic membrane

The eardrum that separates the external ear from the middle ear and vibrates in response to sound waves.

Eustachian tube

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

Auditory ossicles

Three small interconnected bones in the middle ear (malleus, incus, and stapes) that amplify sound vibrations.

Perilymph

The fluid contained within the bony labyrinth that surrounds the membranous labyrinth of the inner ear.

Endolymph

The fluid contained within the membranous labyrinth of the inner ear.

Organ of Corti

The main sound receptor structure located within the middle canal (cochlear duct) of the inner ear.

Pitch

A quality of sound that depends on the frequency of sound waves, measured in hertz ($\text{Hz}$).