Chapter 10 – Sensory Physiology (BIOL 241)

Vocabulary flashcards summarizing the key terms and definitions from the Sensory Physiology lecture, covering sensory receptors, taste, smell, equilibrium, hearing, and vision.

Sensory Receptor

Structure that transduces environmental information into action potentials, the common language of the nervous system.

Transduction

Conversion of a stimulus into an electrical signal (action potential) in the nervous system.

Modality

Form of sensory information (e.g., light, sound, pressure) detected by a specific receptor type.

Chemoreceptor

Receptor that detects chemical stimuli.

Photoreceptor

Receptor that transduces light energy.

Thermoreceptor

Receptor that responds to temperature changes.

Mechanoreceptor

Receptor activated by deformation of its cell membrane (e.g., touch, pressure).

Nociceptor

Receptor that responds to intense stimuli by signaling pain.

Proprioceptor

Receptor that provides positional information about body parts.

General (Cutaneous) Receptor

Receptor located near an epithelial surface; detects touch, pressure, temperature, or pain.

Special Sense Receptor

Receptor that is part of a dedicated sensory organ (e.g., eye, ear).

Tonic Receptor

Receptor that fires at a constant rate as long as a stimulus is present; exhibits little adaptation (e.g., pain receptors).

Phasic Receptor

Receptor that shows a burst of activity and then rapidly adapts to constant stimulation (e.g., smell, touch).

Law of Specific Nerve Energies

Stimulation of a sensory fiber evokes only the sensation of its specific modality.

Adequate Stimulus

The normal stimulus type that requires the least energy to activate a receptor.

Generator Potential

Graded depolarization in a sensory receptor analogous to an EPSP; its amplitude is proportional to stimulus intensity.

Exteroceptor

Receptor that responds to chemicals or stimuli in the external environment (e.g., taste buds, olfactory receptors).

Interoceptor

Receptor that monitors chemical changes inside the body.

Gustation (Taste)

Sense that detects sweet, sour, salty, bitter, and umami stimuli.

Taste Bud

Cluster of 50–100 modified epithelial taste receptor cells.

Umami

Taste sensation produced by amino acids (notably glutamate).

Salty Taste Mechanism

Ions enter through channels without using receptors; leads to depolarization.

Sour Taste Mechanism

Protons (H⁺) enter or block channels, causing depolarization; no receptor binding.

Sweet Taste Mechanism

Sugars bind to membrane receptors and activate G-proteins to produce depolarization.

Bitter Taste Mechanism

Alkaloids bind to membrane receptors and act via G-proteins to depolarize the cell.

Olfactory Epithelium

Patch of tissue at the roof of the nasal cavity housing smell receptors.

Olfactory Receptor Cell

Bipolar neuron whose axon projects to the olfactory bulb to convey smell information.

Basal Cell (Olfaction)

Stem cell in olfactory epithelium that generates new receptor cells every 1–2 months.

Supporting Cell (Olfaction)

Non-sensory cell containing detoxifying enzymes; supports olfactory receptor neurons.

Vestibular Apparatus

Inner-ear structure providing the sense of equilibrium and orientation to gravity.

Otolith Organ

Either the utricle or saccule; detects linear acceleration.

Semicircular Canal

One of three ducts oriented in different planes that detect rotational (angular) acceleration.

Endolymph

Potassium-rich fluid filling the membranous labyrinth of the inner ear.

Kinocilium

Single large cilium on a hair cell; bending toward or away alters cell polarization.

Macula (Ear)

Sensory patch in utricle and saccule containing hair cells for linear acceleration.

Otoliths

Calcium carbonate crystals within the otolithic membrane that add inertia to hair cells.

Crista Ampullaris

Sensory region in the base of each semicircular duct containing hair cells for rotational detection.

Cupula

Gelatinous structure in the crista ampullaris in which hair cell stereocilia are embedded.

Frequency (Sound)

Number of wave cycles per second, measured in hertz (Hz).

Pitch

Perception directly related to sound frequency.

Intensity (Sound)

Loudness; directly related to the amplitude of sound waves.

Decibel (dB)

Unit measuring sound intensity.

Accommodation (Eye)

Ability of the eye to maintain a focused image on the retina as viewing distance changes via ciliary muscle contraction.

Visual Acuity

Sharpness of vision; depends on the eye’s resolving power to distinguish fine detail.

Myopia

Nearsightedness; image focuses in front of the retina because the eyeball is too long.

Hyperopia

Farsightedness; image focuses behind the retina because the eyeball is too short.

Astigmatism

Uneven lens or cornea curvature causing uneven light refraction and focus.

Retina

Multilayered neural tissue at the back of the eye containing photoreceptors, neurons, and pigmented epithelium.

Photoreceptors (Rods & Cones)

Light-sensitive cells; rods are for low-light vision, cones for color and sharp vision.

Rhodopsin

Visual pigment in rods; splits into retinal and opsin during the bleaching reaction when exposed to light.

Bleaching Reaction

Light-induced dissociation of rhodopsin leading to phototransduction events.

Dark Current

Continuous Na⁺ influx in photoreceptors under dark conditions causing depolarization.

cGMP (in Vision)

Second messenger that keeps Na⁺ channels open in the dark; light converts cGMP to GMP, closing channels.