The Special Senses – Notes Flashcards (Chapter 17)

A set of Q&A flashcards covering olfaction, gustation, vision, equilibrium, and hearing concepts from the lecture notes.

What are the two layers that make up the olfactory organ in the nasal cavity?

Olfactory epithelium and lamina propria.

What tissues are contained in the lamina propria beneath the olfactory epithelium?

Areolar tissue, blood vessels, nerves, and olfactory glands that secrete mucus.

What are odorants?

Small airborne substances that stimulate olfactory receptors.

Describe olfactory receptors.

Modified neurons with multiple cilia-shaped dendrites; there are populations with distinct sensitivities.

How are olfactory neurons maintained, and how does age affect them?

Olfactory neurons are replaced frequently from basal cells, but their total number declines with age.

How is odor discrimination encoded in the olfactory system?

Odor components are sorted into different glomeruli and coded by patterns of activity in olfactory bulb glomeruli.

Where are taste receptor cells located?

Gustatory epithelial cells in taste buds on the superior surface of the tongue.

How many basic taste types are there?

Five.

What is gustatory transduction?

Taste receptors convert chemical stimuli into electrical signals interpreted as taste.

What influences gustatory discrimination and sensitivity?

We are more sensitive to unpleasant tastes; sensitivity varies among individuals and is often inherited.

What structures comprise the eye’s accessory structures and their functions?

Eyelids, lacrimal gland, and tears; tears moisturize, reduce friction, remove debris, cleanse, and prevent infection.

What is aqueous humor and how is it managed?

A clear, watery fluid secreted by the ciliary processes, circulating in the anterior chamber and drained via the scleral venous sinus to maintain intraocular pressure.

What is glaucoma?

Impaired drainage of aqueous humor through the scleral venous sinus, causing increased intraocular pressure and optic nerve damage.

What are the three layers of the eyeball and their components?

Fibrous layer (sclera and cornea), vascular layer (pigmented choroid), and retina (pigmented and neural layers).

What are rods and cones, and where are they most densely located?

Rods: highly light-sensitive, peripheral retina; Cones: color vision, dense in the macula with the fovea centralis at the center.

What is the optic disc?

The origin of the optic nerve; called the blind spot because it has no photoreceptors.

What is accommodation in the eye?

Automatic adjustment of the lens to provide clear vision: rounder lens for near objects (ciliary muscle contracts) and flatter lens for distant objects (muscles relax).

What is refraction in the visual system?

Bending of light as it passes between media, mainly by the cornea and lens.

What are the external ear structures?

Auricle (pinna), tympanic membrane, and ceruminous glands.

What are the middle ear’s main components and their connections?

Auditory tube (to nasopharynx) and auditory ossicles: malleus (attached to tympanic membrane), incus (between malleus and stapes), and stapes (attached to the oval window).

What do the tensor tympani and stapedius muscles do?

Tensor tympani pulls on the malleus to stiffen the tympanic membrane; stapedius reduces movement of the stapes at the oval window.

What are the inner ear structures and their fluids?

Bony labyrinth (vestibule, semicircular canals, cochlea) and membranous labyrinth with perilymph (between labyrinths) and endolymph (within membranous labyrinth).

What do the vestibule and its components provide?

Equilibrium sensation via the saccule and utricle.

What do the semicircular canals and ampullae detect?

Equilibrium through rotational movements; ampulla contains hair cells and the ampullary crest with the ampullary cupula.

What is the Organ of Corti and what does it do?

Hair cells on the basilar membrane that detect sound; stereocilia contact the tectorial membrane.

What are the round window and oval window’s roles?

Oval window transmits vibrations from the stapes to the cochlea; round window absorbs acoustic energy to dissipate it.

What are the cochlear compartments and their fluids?

Cochlear duct (scala media) filled with endolymph; scala vestibuli and scala tympani filled with perilymph.

What is the basilar membrane, tectorial membrane, and hair cells’ relationship?

Basilar membrane vibrates in response to sound; hair cells with stereocilia contact the tectorial membrane; bending triggers neural signals via the cochlear nerve.

How is pitch related to the basilar membrane’s location of vibration?

High-frequency sounds vibrate the basilar membrane near the oval window (base); low-frequency sounds travel further toward the apex.

What are otolithic membranes and otoliths?

Otolithic membrane is a gelatinous structure with embedded hair cell stereocilia; otoliths are calcium carbonate crystals on its surface.

What is the function of tears aside from moisture?

Lysozyme-containing tears help protect against infection and cleanse debris.