A&P1 CHAPTER 16 (plus lab 15)

medial and lateral canti

(commissures) or the far corners of the eye and secrete tears

hearing passageway

Audible sound range: 20-20,000 Hz. Sound waves→ auricle→ external auditory canal→ tympanic membrane→ malleus→ incus→ stapes→ oval window→ perilymph of the scala vestibuli→ vestibular membrane→ endolymph in the cochlear duct→ basilar membrane →hair cells bend → receptor potential→ nerve impulse →cochlear nerve. Sound wave → scala tympani→ round window →dissipates in middle ear.

taste and smell

Both similar receptor type Require the chemical to be dissolved in a solution in order to bind to the receptor Called chemoreceptors Chemical dissolves in solution & starts a cascade to open a ligand-gated channel

color and night blindness

Color blindness= inherited inability to distinguish between certain colors Result from the absence of one of the three types of cones Most common type: red-green color blindness Rare, but can also be injury related Night blindness or Nyctalopia= vitamin A deficiency

semicircular ducts (3)

Crista, a small elevation in the ampulla contain hair cells and supporting cells. Cupula, a mass of gelatinous material covering the crista. Head movement→ semicircular ducts and hair cells move with it→ hair bundles bend→ receptor potential→ nerve impulses→ vestibular branch of the vestibulocochlear nerve.

bleaching and regeneration of photopigment

Isomerization: In darkness, retinal has a bent shape called cis-retinal. Absorption of photon causes straightening of the retinal (trans-retinal). Bleaching: trans-retinal separates from opsin. Regeneration: trans-retinal→ cis-retinal.

inferior parts of the eyeball

Lens Lacks blood vessels, consists of a capsule with proteins (crystallins) in layers; transparent. Lens divides the eyeball into two cavities: anterior and posterior. Anterior cavity- further divided into anterior and posterior chambers. Both are filled with aqueous humor. Posterior cavity (vitreous chamber)-filled with vitreous humor

light and dark adaptation

Light adaptation: Dark → light. Faster. Dark adaptation: Light →dark. Slow. Cones regenerate rapidly whereas rhodopsin regenerates more slowly.

***processing visual input

Light hits the cornea→ Aqueous humor→ Pupil→ Lens→ Vitreous humor→ Retina From hitting the retina: Receptor potential in rods and cones of the retina→ signal carried to the optic disc→ optic nerve→ optic chiasm→ thalamus→ primary visual area of cerebral cortex in occipital lobe.

pupils dilating to light

Pupil is an opening in the center of the iris. Contraction of the circular muscles of the iris causes constriction of the pupil. Contraction of the radial muscles causes dilation of the pupil.

refraction of light rays

Refraction is the bending of light rays. The cornea and lens refract light rays.

cochlea

Snail-shaped Section through the cochlea shows three channels: cochlear duct, scala vestibuli and scala tympani Spiral organ or Organ of Corti hair cells

(T/F) sensorineural hearing loss results from damage to the inner ear or the vestibulocochlear nerve

T

(T/F) the auditory ossicles transmit vibrations through the round window

T

taste buds and papillae

Taste bud= made of three types of epithelial cells: supporting cells, gustatory receptor cells and basal cells About 50 gustatory cells per taste bud. Each one has a gustatory hair projecting through a taste pore Taste buds are found in the papillae Three types of papillae: vallate (circumvallate), fungiform and foliate

lacrimal apparatus passageway

Tears from the lacrimal apparatus- lacrimal glands→ excretory lacrimal ducts→ lacrimal puncta→ lacrimal canals→ nasolacrimal sac→ nasolacrimal duct

Equilibrium

Two types of equilibrium: Static= maintenance of the body position relative to the force of gravity Dynamic= maintenance of body position (mainly head) in response to rotational acceleration and deceleration Receptors for equilibrium are hair cells in the utricle, saccule and semicircular canals and are collectively called vestibular apparatus Tilting of the head forward→ sliding of the otolithic membrane bending the hair bundles→ receptor potential→ vestibular branch of the vestibulocochlear nerve.

tests for hearing loss

Weber and Rinne tests

what structure is the lens known as

a crystalline structure

what two cavities is the eyeball divided into

anterior and posterior cavities

anterior cavity

anterior to the lens and filled with aqueous humor produced constantly and drained by the scleral venous sinus and helps refract light

the fluid in the anterior cavity is known as __________, whereas the fluid in the posterior cavity is known as __________

aqueous humor and vitreous humor

suspensory ligaments

attaching the ciliary muscle to the lens

fibrous tunic of the eye

avascular with dense irregular collagenous CT sclera and cornea

vision light wavelengths determine what?

color (violet, indigo, blue, green, yellow, orange, and red)

outer ear

consists of the auricle (pinna) - a shell shaped structure composed of elastic cartilage that surrounds the opening to the external auditory canal tympanic membrane - a thin sheet of epithelium and CT separating the outer and middle ear

inner ear

contains the sense organs for hearing and equilibrium with cavities of bony labyrinth filled with a fluid of perilymph within that the membranous labyrinth containing a thicker liquid endolymph vestibule semicircular canals cochlea

what two components does the eye consist of?

eyelids and the eyeball

conductive hearing loss

from interference of sound conduction through the outer and middle ear

the structures of the cochlea are responsible for __________, the structures of the saccule and utricle are responsible for ___________ equilibrium, and semicircular ducts and ampulla are responsible for __________ equilibrium

hearing static rotational

what senses does the ear carry

hearing and equilibrium

choroid

highly vascular and makes up the posterior part of the vascular tunic brown to prevent light scattering in the eye

palpebral conjunctiva

internal structures of the palpebral that are lined with a thin mucus membrane

ciliary body

located at the anterior aspect of the vascular tunic produces aqueous humor

the pharyngotympanic tube connects the ________ to the ________

middle ear; pharynx

iris

most anterior portion of the vascular tunic consisting of muscles fibers arranged around the pupil fibers contract and the pupil constricts or dilates the iris is also divided into two smaller divisions: anterior segment and posterior segment

lateral rectus muscle

moves eye laterally

medial rectus muscle

moves eye medially

superior rectus muscle

moves eye superiorly

CN 1 olfactory nerve

penetrate holes in the cribriform plate to synapse on the olfactory build then sending impulses down to the olfactory tract to the olfactory cortex

the rods are responsible for ____________, whereas the cones are responsible for ___________

peripheral and dim light high acuity color vision

posterior cavity

posterior to the lens and contains a thicker vitreous humor which is present at birth and unchanged during life and helps refract light

what do external structures of the eyeball do?

protect the delicate eyeball and move the eyeball

middle ear

small air filled cavity within the temporal bone that houses auditory ossicles: malleus, incus, and stapes that transmit vibrations from the tympanic membrane to inner ear through the oval window (attached to the stapes) pharyngotympanic tube (auditory tube) - connects the middle ear to the pharynx (throat) and equalizes pressure

ciliary muscle

smooth muscle that controls the shape of the lens

perception

something the you are consciously aware of

error of localization (tactile localization) and two point discrimination

test sensory receptors of touch, pain, and temperature

sensation

the detection of changes in the internal and external environments conscious or subconscious

accommodation

the process by which the eye's lens changes shape to focus near or far objects on the retina (refection)

cochlea

the spiral cavity of the inner ear called the cochlear duct, containing the organ of Corti, which produces nerve impulses in response to sound vibrations hair cells depolarize in response to sound wave lengths and transmit sound impulses to the cochlear portion of the vestibulocochlear nerve round window allows the perilymph in the cochlea to vibrate

retina

thin and delicate structure that contains three layers of neurons: photoreceptors

semicircular canals

three canals within the inner ear that contain specialized receptor cells that generate nerve impulses with body movement housing semicuircular ducts and the ampullae that work with the organs of the vestibule to maintain equilibrium and allows for rotational equilibrium to maintain balance when moving

general senses

touch, pain, and temperature

ganglion cells

whose axons converge to form the optic nerves (CN2) that forms the optic chiasma

structures of the eye

Eyelids or palpebrae Protect the eye Eyelashes and eyebrows Protect the eye Extrinsic eye muscles Move the eye to allow peripheral vision

(T/F) astigmatism refers to irregularities in the surface of the retina

F retina -> cornea

gustation and how it works

Five types of taste: sour, sweet, bitter, salty and umami (meat taste) Tastant dissolves in saliva → plasma membrane of gustatory hair→ receptor potential→ nerve impulse via cranial nerves VII, IX and X→ medulla→ thalamus→ primary gustatory area of the cerebral cortex

equilibrium passageway

Hair cells of utricle, saccule and semicircular ducts→ Vestibular branch of the vestibulocochlear nerve →brain stem → cerebellum and thalamus→ cerebral cortex.

olfaction (smell)

Olfactory epithelium contains 10-100 million receptors Olfactory receptor= a bipolar neuron with cilia called olfactory hairs - Responds to chemical stimulation of an odorant molecule Supporting cells= provide support and nourishment Basal cells= replace olfactory receptors

wall of the eyeball

Three layers: Fibrous tunic- outer layer Sclera "white" of the eye Cornea-transparent coat in the front Vascular tunic or uvea- middle layer Choroid Ciliary body consists of ciliary processes and ciliary muscle Iris Retina- inner layer Optic disc Macula lutea- fovea centralis

anatomy of ear

Three main regions: External (outer) ear- auricle or pinna, external auditory canal, and tympanic membrane. Ceruminous glands- Middle ear- auditory ossicles: malleus, incus and stapes. Auditory (eustachian) tube. Internal (inner) ear- Labyrinth: bony and membranous. Bony labyrinth- perilymph and membranous labyrinth- endolymph. Oval window and round window- membranous regions.

photopigments

Two parts: opsin (four types, three in the cones and one in the rod) and retinal (light absorbing part). Rhodopsin= photopigment in rods. Cone photopigments= three types Determines which color it sees (specific) Absorption of light by a photopigment → structural changes

sensorineural hearing loss

damage to the inner ear and vestibulocochlear nerve

vestibule

egg shaped bony cavity that houses two structures responsible for equilibrium - saccule and utricle transmit impulses down the vestibular of the vestibulocochlear nerve and responsible for static equilibrium (maintaining balance when the body is not moving)

levator palpebrae superioris and the orbicularis oculi muscle

elevates upper eyelid and moves the eyeball

Romberg test tests for what?

functional vestibular apparatus for equilibrium

lacrimal apparatus

producing and draining tears consisting of the lacrimal gland (located in the superolateral orbit) and ducts that drain the tears it produces

olfactory receptor cells

receive chemicals interpreted as smells

bipolar neurons

receive input from the photoreceptors

taste buds

receptors located on projections from the tongue papillae (filiform, fungiform - scattered over the tongue, foliate - lateral tongue, and circumvallate - large; located at the posterior tongue)

lens

refracts light (bends) to allow light to come into the eye to focus it

sensory tunic

retina and optic nerve

photoreceptors

rods and cones

rods

scattered in the eye responsible for vision in dim light and peripheral vision can see black and white

Palpebrae

(eyelids) that cover and protect the eye

tarsal plate

(palpebra) composed of dense CT associated with a sebaceous gland (tarsal gland)

vascular tunic of the eye

(uvea) carries most of the blood supply to the tissues of the eye choroid, ciliary body, and iris

special senses

Include smell, taste, vision, hearing and equilibrium. Concentrated in specific locations in the head. Anatomically distinct structures. Complex neural pathway.

general senses

Include somatic sensations (tactile, thermal, pain, and proprioceptive) and visceral sensations. Scattered throughout the body. Simple structures.

near point and far point of vision

Increase in the curvature of the lens for near vision is called accommodation. Near point of vision is the minimum distance from the eye that an object can be clearly focused.

saccule and utricle

Macula= small thickened regions within the saccule and utricle Sensory structures for static equilibrium Also detect linear acceleration and deceleration Contain hair cells and supporting cells Stereocilia and kinocilium together called hair bundle Otolithic membrane rests on the hair cells and contain otolith ("big" salt crystals)

rods and cones

Named after the shapes of their outer segments. Rod= see better than cones at low light, don't see color (on/off - dim light) Cones= three types: red, green and blue. Outer segment- contains photopigments. Transduction of light energy into receptor potential occurs here. Inner segment- contains the nucleus, Golgi complex and mitochondria.

refraction abnormalities and correction

Nearsightedness (myopia)- close objects seen clearly. Image is focused in front of the retina. Correction- use of concave lens. Farsightedness (hyperopia)- distant objects seen clearly. Image is focused behind the retina. Correction- use of convex lens.

general senses including...

Nociceptors = detect pain Never become acclimated to a stimuli Osmoreceptors = detect water levels Internal only-used to determine hydration levels Thermoreceptors = detect heat gain or loss 2 sub types Krause's end-bulbs = detects heat loss (feel cold) Organs of Ruffini = detects heat gain (feel hot)

how olfaction works (10,000 different smells)

Odorant binds to the receptor of an olfactory hair→ G-protein activation→ activation of adenylate cyclase→ production of cAMP→ opening of Na+ channels→ inflow of Na+ →generator potential→ nerve impulse through olfactory nerves→ olfactory bulbs→ olfactory tract→ primary olfactory area of the cerebral cortex

the inner ear

Three parts: the semicircular canals, the vestibule (both contain receptors for equilibrium) and the cochlea (contains receptors for hearing) Semicircular canals: anterior, posterior and lateral Ampulla Vestibule consists of two sacs: utricle and saccule

extrinsic eye muscles

lateral rectus, medial rectus, superior rectus, inferior rectus, inferior oblique, superior oblique

lacrimal caruncle

located at the medial canthus contains sebaceous or mucus glands to lubricate the palpable and anterior surface of the eyeball

cones

located in the posterior portion of the eye (near the macula lutea with the fovea centralis) responsible for color and high acuity (sharp) vision in bright light

olfactory epithelium

located in the roof of the nasal cavity

cornea

makes up the anterior of the fibrous tunic the fourth refractory medium of the eye

inferior rectus muscle

moves the eye inferiorly

superior oblique muscle

moves the eyeball inferiorly and laterally

inferior oblique muscle

moves the eyeball superiorly and laterally

optic disc

no rods or cones and is known as a blind spot because of the lack of photoreceptors

special senses

vision, hearing, equilibrium, taste, and smell

lacrimal canals

where tears drain into which is near the medial commissure or canthus and then drain into the lacrimal sac (in the depression of the lacrimal bone)

nasolacrimal duct

where tears travel and empty into the nasal cavity inferior to the inferior nasal concha

bulbar conjunctiva

where the mucus membrane contracts the eyeball and it curls around that lines the eyeballs superficial surface

sclera

white part of the eyeball and makes up the posterior of the fibrous tunic white because of the collagen fibers making it thick and tough