Fundamentals of Anatomy & Physiology - Chapter 17: The Special Senses

A comprehensive set of vocabulary flashcards covering the special senses including olfaction, gustation, vision, equilibrium, and hearing based on Chapter 17 of Fundamentals of Anatomy & Physiology.

Olfaction

The sense of smell.

Odorants

Small airborne organic water-soluble or lipid-soluble substances which stimulate the olfactory receptors.

Olfactory epithelium

A layer in the nasal cavity that covers the inferior surface of the cribriform plate, the superior portion of the perpendicular plate, and the superior nasal conchae.

Lamina propria

The underlying layer of the olfactory epithelium containing areolar tissue, blood vessels, nerves, and olfactory glands.

Olfactory sensory neurons

Highly modified nerve cells whose dendritic bulbs contain dendrites extending into the surrounding mucus.

Basal epithelial cells

Stem cells located in the olfactory epithelium used to frequently replace olfactory neurons.

Generator potential

The result of sodium ion channel opening and olfactory neuron depolarization triggered by the second messenger $cAMP$.

Gustation

The sense of taste, providing information about foods and liquids consumed.

Taste receptor cells

Also known as gustatory epithelial cells, these are found in taste buds on the superior surface of the tongue, pharynx, and larynx.

Filiform papillae

Epithelial projections on the anterior two-thirds of the tongue that provide friction to move food but do not contain taste buds.

Fungiform papillae

Papillae scattered around the tongue with higher concentrations at the tip and sides, containing about five taste buds each.

Vallate papillae

Papillae found in a V-shaped pattern along the posterior margin of the tongue, containing about $100$ taste buds each.

Foliate papillae

Papillae found in folds along the lateral margin of the tongue that contain taste buds.

Taste pore

A narrow opening at the exposed end of the taste bud through which taste hairs extend into surrounding fluid.

Solitary nucleus

The location in the medulla oblongata where sensory afferent fibers from the facial, glossopharyngeal, and vagus nerves synapse.

Umami

A pleasant, savory taste imparted by glutamate and detected by G protein-coupled receptors.

Palpebrae

A continuation of the skin also known as eyelids; blinking keeps the surface of the eye lubricated and clean.

Tarsal glands

Modified sebaceous glands along the inner margin of the eyelid that secrete a lipid-rich product to keep eyelids from sticking together.

Lacrimal caruncle

A mass of soft tissue at the medial angle of the eye containing glands that produce thick secretions.

Conjunctivitis

Inflammation of the conjunctiva, also known as pinkeye, caused by pathogens or irritation.

Lysozyme

An antibacterial enzyme contained within the watery alkaline secretions of the lacrimal gland.

Nasolacrimal duct

The structure that conducts tears from the inferior portion of the lacrimal sac to the nasal cavity.

Aqueous humor

A clear watery fluid similar to $CSF$ that circulates within the anterior cavity of the eye.

Vitreous body

A gelatinous substance found in the large posterior cavity of the eye that stabilizes eye shape.

Sclera

The "white of the eye" made of dense fibrous connective tissue that covers most of the ocular surface.

Cornea

The transparent anterior portion of the fibrous layer that contains no blood vessels and has restricted repair ability.

Iris

A pigmented anterior ring structure containing blood vessels, melanocytes, and pupillary muscles.

Pupil

The central opening of the iris that allows light into the eyeball.

Ciliary zonule

Also known as the suspensory ligament, it is a ring of fibers attaching the lens to the ciliary processes.

Choroid

A vascular layer posterior to the ora serrata whose capillaries deliver oxygen and nutrients to the retina.

Rods

Photoreceptors that are highly sensitive to light but do not discriminate colors, allowing for vision in low light.

Cones

Photoreceptors that provide color vision and sharper images but require more light than rods.

Fovea centralis

The center of the macula and the site of the sharpest color vision.

Optic disc

The origin of the optic nerve on the posterior side of the eyeball, which lacks photoreceptors and is known as the blind spot.

Scleral venous sinus

Also known as the canal of Schlemm, it is the site where aqueous humor is drained at the corneoscleral junction.

Glaucoma

A condition caused by impaired drainage of aqueous humor, leading to increased intra-ocular pressure and potential optic nerve damage.

Crystallins

Proteins within lens fibers that provide clarity and focusing power to the lens.

Cataracts

A loss of transparency in the lens due to injury, $UV$ radiation, drug effects, or aging.

Refraction

The bending of light as it passes from one medium to another.

Accommodation

The automatic adjustment of the eye to provide clear vision by changing the lens shape.

Visual acuity

Clarity of vision compared to a normal standard, where $20/20$ is considered normal.

Myopia

Nearsightedness; occurs if the eyeball is too deep or the lens curvature is too great, causing distant objects to be blurry.

Hyperopia

Farsightedness; occurs if the eyeball is too shallow or the lens is too flat.

Presbyopia

A form of hyperopia in older people caused by the lens losing its elasticity.

Rhodopsin

The visual pigment in rods consisting of the protein opsin and the pigment retinal.

Bleaching

The process following photon absorption where the rhodopsin molecule breaks down into retinal and opsin.

Nyctalopia

Also known as night blindness; it results from a deficiency of vitamin A.

M cells

Ganglion cells that monitor rods and provide information about general form, motion, and shadows in dim lighting.

P cells

Ganglion cells that monitor cones and provide information about edges, fine detail, and color.

Optic chiasm

The location where the two optic nerves reach the diencephalon and undergo a partial crossover of nerve fibers.

Auricle

The outer fleshy cartilaginous portion of the ear, also called the pinna.

Tympanic membrane

A thin, semi-transparent sheet at the end of the auditory canal also known as the eardrum.

Auditory ossicles

Three small bones (malleus, incus, and stapes) that connect the tympanic membrane to the internal ear.

Auditory tube

The structure connecting the middle ear with the nasopharynx to permit equalization of pressure.

Tensor tympani

A muscle that originates in the temporal bone and inserts in the malleus to stiffen the tympanic membrane.

Perilymph

The fluid located between the bony labyrinth and the membranous labyrinth.

Endolymph

The fluid contained within the membranous labyrinth.

Vestibular complex

The combination of the vestibule and semicircular canals where equilibrium sensations are detected.

Ampullary cupula

A gelatinous structure bound to the ampullary crest that bends the stereocilia of hair cells in response to endolymph movement.

Kinocilium

A single large cilium found on the free surface of vestibular hair cells alongside stereocilia.

Otoliths

Densely packed calcium carbonate crystals on the surface of the otolithic membrane in the maculae.

Nystagmus

Trouble controlling eye movements when the body is stationary, often caused by brainstem or internal ear damage.

Hertz ($Hz$)

The unit used to measure sound frequency, equal to the number of cycles per second.

Decibels ($dB$)

The units used to report the intensity or loudness of sound.

Spiral organ

Also known as the organ of Corti, this structure within the cochlear duct contains hair cells that detect sound.

Tectorial membrane

The overlying membrane within the cochlear duct that stereocilia of hair cells contact.