E4 Ch. 16 Flashcards
what are the special senses
taste, smell, sight, hearing, and balance
define touch
a large group of general senses
describe special sensory receptors
localized (confined to head region), distinct receptor cells, special receptor cells
describe special receptor cells
neuron like epithelial cells or small peripheral neurons, transfer sensory info to other neurons in afferent pathways
another name for taste
gustation
another name for smell
olfaction
what are the receptors for taste and smell classified as
chemoreceptors
describe chemoreceptors
respond to chemicals; food dissolved in saliva, airborne chemicals that dissolve in fluids of the nasal mucosa
where do taste receptors occur
in taste buds; most found on surface of tongue, located w/in tongue papillae
name the 2 types of papillae (with taste buds)
fungiform and vallate papillae
what are the 2 major cell types found in taste buds
gustatory epithelial cells (supporting cells) and basal epithelial cells (gustatory cells)
how often are taste buds replaced
every 7-10 days
name the 5 basic qualities of taste
sweet, sour, salty, bitter, and umami
what chemical is “umami” elicited by
glutamate
what part of the brain does taste info. reach and though which nerves
the cerebral cortex; facial (VII) and glossopharyngeal (IX) nerves, some though vagus nerve (X)
describe the gustatory pathway
sensory neurons synapse in medulla located in solitary nucleus, impulses transmitted to thalamus to gustatory area of cerebral cortex in insula
olfactory epithelium is pseudostratified columnar and contains what 3 main cell types
olfactory sensory neurons, supporting epithelial cells, and olfactory stem cells
where are the cell bodies of olfactory sensory neurons located
in olfactory epithelium; have apical dendrite that projects to epithelial surface
what acts as a receptive structure for smell
olfactory cilia; mucus captures and dissolves oder molecules
describe filaments of the olfactory nerve
bundled axons of olfactory sensory neurons
what structures do the filaments of the olfactory nerve penetrate and where does it synapse with
penetrate cribriform plate of ethmoid bone to enter the olfactory bulbs and synapse w/ mitral cells
function of mitral cells
transmit impulses along olfactory tract to the limbic system and the piriform lobe of the cerebral cortex
anosmia
absence of the sense of smell, due to injury, colds, allergies, or zinc deficiency
uncinate fits
distortion of smells or olfactory hallucinations, often results from irritation of olfactory pathways after brain surgery or head trauma
olfactory epithelium is derived from what
olfactory placodes
how are taste buds developed
upon stimulation by gustatory nerves
list the accessory structures of the eye
eyebrows, eyelids, lacrimal caruncle, tarsal plates, tarsal glands, and conjunctiva
describe the conjunctiva and list its parts
transparent mucous membrane; palpebral conjunctiva, bulbar conjunctiva, and conjunctival sac
function of the lacrimal apparatus
keeps surface of eye moist
lacrimal gland
produces lacrimal fluid
lacrimal sac
fluid empties into nasal cavity
how many muscles control eye movement and where do they originate/insert
6; originate in walls of orbit, insert on outer surface of eyeball
what is the origin of the 4 rectus muscles of the eye
anular ring
list the 6 extrinsic eye muscles
lateral, medial, superior, inferior rectus, superior, inferior oblique
function of the sclera
provides shape and an anchor for eye muscles
function of limbus
junction b/t sclera and cornea
purpose of the scleral venous sinus
allows aqueous humor to drain
purpose of the choroid
vascular, darkly pigmented membrane that prevents scattering of light rays w/in the eye
what type of muscle is the iris composed of
smooth muscle
what is the pupillary light reflex
protective response of pupil constriction when a bright light is flashed in the eye
what two laters compose the retina
pigmented layer and neural layer
describe the pigmented layer of the retina
single layer of melanocytes
describe he neural layer of the retina and the 3 types of neurons found there
sheet of nervous tissue; photoreceptor, bipolar, and ganglion cells
describe the 2 main types of photoreceptors
rod cells- more sensitive to light; allows vision in dim light, black and white
cone cells- operate bes in bright light; enable high-acuity, color vision
ora serrata
neural layer ends at posterior margin of the ciliary body, pigmented layer covers ciliary body and posterior surface of the iris
what type of photoreceptors are found in the macula lutea
mostly cones
what type of photoreceptors are found in the fovea centralis
only cones; region of highest visual acuity
what two sources supply blood to the retina
outer third of retina receives from capillaries in the choroid
inner two-thirds of retina receives from the central artery and vein of the retina
function of the vitreous humor
transmits light, support posterior surface of lens, helps maintain intraocular pressure
function of aqueous humor
formed as a blood filtrate; supplies nutrients to lens and cornea
what structures make up the refractory media
lens, cornea, and humors
what is the refractory media
light bending structures
where does visual information travel to
mostly in cerebral cortex, other pathways include nuclei in the midbrain and diencephalon
describe the visual pathway to the cerebral cortex
light, beings at retina, activates photoreceptors which signal bipolar cells which signal ganglion cells then axons of ganglion cells exit eye as the optic nerve, axons to lateral geniculate nucleus of thalamus, synapse w/ thalamic neurons, fibers of optic radiation reach primary visual cortex
retinopathy of prematurity
blood vessels grow w/in eyes of premature infants, vessels have weak walls causing hemorrhaging and blindness
trachoma
contagious infection of the conjunctiva
what are the 3 main regions of the ear and what are their general functions
external- hearing
middle- hearing
internal- hearing and equilibrium
name the structures that make up the external ear
auricle, external acoustic meatus, and tympanic membrane
function of auricle
helps direct sounds
what components does the external acoustic meatus contain
hairs, sebaceous glands, and ceruminous glands
function of tympanic membrane
forms boundary b/t external and middle ear
what 3 parts comprise the bony labyrinth (internal ear)
semicircular canals, vestibule, and cochlea
what is the membranous labyrinth of the internal ear
series of membrane-walled sacs and ducts that fit w/in the bony labyrinth
what 3 parts comprise the membranous labyrinth of the internal ear
semicircular ducs, utricle and saccule, and cochlear duct
what type of fluid is found w/in the membranous labyrinth
endolymph
what type of fluid is found w/in the bony labyrinth
perilymph; continous w/ CSF
what area of the cochlea contains receptors for hearing
the cochlear duct (scala media)
spiral organ
receptor epithelium for hearing
function of inner hair cells
receptors that transmit vibrations of the basilar membrane
function of the outer hair cells
actively tune the cochlea and amplify the signal
function of the macula of the vestibule
monitor position of head when head is still
what planes do the 3 semicircular canals lie in
anterior and posterior semicircular canals= vertical plane @ right angles
lateral semicircular canal=horizontal plane
where is the crista ampullaris located and its function
housed in membranous ampulla; contains receptor cells of rotational acceleration, epithelium contains supporting cells and receptor hair cells
describe the steps of the auditory pathway
impulses from cochlear nerve to cochlear nuclei in medulla, neurons project to superior olivary nuclei, axons ascend in lateral lemniscus to inferior colliculus, projects to medial geniculate nucleus of thalamus to primary auditory cortex
describe the equilibrium pathway
transmits info on position and movement of head, most info goes to lower brain centers (reflex centers)
motion sickness
carsickness, seasickness, popular theory for a cause- mismatch of sensory inputs
Meniere’s syndrome
equilibrium is greatly disturbed, excessive amounts of endolymph in membranous labyrinth
conduction deafness
sound vibrations cannot be conducted to the inner ear, ruptured tympanic membrane, otitis media, otosclerosis
sensorineural deafness
results from damage to any part of the auditory pathway
presbycusis
gradual loss of hearing w/ age
