A&P II: Ch. 15-Special Senses Study Guide

Olfactory Neurons

Bipolar sensory neurons located within the olfactory epithelium that feature cilia projecting into the mucous layer.

Action Potential

A rapid rise and fall in voltage or membrane potential across a cellular membrane, initiated by depolarization.

Olfactory Epithelium

A specialized tissue in the nasal cavity containing olfactory neurons responsible for the sense of smell.

Cilia

Hair-like structures on olfactory neurons that detect airborne odorants.

Basal Cells

Cells that replace worn-down olfactory neurons approximately every two months.

Stimulation Mechanism

The process by which airborne odorants dissolve in mucous and bind to receptors on cilia, leading to action potentials.

Olfactory Pathway

The route taken by axons of olfactory neurons as they pass through the cribriform plate to the olfactory bulb.

Olfactory Bulb

A brain structure that processes information about odors, receiving input from olfactory neurons.

Mitral Cells

Neurons in the olfactory bulb that receive synaptic input from olfactory neurons and project along the olfactory tract.

Olfactory Cortex

Part of the frontal lobe that receives primary input from olfactory tracts and is responsible for the conscious perception of smell.

Medial Olfactory Area

Brain region involved in visceral and emotional reactions to odors, interacting with the limbic system.

Intermediate Olfactory Area

Receives input from the olfactory cortex and medial olfactory area, modulating neuronal activity in the olfactory bulb.

Olfactory Adaptation

The process by which the sensitivity to odors decreases with continuous exposure, involving feedback inhibition.

Taste Bud

Oval-shaped sensory structures located on the sides of papillae on the tongue, responsible for taste.

Gustatory Cells

Epithelial cells within taste buds that have microvilli extending through an opening to detect taste.

Microvilli

Tiny hair-like projections on gustatory cells that increase surface area for taste detection.

Papillae

Bumps on the tongue that house taste buds.

Limbic System

A set of brain structures involved in emotion and memory, interacting with the medial olfactory area.

Sour

A major tastant most sensitive on the lateral aspects of the tongue, stimulated by acids (H+).

Salty

A major tastant most sensitive on the tip of the tongue, stimulated by Na+ and other metal ions, craved by humans.

Bitter

A major tastant most sensitive on the posterior aspect of the tongue, with the highest sensitivity threshold to protect against toxic alkaloids.

Sweet

A major tastant most sensitive on the tip of the tongue, stimulated by sugars, carbohydrates, and artificial sweeteners like aspartame.

Umami

A major tastant with scattered sensitivity across the tongue, stimulated by amino acids, craved by humans.

Olfaction

The sense of smell, which heavily influences flavor perception.

Eyebrows

Structures that shade the eyes from sunlight and inhibit sweat from dripping into the eyes.

Eyelids

Structures that protect the eye from foreign objects and lubricate the surface.

Tarsal Plate

A dense connective tissue layer that maintains the shape of the eyelid.

Meibomian Glands

Glands that produce oily sebum at the inner margins of the eyelids to prevent tear evaporation.

Ciliary Glands

Modified sweat glands that open into eyelash follicles.

Caruncle

A small structure located at the medial canthus containing modified sweat and sebaceous glands.

Conjunctiva

A thin, transparent mucous membrane covering the eye.

Palpebral Conjunctiva

The part of the conjunctiva that lines the inner surface of the eyelids.

Bulbar Conjunctiva

The part of the conjunctiva that covers the anterior sclera except over the cornea.

Lacrimal Apparatus

The system that produces and drains tears to cleanse, lubricate, and protect the eye.

Extrinsic Eye Muscles

Six skeletal muscles responsible for precise ocular movement.

Stye

An infection or inflammation of an eyelash follicle or ciliary/sebaceous gland at the eyelid margin.

Conjunctivitis

Inflammation of the conjunctiva, also known as pink eye, caused by infection, allergies, or irritation.

Sclera

The white outer layer of the eye, made of dense collagenous tissue, maintaining eyeball shape and protecting internal structures.

Cornea

The transparent anterior portion of the eye that refracts light and allows it to enter, being avascular.

Choroid

A thin, vascular layer of the eye that delivers oxygen and nutrients to tissues and absorbs excess light.

Ciliary Body

Contains smooth muscles that control lens shape for accommodation and secretes aqueous humor.

Iris

The colored part of the eye that controls the size of the pupil and regulates light entry.

Pigmented Retina

The outer layer of the retina filled with melanin, reducing light scattering and isolating photoreceptors.

Sensory Retina

The inner neural layer of the retina that transduces light energy into nerve action potentials.

Aqueous Humor

A watery fluid produced by ciliary processes that maintains intraocular pressure and provides nutrients.

Vitreous Chamber

The space in the eye filled with vitreous humor, located behind the lens.

Fibrous Tunic

The outer layer of the eye, consisting of the sclera and cornea.

Vascular Tunic

The middle layer of the eye, including the choroid, ciliary body, and iris.

Nervous Tunic

The inner layer of the eye, primarily the retina, responsible for processing visual information.

Anterior Chamber

The space between the cornea and iris filled with aqueous humor.

Posterior Chamber

The space between the iris and lens filled with aqueous humor.

Ciliary Processes

Structures attached to the ciliary body that secrete aqueous humor.

Pupil

The central opening of the iris that regulates light entry into the eye.

Photoreceptors

Cells in the sensory retina (rods and cones) that detect light and convert it into nerve signals.

Accommodation

The process by which the eye adjusts the shape of the lens to focus on near or distant objects.

Canal of Schlemm

The structure that drains aqueous humor from the anterior chamber of the eye.

Melanin

A pigment found in the pigmented retina that helps reduce light scattering.

Suspensory Ligaments

Fibers that connect the ciliary body to the lens, helping to hold the lens in place.

Sphincter Pupillae

Muscle that constricts the pupil in response to parasympathetic input.

Dilator Pupillae

Muscle that dilates the pupil in response to sympathetic input.

Rods

Photoreceptors specialized for low light vision, providing noncolor vision.

Cones

Photoreceptors responsible for color vision and high visual acuity in bright light.

Retina

The light-sensitive layer at the back of the eye containing photoreceptors.

Phototransduction

The process by which light is converted into electrical signals in the retina.

Rhodopsin

The photopigment found in rods, composed of opsin and retinal.

Iodopsin

The photopigment found in cones, responsible for color vision.

Dark Current

The influx of Na+ ions in rod cells that keeps them depolarized in the absence of light.

Hyperpolarization

The process by which rod cells become more negative in response to light, reducing neurotransmitter release.

Glutamate

The inhibitory neurotransmitter released by rod cells in the dark.

Bipolar Cells

Neurons that transmit signals from photoreceptors to ganglion cells.

Ganglion Cells

Neurons that receive input from bipolar cells and send action potentials to the brain.

Fovea Centralis

The area of the retina with the highest concentration of cones, responsible for sharp vision.

Macula Lutea

The region of the retina surrounding the fovea, also rich in cones.

Neuronal Convergence

The phenomenon where multiple rods converge onto a single bipolar cell, enhancing sensitivity.

Cyclic GMP

A molecule that keeps Na+ channels open in the dark, maintaining rod cell depolarization.

Transducin

A G-protein activated by light that plays a key role in phototransduction.

Phosphodiesterase

An enzyme that converts cGMP to GMP, leading to the closure of Na+ channels in light.

Outer Plexiform Layer

The retinal layer where synapses occur between photoreceptors and bipolar cells.

Inner Plexiform Layer

The retinal layer where synapses occur between bipolar cells and ganglion cells.

Nerve Fiber Layer

The layer of the retina containing the axons of ganglion cells that form the optic nerve.

Photoreceptor Layer

The layer of the retina containing the outer and inner segments of rods and cones.

Pigmented Retina

The outermost layer of the retina that absorbs excess light and nourishes photoreceptors.

Action Potential Generation

The process by which neurons generate electrical signals in response to stimuli.

Scotopic Vision

Vision under low light conditions, primarily mediated by rods.

Photopic Vision

Vision under bright light conditions, primarily mediated by cones.

Color Vision

The ability to perceive different colors, primarily facilitated by cone photoreceptors.

Visual Acuity

The clarity or sharpness of vision, best in bright light and associated with cones.

Retina

The light-sensitive layer at the back of the eye where image focusing occurs.

Ciliary Muscles

Muscles that control the shape of the lens for focusing on objects at different distances.

Accommodation

The process of adjusting the lens shape to focus on near objects.

Pupil Constriction

The narrowing of the pupil to increase depth of focus and block stray light.

Convergence

The inward movement of both eyes toward each other to maintain single binocular vision.

Photoreceptors

Cells in the retina (rods and cones) that detect light and convert it into neural signals.

Bipolar Cells

Neurons in the retina that transmit signals from photoreceptors to ganglion cells.

Ganglion Cells

Neurons that receive signals from bipolar cells and send visual information to the brain.

Optic Nerve

The nerve that transmits visual information from the retina to the brain.

Optic Chiasm

The point where optic nerve fibers from the nasal half of each retina cross to the opposite side.

Lateral Geniculate Nucleus

A thalamic structure that relays visual information to the visual cortex.

Visual Cortex

The area in the occipital lobe of the brain responsible for processing visual information.

Visual Field

The entire area that can be seen when the eyes are fixed in one position.