Chapter 17: The Special Senses Study Guide

Vocabulary and terminology based on the Chapter 17 study guide concerning the special senses: olfaction, gustation, vision, hearing, and equilibrium.

Olfaction

The sense of smell, which involves olfactory receptors responding to airborne chemical stimuli.

Olfactory Organs Layers

The two layers comprising these organs are the Olfactory Epithelium and the Lamina Propria.

Mucus

A substance formed from the combination of olfactory gland secretions and water.

Olfactory Reception Initiation

Begins with an odorant binding to a G-coupled protein receptor on the membrane of an olfactory dendrite.

Central Adaptation

The brain’s way of filtering out repetitive smells to make one more sensitive to new, changing, and dangerous ones.

Basal Epithelial Cells

Cells located in the olfactory epithelium that differentiate to form new olfactory receptors.

Gustation

The sense of taste involving gustatory receptors responding to dissolved chemical stimuli.

Filiform Papillae

Lingual papillae that do not have taste buds but provide friction to help move food around the mouth.

Vallate Papillae

Lingual papillae that can have as many as $100$ taste buds per papilla and contain umami taste receptors.

Trigeminal Nerve ($\text{Cranial Nerve V}$)

The nerve containing sensory afferents that send signals about food texture and taste-related sensations.

Umami

A primary taste sensation that detects savory tastes due to free glutamate in certain foods.

Palpebrae

The anatomical term for eyelids, which function to lubricate the outer eye surface when opening and closing.

Lacrimal Caruncle

An eye structure with glands that produce secretions responsible for gritty deposits often found after sleeping.

Chalazion

A condition caused by an infection of the Tarsal glands.

Conjunctiva

The epithelial membrane covering the inner surface of the eyelid and the outer surface of the eyeball.

Conjunctivitis

The clinical term for the condition commonly known as pink eye.

Aqueous Humor

The substance that fills the anterior and posterior chambers of the anterior cavity of the eye.

Vitreous Body

The substance that fills the posterior cavity of the eye.

Sclera

The eye structure commonly known as the "whites of the eyes."

Cornea

The most sensitive part of the eye due to numerous free nerve endings; it has very restrictive self-repairment.

Eye Layers

The three layers are the Outer Fibrous layer, Middle vascular (Uvea) layer, and Inner (Retina) layer.

Iris

The eye structure that contains pupillary muscles responsible for the dilation and constriction of the pupil.

Pigmented Layer

The layer of the retina that functions to prevent light from reflecting through the neural layer.

Rods

Photoreceptors distributed in the periphery of the retina that allow for vision in dimly lit rooms.

Fovea Centralis

The center of the macula, which contains the highest concentration of cones.

Optic Disc ($\text{Cranial Nerve II}$)

The eye structure commonly known as the "blind spot" and the origin of the optic nerve.

Cataracts

Cloudiness in the lens caused by an accumulation of changes to crystallin proteins due to UV radiation, injury, or aging.

Focal Point

The point of intersection of light rays on the retina.

$20/20$ Vision

Clear, normal vision at a distance of $20\text{ft}$, seeing images as they are intended to be seen at that distance.

Emmetropia

The scientific term for normal accommodation or normal vision.

Hyperopia

The scientific term for farsightedness.

Presbyopia

A form of hyperopia caused by the loss of lens elasticity in older individuals.

Rhodopsin

The visual pigment found in rods; it requires Vitamin A for the production of the retinal part.

Nyctalopia

The condition commonly known as "night blindness," often caused by Vitamin A deficiency.

Optic Chiasm

The site where the two optic nerves partially crossover, resulting in each hemisphere receiving visual information from both eyes.

Auricle

The scientific term for the outer fleshy portion of the ear, also known as the Pinna.

Tympanic Membrane

The scientific term for the eardrum.

Cerumen

The common name for the secretion produced by ceruminous glands, also known as earwax.

Otitis Media

A middle ear infection often caused by microorganisms from the nasopharynx entering via the auditory tube.

Auditory Ossicles

The three small ear bones: the Hammer (Malleus), Anvil (Incus), and Stirrup (Stapes).

Saccule and Utricle

A pair of membranous sacs in the vestibule that provide equilibrium sensations.

Otoliths

Ear stones that cover the otolithic membrane and stimulate hair cell processes to send body position information to the brain.

Organ of Corti

The scientific name for the spiral organ located in the cochlea that provides the sense of hearing.