Anatomy: Midterm 2, Special Senses

Front 1

General senses

Back 1

large group of touch receptors

Front 2

Special senses

Back 2

taste, smell, sight, hearing, balance

Front 3

Special sensory receptors

Back 3

localized to head, not free endings of sensory neurons, special receptor cells = neuron-like epithelial cells or small peripheral neurons

Front 4

Taste

Back 4

gustation, chemoreceptors that respond to food dissolved in saliva fluids, tongue is stratified squamous epithelium

Front 5

Filiform papillae

Back 5

very numerous, small conical pointed in shape, line up in parallel rows which enables tongue to grasp food, NO taste buds

Front 6

Fungiform papillae

Back 6

mushroom shaped, spread over anterior 2/3rds of tongue, contain taste buds

Front 7

Vallate papillae

Back 7

V-shaped row bordering posterior third of tongue, anterior to terminal sulcus groove, contain taste buds

Front 8

Taste buds

Back 8

contain taste receptors, 50-100 epithelial cells, gustatory and basal cells, long microvilli (gustatory hairs) extend through taste pore to surface, cells replaced every 7-10 days

Front 9

Tastes

Back 9

sweet, sour, salty, bitter, umami (glutamate)

Front 10

Gustatory pathway

Back 10

through facial (7), glossopharyngeal (9), and vagus (10) nerves, bitter taste receptors found in stomach, neurons synapse in solitary nucleus of medulla, to thalamus and to gustatory area of cerebral cortex in insula

Front 11

Smell

Back 11

olfaction, chemoreceptors respond to airborne chemicals that dissolve in nasal mucosa, part of olfactory epithelium (pseudostratified simple columnar), 3 cell types: olfactory sensory neurons, supporting olfactory, basal epithelial cells

Front 12

Olfactory epithelium

Back 12

contain cell bodies of olfactory sensory neurons, have apical dendrite that projects to epithelial surface and ends in knob with olfactory cilia (receptive structures for smell), mucus captures/dissolves odor molecules

Front 13

Smell, body to brain

Back 13

gather into bundles of axon filaments of olfactory nerve, pass through cribiform plate of ethmoid bone, attach to olfactory bulbs and synapse with mitral cells, which transmit impulses along olfactory tract to limbic system or piriform lobe

Front 14

Anosmia

Back 14

absense of sense of smell due to injury, colds, allergies, etc

Front 15

Uncinate fits

Back 15

distortion of smells or olfactory hallucination, result from irritation of pathways, or after brain surgery or head trauma

Front 16

Eye and vision

Back 16

contain 70% of all sensory receptors in body, take up 40% cerebral cortex processing info, anterior 1/6th of eye is visible, lens anc iliary zonules divide eye into anterior/posterior segments

Front 17

Eyelids (palpebrae)

Back 17

separated by palpebral fissure, meet at medial/lateral angles, lacrimal caruncle = reddish elevation at medial canthus, tarsal plates = CT in eyelids, tarsal glands = modified sebaceous glands

Front 18

Conjunctiva

Back 18

transparent mucous membrane, palpebral conjunctiva, bulbar conjunctiva, conjunctival sac

Front 19

Lacrimal apparatus

Back 19

keeps surface of eye moist, lacrimal gland produces lacrimal fluid, lacrimal punctum, lacrimal canaliculus, lacrimal sac (fluid empties into nasal cavity), nasolacrimal duct, inferior meatus

Front 20

Extrinsic eye muscles

Back 20

control eye movement, originate in walls of orbit, insert on outer surface of eyeball, annular ring = origin of 4 rectus muscles (lateral/medial/superior/inferior rectus, superior/inferior oblique)

Front 21

Vitreous humor

Back 21

clear, jelly-like, transmits light, supports posterior surface of lens, helps maintain intraocular pressure

Front 22

Anterior eye chamber

Back 22

b/w cornea and iris

Front 23

Posterior eye chamber

Back 23

b/w iris and lens

Front 24

Aqueous humor

Back 24

formed from filtrate of capillaries in ciliary processes, flows from posterior chamber through pupil into anterior chamber, reabsorbed into venous blood by scleral venous sinus, renewed continuously, provides nutrients to lens and cornea

Front 25

Glaucoma

Back 25

intraocular pressure in anterior segment, occurs when aqueous humor drains more slowly than it forms, compression on retina and optic nerve, can lead to blindness

Front 26

Lens

Back 26

thick, transparent, biconvex disc, held in place by ciliary zonule, lens epithelium = covers anterior surface of lens, elongated lens fibers form bulk of lens, new lens fibers continuously added, lens enlarges throughout life

Front 27

Fibrous layer of eye

Back 27

external, dense CT in 2 different regions, sclera (white, provides shape and anchor for eye muscles) and cornea, limbus = junction b/w sclera and cornea, scleral venous sinus = allows aqueous humor to drain

Front 28

Cornea

Back 28

epithelium, thick layer of dense collagen-rich CT, avascular, gets oxygen from air and nutrients from aqueous humor, richly supplied with sensory nerve endings, mostly pain receptors

Front 29

Vascular layer of eye

Back 29

middle layer, composed of choroid, ciliary body, iris

Front 30

Choroid

Back 30

vascular, darkly pigmented membrane, under sclera, brown from melanocytes, prevents scattering of light rays in eye, corresponds to arachnoid and pia maters

Front 31

Ciliary body

Back 31

thickening ring of tissue that encircles lens, smooth muscle which focuses lens

Front 32

Ciliary process

Back 32

posterior surface of ciliary body

Front 33

Ciliary zonule

Back 33

suspensory ligament, halo of fine fibrils attached around entire circumference of lens

Front 34

Iris

Back 34

color of eye, attached to ciliary body and positioned anterior to ciliary body, smooth muscle, pupil = round opening, sphincter and dilatory pupillae muscles, vary size of pupil, papillary light reflex = protective response of pupil constriction when bright light is flashed

Front 35

Inner layer of eye

Back 35

retina = thin outer pigmented layer with melanocytes and thick inner neural layer with nervous tissue (ends at posterior margin of ciliary body, ora serrata retinae), optic nerve

Front 36

Macula lutea

Back 36

contains mostly cones

Front 37

Fovea centralis

Back 37

contains only cones and is region of highest visual acuity

Front 38

Optic disc

Back 38

blind spot

Front 39

Neural layer

Back 39

contains photoreceptor cells (rods and cones, signal bipolar cells), bipolar cells (signal ganglion cells to generate nerve impulse), ganglion cells (run along internal surface of retina), 4th type if interneurons (amacrine and horizontal cells) which process visual info, all converge to forms optic nerve

Front 40

Rod cells

Back 40

more sensitive to light, allow vision in dim light

Front 41

Cone cells

Back 41

operate best in bright light, enable high-acuity, color vision

Front 42

Photoreceptors

Back 42

rods/cones have inner and outer segment, outer segments are receptor regions that contain light absorbing pigments, light particles modify the visual pigment, generate nerve impulse

Front 43

Visual pathways to cerebral cortex

Back 43

begins at retina, light activates photoreceptors, signal bipolar cells, signal ganglion cells, axons exit eye as optic nerve, run through optic chiasm into optic tract, send axons to lateral geniculate nucleus of thalamus and synapse with thalamic neurons, fibers of optic radiation reach primary visual cortex

Front 44

Visual pathways to other parts of brain

Back 44

some axons from optic tracts brach to midbrain (superior colliculi controls extrinsic eye muscles, pretectal nuclei mediate papillary eye reflexes), others branch to suprachiasmatic nucleus to hypothalamus which processes visual input to help synchronize daily biorhythms with daylight-darkness cycle

Front 45

Blood supply to retina

Back 45

outer third gets it by capillaries in choroid, inner two-thirds serviced by central artery and vein of retina

Front 46

Cataracts

Back 46

lens becomes opaque, results in blindness

Front 47

Age-related macular degeneration

Back 47

involves buildup of deposits in retina, causes loss of vision in macula, which is center of visual field

Front 48

Trachoma

Back 48

contagious infection from Chlamydia of conjunctiva, causes eyelids to become distorted and inverted, results in eyelashes scraping against cornea which can lead to blindness from corneal scarring

Front 49

The ear

Back 49

receptor organ for hearing and equilibrium, outer/middle/internal ear

Front 50

Outer ear

Back 50

auricle (pinna) helps direct sounds, external acoustic meatus lined with skin/hair/sebaceous glands and ceruminous glands, tympanic membrane forms boundary b/w external and middle ears

Front 51

Otitis externa

Back 51

infection/inflammation of skin lining external acoustic meatus (external ear canal), swimmer’s ear can cause this

Front 52

Otitis media

Back 52

infection of tympanic membrane

Front 53

Middle ear

Back 53

tympanic cavity = air-filled space within petrous portion of temporal bone, medial wall penetrated by oval and round window, pharyngotympanic tube links middle ear and pharynx, tensor tympani and stapedius muscles = 2 tiny skeletal muscles in middle ear cavity

Front 54

Ear ossicles

Back 54

in middle ear: malleus (attached to eardrum), incus (b/w malleus and stapes), stapes (vibrates against oval window)

Front 55

Internal ear

Back 55

labyrinth, lies within petrous portion of temporal bone

Front 56

Bony labyrinth

Back 56

semicircular canals, vestibule, cochlea, filled with perilymph ( continuous with cerebrospinal fluid)

Front 57

Membranous layrinth

Back 57

series of membrane-walled sacs/ducts, fit within bony labyrinth, semicircular ducts, utricle and saccule, cochlear duct, filled with endolymph

Front 58

Semicircular canals/ducts

Back 58

facilitate equilibrium related to rotational acceleration of head

Front 59

Vestibule

Back 59

contains utricle (continuous with semicircular ducts) and saccule (continuous with cochlear duct), which contain macula (spot of sensory epithelium), facilitates equilibrium related to static equilibrium and linear acceleration of head

Front 60

Macula

Back 60

contains receptor cells (hair cells, base synapses with vestibular nerve), monitor position of head when head is still (static equilibrium) and when head is moving straight ahead (linear acceleration), contains columnar supporting cells, apex of stereocilia and one kinocilium, tips of hair cells embedded in otolithic membrane (jelly-like disc that contains crystal of calcium carbonate called otoliths)

Front 61

Cochlea

Back 61

contains cochlear duct, facilitates hearing, spiraling chamber, coils around a pillar of bone (modiolus), osseous spiral lamina = spiral of bone in modiolus, cochlear nerve runs through core of modiolus, vestibular membrane = roof of cochlear duct, basilar membrane = floor of cochlear duct (supports spiral organ of Corti)

Front 62

Cochlear duct

Back 62

lies between 2 chambers: scala vestibuli (connected to oval window) and helicotrema (region at apex of cochlea where scala vestibuli and scala tympani are continuous)

Front 63

Spiral organ of corti

Back 63

inside cochlear duct (scala media), receptor epithelium for hearing, consists of supporting cells are columnar epithelium, inner (transmit vibrations of basilar membrane) and outer (3 layers that actively tune cochlea and amplify signal) hair cells, stereocilia (tips of hairs) embedded in gel-like tectorial membrane, hair cells synapse with sensory fibers of cochlear nerve

Front 64

Auditory pathway from organ of corti in cochlea

Back 64

spiral organ of corti to spiral ganglion of cochlear nerve, cochlear nuclei (CN 8) of medulla, superior olivary nucleus of medulla-pons junction, inferior colliculus of midbrain, medial geniculate nucleus of thalamus, primary auditory cortex of temporal lobe

Front 65

Conduction deafness

Back 65

sound vibrations cannot be conducted to inner ear, ruptured tympanic membrane, otitis media, otosclerosis

Front 66

Sensorineural deafness

Back 66

results from damage to any part of auditory pathway

Front 67

Semicircular canals

Back 67

lie posterior and lateral to vestibule, anterior/posterior (in vertical plane) and lateral (horizontal plane) semicircular canals

Front 68

Semicircular duct

Back 68

snakes through each semicircular canal

Front 69

Membranous ampulla

Back 69

swelling in semicircular duct, located in bony ampulla, houses crista ampullaris (contains receptor cells of rotational acceleration and supporting cells and receptor hair cells [kinocilium and stereocilia], which project jelly-like cupula)

Front 70

Equilibrium pathway

Back 70

transmits info on position/movement of head, relayed from receptors in vestibule and semicircular canals of inner ear through vestibular nuclei in medulla to flocculonodular lobe in cerebellum

Front 71

Motion sickness

Back 71

mismatch of sensory inputs

Front 72

Meniere’s syndrome

Back 72

equilibrium is greatly disturbed, excessive amounts of endolymph in membranous labyrinth