Anatomy Ch 17-Special Senses

Colds and allergies

During _______ and ______, loss of taste is due to olfactory receptors not being active and taste only occurs from the tongue.

Albinos

Melanin absorbs light rays preventing reflection and scattering of light with the eyeball. ________ lack melanin and must wear sunglasses due to moderate light appearing bright.

Central retinal

_____ _____ artery and vein in the same bundle leaving at the optic disc. Nourishes and drains blood from the retina.

visible light

_____ _____ occurs in waves having a wavelength of 400-700 nm.

Nasal

_____ or central half of the vision field = area toward the nose or midline of the body. Axons of ganglion cells in the _______ half of each retina extend to the thalamus on the opposite side. Fibers from ____ 1/2 of each retina cross in optic chiasm (same word)

external ear

______ ______ collects sound waves and channels them inward it consist of the auricle (pinna).

Auricle (pinna)

a flap of skin over elastic cartilage, shaped like the flared end of a trumpet, that is designed to efficiently collect sound waves. It is attached to your head with ligament

Otoliths

a layer of dense calcium carbonate crystals (stone) that extend over the surface of the otolithic membrane.

otoscope

a lighted, magnifying instrument for viewing EAC and eardrum.

binocular vision

is the medial movement of the two eyeballs so that both are directed toward the object being viewed. Both eyes look at the same object at the same time.

hyposmia

is the reduced ability to smell. it affects about half of those over age 65 and 75% of those over 80. It can be caused by neurological changes, drugs, or the effects of smoking.

semicircular canals

lay superior and posterior to the vestibule and are named by orientation: anterior, posterior, and lateral. They are arranged at approximate right angles in and X-Y-Z, 3-D graphical view. Anterior and posterior are oriented vertically. The lateral is oriented horizontally.

Presbyopia

lens loses elasticity and thus its ability to focus.

tympanic membrane

eardrum. Thin partition between auditory canal & middle ear. Composed of connective tissue (collagen, elastic fibers, and fibroblasts) overlaid with simple cuboidal epithelium.

cerumen

earwax. _______ and hairs in the canal protect outer ear from foreign objects, water, and insects. Wax is overproduced by some individuals resulting in impacted ________, removed by periodic irrigation or medical personnel.

Cochlear implants

electronic implants with a microphone, microprocessor and electrodes that translate sound into electric stimulation of the vestibulocochlear nerve. Artifically induced nerve signals go to the brains and provide a "crude" representation of sounds.

Horizontal cells

enhance contrast in the visual scene by inhibiting bipolar cells lateral to the excited rods and cones, and assists in the differentiation of various colors.

Cupula

mass of gelatinous material covering the crista.

emmetropic eye

normal vision; can refract light from an object 20 ft. away so that a clear image forms on the retina.

stapes

stirrup, the footplate of the stapes attaches to the oval window. The round window (for pressure equalization) covered by a secondary tympanic membrane lays just below the oval window.

near point

the _____ ______ of vision is the minimum (closest) distance from the eye that an object can be clearly focused with maximum effort. As you age the distance becomes greater for this type of vision.

transduction

the conversion of stimulus energy into electrical potential in a sensory receptor.

cornea

transparent coat over the colored iris which helps focus light onto the retina. It is composed from outside, inward of: o Non-keratinized stratified squamous epithelium Collagen fibers and fibroblasts Simple squamous epithelium

anterior chamber

chamber of the anterior cavity, it is the space between the cornea and iris.

Posterior chamber

chamber of the anterior cavity, it is the space between the iris and the lens.

ganglion cell layer

from the inner synaptic layer this layer receives impulses then the axons of ganglion cells form the optic (II) nerve leaving the eyeball at the optic disc.

Meniere's Syndrome

is a malfunction of the inner ear that may cause deafness and loss of equilibrium. Caused by excessive endolymph production and enlargement of the membranous labyrinth.

Glaucoma

is abnormally high intraocular pressure, due to a buildup of aqueous humor inside the eyeball, which destroys neurons of the retina. It is the second most common cause of blindness (after cataracts), especially in the elderly.

light adaptation

is adjustments made by our eyes when we move from the dark into light. One adjustment is the constriction of the pupil.

Otitis media

is an acute infection of the middle ear, primarily by bacteria. It is characterized by pain, malaise, fever, and reddening and outward bulging of the eardrum, which may rupture unless prompt treatment is given.

perilymph

is chemically similar to cerebrospinal fluid and surrounds and protects the bony labyrinth.

glaucoma

is excessive intraocular pressure. It is caused by a problem with drainage of the aqueous humor and may produce degeneration of the retina and blindness.

dark adaptation

is the adjustment made by our eyes when we move from bright light into darkness. In the dark, light sensitivity increases as photopigments regenerate.

adaptation

is the decreasing sensitivity to an odor and it is rapid being 50% after 1 second and complete desensitivity to certain odors after 1 minute.

palpebral fissure

is the gap between the eyelids.

Internal ear

houses the receptors for hearing and equilibrium. Also called the labyrinth because of its' complicated series of canals.

pupil

is the hole in the center of the iris. It appears black because you see through this hole to the heavily pigmented back of the eye (choroid and retinal layers).

Anatomy

study of the structures in the body.

helix

the rim of the auricle.

gustatory receptor cells

the working cell in the taste bud. taste receptor cells located in the tongue papillae

vestibulocochlear nerve

(Cranial Nerve VIII) branches into vestibular branch and cochlear branch to serve all structures in the vestibule and cochlea. The vestibular branch divides to the ampullary nerves (serves ampulla of each duct), utricular nerve (serves utricle) and saccular nerve (serves saccule)

tarsal glands

(Meibomian glands) for lubricant between lids; keep from sticking together.

opsin

(a glycoprotein) is the base of the pigment. There are four different . Rhodopsin is the _____ in the rod. There are three different _____s in the cones. Variations in the structure of three _____s is responsible for how cones absorb different colors (wavelengths) of light (same word all blanks)

lacrimal gland

(almond-size) are structures that each produce and drain off lacrimal fluid or tears at a rate of 1 mL/day through 6-12 lacrimal ducts.

constrictor pupillae

(circular muscle fibers) contract in bright light to shrink pupil. They are innervated by parasympathetic nerve fibers.

retinal

(derivative of vit. A) is the light-absorbing part of all visual photopigments.

cones

Cone-shaped photoreceptors that allow us to see color in brighter light, For color vision and sharpness of vision (high visual acuity) in bright light, Densely concentrated on the fovea, as discussed above. 6 million cones on each retina. "discs are formed in folded pleated fashion"

lacrimal fluid

Fluid that spreads medially across eyeball during blinking, lubricating, moistening and protecting is called? It is made up of water, salts, mucus, and lysozyme.

cerebral cortex, limbic

Impulses for smell propagate or make their way to the _______ ______ and the ______ system. These odors and tastes can evoke strong emotional responses and memories of the brain.

opthalmoscope

Instrument that shines light into the eye and allowing one to peer through the pupil and observe a magnified image of the retina, its blood vessels and the optic (II) nerve.

oval window

Is at the boundary between the middle ear and inner ear., causing vibrations to pass into a coiled, fluid filled tube, known as the Cochlea.

umami

Japanese scientists reported and refers to a "meaty" or "savory" flavor which is believed to arise from taste receptors that are stimulated by monosodium glutamate or MSG which occurs naturally in some foods and is added as flavor enhancer.

papillae

Taste buds occur on elevated areas on the tongue called ______. The three types of ____with taste buds are: vallate papillae, fungiform papillae, and folate papillae

contraction

________ decreases tension on suspensory ligaments and the lens becomes more spherical (convex), increasing its focusing power. This allows focus on near objects (part of accommodation)

lysosyme

a protective bacteriocidal enzyme in the lacrimal fluid along with water, salts, and mucus.

scala vestibuli

first channel in the cochlea which ends at the oval window. It is part of the bony labyrinth and contains perilymph.

Presbycusis

hearing loss due to damaged or loss of hair cells in the organ of Corti

obicularis oculi

muscle for opening and closing eyelids, blinking.

thresholds

point of taste detection, can vary among the primary taste: We are most sensitive to bitter, and least sensitive to salty and sweet.

autonomic reflexes

pupil diameter (dilation) is regulated by the response of ______ _______ to light levels.

static equilibrium

refers to the maintenance of the position of the body (mainly the head) relative to the force of gravity. Receptors detect actions such as tilting the head and linear acceleration or deceleration (speeding up or slowing down), like in an elevator or a car.

Physiology

science that deals with the functions of an organism and all its structures

scala tympani

second channel in the cochlea which ends at the round window. It is part of the bony labyrinth and contains perilymph.

neural layer

second layer of the neural pathway, a multilayered outgrowth of the brain follows neural path photoreceptor layer, ganglion layer forming ganglion cells from the optic II nerve.

Anterior Semicircular Canal

semicircular duct that responds to head flexion and extension. (as in nodding, or saying yes)

Lateral Semicircular Canal

semicircular duct that responds to horizontal rotation (as in shaking your head "no")

Crista

small elevation in the ampulla with receptor hair cells and supporting cells. This is the primary sense organ for dynamic equilibrium.

macula

small thickened region and are found within the walls of the otolithic organs and are the receptors for equilibrium, These Provide info on position of head in space and are essential for proper posture and balance. Also detect acceleration and deceleration.

decibels

sound is measured in units called what?

photoreceptors

specialized cells that begin the process by which light rays are converted to nerve impulses to the brain. Two types with different shapes: rods and cones.

100-3,000

speech range of hearing is ______-______ hertz

Ophthalmology

study of the science dealing with the eyes and their disorders.

supporting cells of taste

surround and support about 50 gustatory receptor cells per taste bud.

1 inch

the adult eyeball is _____ in diameter, 1/6 exposed, 5/6 protected in the orbit.

macula lutea

the exact center of the posterior portion of the retina, corresponding to the visual axis of the eye.

olfactory transduction

this occurs when an odor stimulates and olfactory receptor resulting in the generation of electrical potential, occurring in the olfactory hair.

Physiology of Hair Cells

• Hair cells convert mechanical deformation (stimulus) into electrical signals (receptor potential) • As microvilli are bent, mechanically-gated channels in the membrane let in K+ ions • This depolarization spreads and causes voltage-gated Ca+2 channels at the base of the cell to open • This triggers the release of neurotransmitter onto the first order neuron. The more neurotransmitter, the more nerve impulses are sent to the brain. • Differences in "heard" pitch are related to differences in the width and stiffness of the basilar membrane. • Due to these differences, sound waves of various frequencies cause certain regions of the basilar membrane to vibrate more intensely than other regions. The membrane is stiffer at the oval window end more flexible toward the apex at the helicotrema. Each segment of the basilar memebrane is "tuned" for a particular pitch. This varies from high-frequency (high-pitch) sounds near 20,000 Hz maximally vibrating the membrane near the oval window, to low pitch sounds vibrating the area near the helicotrema

Intensity

• The volume of a sound is its ________. This is the size or amplitude of the vibrating wave. The greater the _______, the louder the sound.

anterior cavity

1) __________: the space anterior to the lens has two chambers: anterior and posterior chambers.

olfactory epithelium

A mucous membrane at the top of the nasal cavity; contains the olfactory receptor neurons that respond to airborne molecules called odorants.

Pitch

A tone's experienced highness or lowness; depends on frequency.

binocular visual field

Because our eyes are anterior on the head, the left and right visual fields overlap. This is our ______________________.

60, 140, 90

Conversation = ___ decibels; pain above ____ decibels; OSHA requires hearing protection above ____decibels.

Stimulus, receptor potential

Hair cells convert mechanical drormation (_______) into electrical signals (_________)

utricle and saccule

In the vestibule are small sacs called ______ ("little bag") & ________("little sac") connected by a duct.

color blindness

Inability to distinguish between certain colors, An inherited trait, Absence of certain cone photopigments. Most common type red-green; red or green cones are missing; person can't tell red from green. More common in males.

reflected

Our eyes see the ______ light from an object. If blue is absorbed and orange is ______. we see orange. White objects see ______ all wavelengths of visible light and black objects absorb all wavelengths. (1 word)

fovea centralis

The ______ ________ is the area of highest visual acuity or resolution (=sharpness of vision). We move our heads to place the image we are looking for on the ______ _________. (same words)

sclera

The ______ is a hard layer of dense connective tissue. It is the "white" of the eye. o Covers the entire eyeball (except cornea). Its' tough, hard composition gives rigidity, shape, and support to the eye and an ideal attachment for the extrinsic eye muscles. Posteriorly pierced by optic nerve (Cranial Nerve II)

vestibular branch

The _______ ______ divides to the ampullary nerves (serves ampulla of each duct), utricular nerve (serves utricle) and saccular nerve (serves saccule) Branch of vestibulocochlear nerve.

Left, right

________occipital lobe sees right 1/2 of the world and the _____ occipital lobe sees the left 1/2 of the world.(2 words)

astigmatism

an irregular curvature of cornea or lens causing partially blurred vision.

equilibrium

balance

Cataract

is a loss of transparency of the lens that can lead to blindness.

conduction deafness

is caused by impairment of the external and middle ear mechanisms for transmitting the sound to the cochlea. Causes: otosclerosis, deposition of new bone around oval window, impacted cerumen, eardrum damage, aging.

high frequency, base

(high-pitch) tone causes the basilar membrane to vibrate near the ______ of the cochlea (where it is stiff and narrow)

Folate Papillae

(leaflike): located in small trenches on lateral edge of tongue; most of their taste buds degenerate after childhood.

low frequency, apex

(low-pitch) tone causes the basilar membrane to vibrate near the______of the cochlea where it is flexible and wide.

iris

(means rainbow) colored portion of the eyeball, functions to regulate the amount of light entering the eyeball through the pupil. shaped like a flat donut and lays between the cornea and lens. contains melanin-producing melanocytes, the amount determining eye color, and also contains circular and radial muscle fibers attached to ciliary processes.

fungiform papillae

(mushroom-like): mushroom-shaped papillae containing 5 taste buds each that and scattered over the entire surface of the tongue.

sensorineural deafness

(nerve deafness) is caused by either impairment of hair cells in the cochlea or damage of the cochlear branch of the vestibulocochlear (VIII) nerve. Causes: atherosclerosis (reduced blood supplies to ear), repeated exposure to loud noise destroying hair cells, and certain drugs.

dilator pupillae

(radial muscle fibers) contract in dim light to enlarge pupil. They are innervated by sympathetic nerve fibers.

lacrimal puncta

(small openings) tears drain through these from the lacrimal gland, then they travel through lacrimal canals to the lacrimal sac and hence to the nasal cavity.

filiform papillae

(threadlike papillae): contain tactile receptors but no taste buds. Increase friction during chewing helping to move food into the oral cavity.

middle ear

(tympanic cavity) A small, air-filled cavity in the temporal bone lined by epithelium. Functions to conveys sound vibrations to the oval window. Separated from external ear by eardrum, and from internal ear by oval and round windows. Includes, Malleus, Incus, Stapes, and eustacian tube

vallate papillae

(wall-like; circumvallate): form an inverted V-shaped row at back of tongue. Consists of about 12 papillae each with 100-300 taste buds.

Auditory Pathway

-The cochlear branch of the vestibulocochlear (VIII) nerve carries impulses to the cochlear nuclei in the medulla oblongata -Within the medulla, the impulses are sent on to the lateral lemniscus in thetracts (on both sides) -Differences in the arrival time of the impulses from the right and left ears, allows us to locate the source of a sound as to left and right. -Fibers then ascend to the inferior colliculus of the midbrain, then to the medial geniculate nucleus thalamus, then to the auditory area of the temporal lobe at the primary auditory area in the cerebral cortex (area 41 and 42). At this place in the brain, sound is analyzed allowing response as needed.

equilibrium pathway

1 When you move, fluid in the canal tends to stay in place, thus bending the cupula and bending hair cells. 2. The bending of hair bundles produces receptor potentials leading to nerve impulses that pass along the vestibular branch of the vestibulocochlear nerve. 3. Nerve signals to the brain are generated which indicate direction of head rotation. 4. The Pathway to the CNS is similar to hearing, entering the medulla. However, some fibers enter directly into the cerebellum. These fibers connect to 5. Cranial nerves of the eye, head, and neck movements (III, IV, VI, XI). Vestibulospinal tract that adjust postural skeletal muscles in response to head movement. Since the cerebellum is updated continuously, the motor areas of the cerebral cortex can adjust to maintain balance.

gustatory pathway

1. Dissolved tastant contacts gustatory hairs and taste transduction begins. 2. Receptor potential results in neurotransmitter release in the gustatory receptor cells. 3. Neurotransmitter molecules trigger nerve impulses in the 1st order sensory neurons 4. Different tastes arise from activation of different groups of 1st order gustatory neurons. 5. Three cranial nerves contain axons of the 1st order gustatory neurons (Fig. 17.3e) a. facial (VII) nerve serves taste buds in the anterior 2/3 of the tongue b. glossopharyngeal (IX) nerve serves taste buds in the posterior 1/3 or tongue c. vagus (X) nerve serves taste buds in the throat and epiglottis 6. These cranial nerves carry taste impulses to the gustatory nucleus in the medulla oblongata. 7. From the medulla, some axons carry taste impulses to the limbic system and the hypothalamus and others to the thalamus. 8. Taste signals from thalamus to primary gustatory area on the parietal lobe of the cerebral cortex give rise to the conscious perception of taste......ummm that tastes good!

olfactory pathway

1. Odorants bind to the olfactory receptor hairs causing chemical reactions that opens the sodium (Na+) channel from the extracellular fluid to the intracellular fluid (cytosol) 2. As sodium enters the cytosol, a depolarizing generator potential occurs 3. Depolarization of the olfactory receptor cell membrane occurs. 4. A nerve impulse is triggered 5. On each side of the nose, bundles of axons of olfactory receptors pass through one of about 20 olfactory foramina (openings) through the cribiform plate. (40 total) Collectively, they are the right and left olfactory (I) one nerves. 6. These terminate in the brain and synapse with dendrites of olfactory bulb neurons in the paired masses of gray matter called the olfactory bulbs (17.1b). 7. Axons of the olfactory bulb neurons collectively form the olfactory tract (17.1b). Some of these axons go to the Primary olfactory are of the cerebral cortex (17.1d) where the conscious awareness of smell begins. Some of these axons go to the limbic system and hypothalamus, where emotion and memory-evoked responses to odors originate. 8. Pathways to the frontal lobe from the primary olfactory area are also present for odor identification.

pathway of hearing

1. The auricle directs sound waves into the external auditory canal 2. Sound waves strike the tympanic membrane, causing it to vibrate back and forth. 3. This vibration is conducted from the tympanic membrane through central area (malleus, incus, then stapes) 4. The stapes, on the far end, moves back and forth, pushing the membrane of oval window in & out. 5. Movement of the oval window causes fluid pressure waves in perilymph of the scala vestibuli of the cochlea. 6. Pressure waves in the scala vestibuli are transmitted to scala tympani at the helicotrema and eventually to the round window which bulges outward into the middle ear. 7. As the pressure waves deform the wall of the two scalas, they push the vestibular membrane back and forth and increase and decrease the pressure of the endolymph inside the cochlear duct. 8. Pressure changes of the endolymph vibrate the basilar membrane moving the hair cells of the spiral organ against the tectorial membrane. This leads to bending hair cell stereocilia, producing receptor potentials leading to the generation of nerve impulses to the brain.

Otosclerosis

A condition where there is a spongy overgrowth of spongy bone over the oval window that immobilizes the stapes. Stops transmission of sound to inner ear and leads to conductive hearing loss.

night blindness or nyctalopia

A deficiency in rhodopsin which may cause ________ ______ The person has the inability to make the normal amount of rhodopsin. Possibly due to a deficiency of vitamin A which inhibits the ability to see under low light levels.

cerebral cortex

A large portion of the _____ _____ is dedicated to processing visual information.

helicotrema

An opening at the apical end of the cochlea connecting the scala vestibule with the scala tympani.

microvilli

As __________ are bent, mechanically-gated channels in the membrane let in K+ ions. (Physiology of hair cells).

visual pathway in retina

In the retina, visual inputs are enhanced, modified, or discarded. 1. Receptor potentials arise in the outer segments of rods and cones 2. Receptor potentials spread through the inner segments to the synaptic terminals 3. Neurotransmitter molecules released by rods and cones induce (cause) graded potentials in bipolar cells and horizontal cells. 4. Many rods synapse with a single bipolar cell in outer synaptic layer. Light stimulates rods and excites bipolar cells 5. One cone usually synapses with a single bipolar cell. Light excites or inhibits cone bipolar cells. 6. Convergence of many rods onto one bipolar cell increases sensitivity to light; slightly blurry image results. Cone vision is sharper with one-to-one synapses, cones to bipolar cells. Ultimately, 126 million photoreceptors in each eye converge on 1 million ganglion cells. 7. Horizontal cells: (1) enhance contrasts in the visual scene by inhibiting bipolar cells lateral to the excited rods and cones. (2) assists in the differentiation of various colors. 8. Amacrine cells: excite bipolar cells if level of illmination of the retina changes. 9. Finally, these bipolar or amacrine cells transmit excitatory signals to ganglion cells which depolarize and initiate nerve impulses.

inferior colliculus

Located in the Midbrain. Processing of auditory information, bringing the source of sounds in our environment to our attention and locating them relative to our position.

hair cells

Loud noises damage _____ _____ of the cochlea. (jets, gunshots, lawnmowers, etc.)

primary auditory area

Part of the temporal lobe in which auditory information is first registered.

rods

Rod-shaped photoreceptors and formed of "discs stacked like coins" that allow us to see in dim light, such as moonlight, Allow us to discriminate between different shades of dark and light (gray), Permit us to see shapes and movement, Absent from fovea and macula lutea. Increased density toward periphery of retina.120 million rods per retina.

taste buds

Structures on the tongue that contain the receptor cells for taste, there about 10,000 in the oral area, mainly located on the dorsal-top-side of the tongue, but also on soft palate, the posterior portion of the roof of the mouth, the pharynx (throat), and the epiglottis (flap over the voice box), oval body containing 3 kinds of epithelial cells

hair cells, supporting cells

The Macula consist of two kinds of cells _____ ______ are the sensory organs of the macula; 40-80 stereocilia of graded height, plus one kinocilium. Hair bundle collectively, stereocilia and kinocilium. Kinocilium a conventional cilium anchored firmly to the basal body and extending beyond the longest sterocilium, and _________ cells

sound waves, equilibrium

The ear is a receptor for _____ ________and also contains receptors for _________ (balance).

ear

The _________transduces sound vibrations with amplitudes as small as the diameter of an atom of gold (0.3nm) into electrical signals - and does it 1,000 times faster than photoreceptors can respond to light.

Otoacoustic emissions

The cochlea can produce sounds and they are called ________ _______? They are caused by vibrations of the outer hair cells that occur in response to sound waves and to signals from motor neurons. These vibrations travel back toward the eardrum and can be recorded by a sensitive microphone. Detection of these is easy and non-invasive and used to test newborns for hearing defects. The purpose of these is to increase auditory sensitivity.

Homeostasis

The condition in which the body's internal environment remains relatively constant within physiological limits.

image formation

The image formed on the retina is inverted (upside down) and reversed, left to right. Yet we see the image as it is! The brain learns at an early age learns to correct the image.

round window

The membrane that relieves pressure from the vibrating waves in the cochlear fluid. Covered by a secondary tympanic membrane and lays just below the oval window.

sclera venous sinus or canal of Schlemm

The opening in the white of the eye at the junction of cornea and sclera is called the ____ ____ sinus or _____ __ _____. Into this sinus, a fluid called aqueous humor drains from the eye to the bloodstream.

spiral organ or organ of corti

The organ of hearing, consisting of supporting cells and hair cells that rest on basilar membrane & extend into endolymph of cochlear duct. • 16,000 hair cells the receptors for hearing, each w/ 30-100 stereocilia (microvilli) - of graded height. At basal end, hair cells synapse with 1st order sensory neurons whose cell body is in the spiral ganglion.

viewing point

The retina is a very important ________ _______ for pathological changes, e.g. hypertension, diabetes, cataracts, etc.

sensory organs

The special senses _______ _______ with receptors. These allow one to smell, taste, see, hear and maintain equilibrium or balance.

Dynamic equilibrium

The three semicircular ducts function in ________ ____________. Two vertical ducts are anterior and posterior semicircular ducts. One horizontal duct is the lateral semicircular duct. The position of the 3 permits detection of rotational acceleration or decelleration. They give a 3-D sensitivity.

Cribiform plate

Thin, medial portion of the ethmoid bone of the skull.

supporting cells, gustatory receptor cells, and basal cells

Three kinds of epithelial cells in the taste bud.

otolith

What are calcium carbonate crystals that assist the movement of the gelatinous mass through gravitational force called in Dynamic Equilibrium?

refraction

______ of Light Rays: the bending of light rays as they pass from one substance (air) into another substance (cornea) with a different density. Light is refracted by the cornea and the lens so that the rays fall upon the retina. In the eye, light is refracted by the anterior and posterior surfaces of the cornea and lens. 75% of refraction is done by cornea and 25% by the lens. Light rays coming in from about 20 feet or more are nearly parallel and only need to be bent enough to focus on the retina.

Otolithic organs

______ organs; saccule and uticle; function in static equilibrium.

macular degeneration

_______ ____ is a degeneration of the retina in older (+50) folks. Keep peripheral vision but lose ability to see straight ahead due to degeneration of the macular lutea.

Odors

_______ drift up from mouth and into the nasal cavity and stimulate your olfactory receptors and the tactile (feel) of that food rolling around in your mouth---all are a part of taste.

Bleaching

_______ occurs. After a minute, trans-retinal separtes from opsin becoming colorless. Step 2 of vision transduction.

bleaching and regeneration

________ and___________of photopigments accounts for much but not all of sensitivity change in light and dark adaptation.

Regeneration

________ converts trans-retinal back to cis-retinal. _________ completion. When darkness returns, cis-retinal binds to opsin reforming a functional photopigment. The pigment epithelium near the photoreceptors contains Vitamin A to help the regeneration process. Cone photopigments regenerate much quicker than rods, taking only in 90 seconds. Rods -- Rhodopsin photopigments regenerate by only ½ in about 5 minutes, fully in 30-40 minutes.

cochlea, modiolus

________ is a bony, spiral canal that resembles a snail shell, making almost three turns around a central bony core called the ________. (2 words)

Ampulla

________ is the dilated portion at the base of each of the three semicircular ducts.

temporal

________ or peripheral half of the vision field = area toward the side of the body, right or left. Axons of ganglion cells in the _________half of each retina extend to the thalamus on the same side. (same word)

receptor cells

_________ synapse with dendrites of first order neurons to begin the gustatory pathway. These dendrites are branched and contact many receptor cells in many taste buds.

isomerization

__________ occurs. Light causes cis-retinal to straighten to trans-retinal. Details: In darkness, retinal has a bent shape called cis-retinal snugly fit into the opsin portion of the pigment. Cis-retinal absorbs a photon of light and, in a process called __________, straightens out to from to trans-retinal. A series of chemical changes lead to production of a receptor potential. (same word) Step 1 of vision transduction.

constriction

__________ of the pupil occurs by contraction of the pupillae muscle (circular muscles of the iris) 1. Regulate bright light from entering eye, as stated earlier. 2. Accommodation it prevents light from entering the edges of the lens, as this would blur image.

frequency

___________ of the vibration is pitch-higher frequency, higher pitch.

convergence

__________is necessary so that light from the object strikes both retinas at the same point. The extrinsic eye muscles coordinate this action.

relaxation

_______increases tension on suspensory ligaments (zonal fibers) and the lens flattens. This allows focus on far objects. (part of accommodation)

lateral lemniscus

a band of fibers running rostrally through the medulla and pons; carries fibers of the auditory system.

cochlear duct

a channel in the cochlea (scala media) is a continuation of the membranous labyrinth into the cochlea. For this reason, it contains endolymph. It's the third channel between wings of Y. Scala vestibuli and scala tympani are separated by this, their entire length except at the apex of the cochlea where they join at the helicotrema.

ciliary muscles

a circular band of smooth muscle which contracts or relaxes to adjust tightness of suspensory ligaments attached to the lens. This altering of lens shape focuses the image for you - near or far. (ciliary body)

presbyopia

a condition in which the lens loses elasticity and thus its ability to focus.

external auditory canal

a curved tube about an inch long leading to eardrum.

Tinnitis

a ringing, roaring or clicking in the ears.

membranous labyrinth

a series of epithelial sacs and tubes housed in the bony labyrinth, and with same general form, which form the organs or hearing and equilibrium. Inside filled with endolymph. Includes utricle and saccule.

deafness

a significant or total hearing loss.

fovea

a small depression located in the center of the macula lutea where the sharpest vision occurs. Contains only cones (color vision).

Concave

a surface curves inward, like the inside of a hollow ball, and will refract incoming light rays away from each other.

convex

a surface that curves outward, like a ball, that lens will refract incoming light rays toward each other till they intersect (in vision, on the retina)

conjuctiva

a thin mucous membrane that lines the inner aspect of the eyelids and passes onto the anterior surface of the eyeball.

vitreous body

a transparent jelly-like substance within vitreous chamber that holds the retina flush up against the choroid giving an even surface capable of receiving clear images. o Not renewed -- same material since embryonic development.

hyperacusia

abnormally sensitive hearing, it is associated with stapedius muscle.

Optic disc

also call the blind spot, since no images can be formed here, the impulses then travel to thalamus and the primary visual cortex. this is where optic nerve exits eyeball.

eyelids

also called palpebrae, they shade eyes during sleep, protect eyes from excess light and objects, and lubricate the eyeball with secretions.

Stem cell

an unspecialized cell that can divide and give rise to a specialized cell.

ciliary body

anterior part of the vascular tunic; also dark brown due to melanocytes/melanin Contain ciliary processes.

incus

anvil, the middle bone, which articulates with the head of the stapes

eyebrows

arch up over the entire eye ball area, these along with eyelashes protect the eye from foreign objects, perspiration, and direct rays of sunlight

sound waves

are alternating high and low pressure regions traveling in the same direction through some medium such as air and originate from a vibrating object.

photopigments

are colored proteins that change structurally when they absorb light, respond to light in a cyclical process. Rods contains photopigment rhodopsisn. Cones contain 3 different cone photopigments, one in each of the three types of cones. Color vision comes from this.

vitreal floaters

are debris that can form in old age that make specs form in the image as they float around in the substance.

Basal cells of taste

are stem cells that produce supporting cells which in turn become gustatory receptor cells.

20-20,000

audible range of hearing is _____-_______ hertz.

Otolithic membrane, hair bundle

because the _________ ________sits on top of the macula, tilting the head forward will cause the membrane and ototliths to slide forward (downhill) stimulating the hair bundle in that direction. If you accelerate, the head moves forward but the membrane/otoliths lag backwards and the hair bundle bends in the other direction. Movement of the _____ ______ (stereocilia and/or kinocilium) results in the release of neurotransmitter to the vestibular branches of the vestibulocochlear (VIII) nerve. You become aware! You are drooling!

500-5000

best hearing ranges between _____-_____ hertz.

cochlear branch

branch of the vestibulocochlear nerve that has spinal ganglion in the bony modiolus.

detached retina

can be caused by head trauma (a blow to the head such as from boxing) Fluid accumulates between layers of the retina Distorted vision or blindness

tastants

chemicals dissolved in saliva that stimulate gustatory receptor cells

odorants

chemicals that have an odor and can stimulate the olfactory apparatus.

vestibular apparatus

collective name given to the receptor organs for equilibrium. Structures of the inner ear include the saccule, utricle, and semicircular ducts.

supporting cells

columnar epithelial cells that provide physical support, nourishment, electrical insulation, and detox of chemicals that contact the olfactory epithelium or the olfactory receptors.

auditory tube or eustacian tube

connects middle ear with nasopharynx (top of throat). Allows pressure equalization of pressure on both sides of eardrum. Pain results without this equalization. Also, an opening for pathogens from nose/throat to middle ear and ear infection (otitis media) can result.

Visual Transduction

conversion of light to neural signals by visual receptors, occurs at the rods and cones

visual field

everything that can be seen by one eye is that eye's _______ ______.

Amacrine cells

excite bipolar cells if level of illumination of the retina changes.

gustatory hairs

extend outward from the receptor cell through the taste pore to contact food materials. One hair for each receptor cell.

hyperopia

farsightedness; eyeball is too short; convex glasses (coke bottle)

pigmented epithelium

first layer of the neural pathway of the retina, no vision; absorbs stray light to help keep image clear.

tarsal plate

gives form and support to the eyelids.

ceruminous glands

glands of the auditory canal, near exterior opening; secrete ear wax.

Olfactory (Bowman's ) glands

glands that occur throughout the olfactory epithelium and produce mucous. This mucous secretion dissolves the odorants so that transduction can occur and maintain moisture on the surface.

malleus

hammer, the handle of which attaches to the internal surface of the tympanic membrane and the head articulates with the incus.

loudness

increases as the same region of the membrane is stimulated continuously by sounds of the same pitch. A louder sound causes a greater vibration amplitude.

aqueous humor

it is a transparent watery fluid that nourishes the lens and cornea. It is produced by the ciliary body and drains continually to the scleral venous sinus and is replaced every 90 mins. it flows from the posterior chamber into anterior chamber through the pupil.

electromagnetic radiation

it is the energy in the form of waves that radiates from the sun, many types(x-rays, gamma-rays) but concerned with visible light portion.

vascular tunic

middle layer of the eyeball. It is composed of three parts: choroid, ciliary body, and iris.

tensor typani muscle

muscle attached to malleus and limits movement & stiffens eardrum to prevent damage from loud noises; supplied by trigeminal (V) nerve.

myopia

nearsightedness; eyeball is too long from front to back; concave glasses required.

semicircular ducts

o Within the semicircular canals lay the three _______ _______, each swollen at one end at the ampulla & all three connected at the utricle. Also called the membranous semicircular canals.

vestibule

oval-shaped central portion of the bony labyrinth.

Cochlear nuclei

part of the auditory pathway from the inner ear to the brain, receive auditory input from cochlea of the inner ear.

Choroid

posterior part of vascular tunic which is highly vascularized and lines the internal surface of sclera. Contains melanocytes which produce pigment melanin brown color.

olfactory hairs

project from dendrite into air path, cilia that bind to molecules called odorants.

eyelashes

project from the edge of each palpebra. Sebaceous glands at the base of these hair follicles release a lubricant into the follicles. If this becomes infected, a sty results.

ciliary processes

protrusions or folds on the internal surface of the ciliary body which secrete aqueous humor.

Posterior Semicircular Canal

semicircular duct that responds to the head tilting from side to side.

olfaction

sense of smell

basilar membrane

separates the cochlear duct from the scala tympani.

vestibular membrane

separates the cochlear duct from the scala vestibuli

bony labyrinth

series of cavities in the petrous portion of temporal bone. Lined with periostreum and filled with a cushioning fluid called perilymph, this labyrinth houses the semicircular canals and vestibule (with receptors for equilibrium) and cochlea (with receptors for hearing) in. Cavities are vesibule and semicircular canals.

stapedius muscle

smallest skeletal muscle of the body! Inserts onto the stapes. Protects oval window by dampening large vibrations; supplied by facial (VII) nerve

Basal cells

stem cells located between supporting cells which produce new olfactory receptors. Olfactory receptors are replaced monthly. Different than other mature neurons which you can have learned are not generally replaced.

Otorhinolaryngology

study of the science that deals with the ear, nose, and throat and their disorders. (ENT)

perforated eardrum

tearing or hole in the eardrum. (explosion, diving, ear infect.)

accommodation

the increase in curvature of the lens for near vision. The changing of shape of the lens so that light is focused is the function of the ciliary muscle pulling or relaxing the suspensory ligaments. This increase or decrease in the curvature of the lens is initiated by the ciliary muscle contraction or relaxation. Light rays inside 6 feet are more divergent and need more refraction and is accomplished by this.

lobule

the inferior portion (ear lobe)

Retina

the inner layer of the posterior 2/3 of eyeball. = Nervous Tunic, it is the starting point of the visual pathway-where pictures we see are focused.

Vitreous chamber

the large space between the lens and the retina, contains the vitreous body.

dynamic equilibrium

the maintenance of body position (mainly the head) relative to rotational acceleration or deceleration.

Nervous System

the network of billions of neurons and neuroglia, arranged in structures such as the brain, spinal cord, and sensory receptors, that produce and receive nerve impulses providing communication with and regulation of most body tissues.

Limbic System

the part of the brain, the forebrain, concerned with emotion and behavior.

intraocular pressure

the pressure in the eye produced by the aqueous humor. This pressure (16 mm Hg), along with the vitreous body, maintain the shape of the eyeball and keep the retina smoothly attached to the choroid so clear images are formed.

lens

the refractive media of the eye, transparent and avascular, functions to focus light rays on the retina for clear images. (ciliary body)

Chemical senses

the sense of smell and taste. the sensations that arise come from interaction of chemical molecules with smell or taste receptor cells.

gustation

the sense of taste and is a chemical sense.

fibrous tunic

the superficial (outer) layer of the eye consisting of anterior cornea and sclera.

Otolithic membrane

the thick gelatinous, glycoprotein layer that rests on the hair cells in the macula.

auditory ossicles

the three smallest bones of the body suspended by ligaments and connected to each other by synovial (fully movable) joints. They include:: malleus, incus, and stapes.

extrinsic eye muscles

these muscles are located outside of the eyeball and extend from the bony orbit of the eye and insert on the exterior surface of the eyeball at the sclera. 6 of these move each eye. 4 rectus muscles, and 2 oblique muscles, innervated by cranial nerves III, IV, or VI.

olfactory receptor

these receive chemical stimulation, lifespan about one month. Consist of a dendrite and axon. the chemical stimulation generates a potential which travels across the axon through the roof of the nasal cavity (cribiform plate) to the olfactory bulb neuron.

bipolar cell layer

this layer is excited by impulses from the photoreceptor layer , this layer contains horizontal & amacrine cells which modify nerve impulses, then it goes through the inner synaptic layer to the ganglion cell layer.

photoreceptor layer

this layer of the eye with rods and cones, transduces light into action potentials. these impulses travel through the outer synaptic layer to the bipolar cell layer.

low threshold

this means only a few molecules of an odor need to be present to be detected. We can detect odors down to the 1/25th millionth of a milligram per milliliter of air. e.g. methyl mercaptan and obnoxious sulfur molecule is added to ordorless natural gas so we can detect a leak.

vision, eye

this special sense is important to human survival when you consider that over 1/2 the sensory receptors in the body are located in the ______. (2 answers)

Occipital lobe

visual information in optic nerve travels to the ______ ____ in the brain for vision.

hypothalamus

visual information in optic nerve travels to the _________ to establish sleep patterns based upon circadian rhythms of light and darkness

Midbrain

visual information in optic nerve travels to the_________ for controlling pupil size & coordination of head and eye movements

sour, sweet, bitter, salty, and umami

what 5 primary taste can be distinguished?

10 days

what is the life of a gustatory receptor cell?

Cranial nerve (Facial nerve VII)

when this nerve is stimulated by certain chemicals you get a whiff and this sets the olfactory glands to going (runny nose) and the eyes to lacrimating (tears). This is an important protective feature built into these senses. examples: onions.