HUMAN ANATOMY: Special Senses

chemoreceptors, mechanoreceptors, and photoreceptors

smell, taste, hearing & equilibrium (balance), and sight

smell & taste

hearing & equilibrium

sight

smell

pseudostratified ciliated columnar epithelium

location where chemoreceptors synapse with interneurons; part of the CNS

mucus traps molecules from inhaled air => olfactory receptors are activated => like molecules synapse in a glomerulus => activated interneurons send signal through the olfactory tract to the olfactory cortex

vallate (circumvallate) papilla and fungiform papilla

create the rough texture of the tongue as they allow it to grip food; no tastebuds

composed of: 50-100 cells, a taste pore, gustatory receptor cells with hair, supporting cells, and basal cell

respond to chemicals in food and drink

insulatory and make up half of all cells

immature cells that replace old/ damaged cells every 7-10 days

taste fibers of cranial nerve; transport signal from gustatory receptor cells to CNS

place when dissolved molecules/chemicals and saliva are presented

these cells are activated once the microvillus (hair) comes in contact with the molecules from the taste pore

combination of taste, smell, and texture

our most dominant sense; where 70% of all sensory receptors are located

colored portion of the eye made up of smooth muscle; contracts/enlarges the pupil to let in light entering the eye and contains melanocytes

hole within the iris that can change the diameter

white of eye that wraps around the entire eye and gives the eye its shape, extension of dura mater; dense irregular CT

palpebra

opening created when eyelid is up

one per eye; serous cell that produces tears, fluid washes away irritants from surface of eye

lacrimal canaliculi => lacrimal sac => nasolacrimal duct => nasal cavity

six per eye that coordinate eye movement; attach to sclera

misaligned eyes “cross eyed”; when extrinsic muscles don’t function the way they should which can result in double vision, lack of stereoscopic vision, and amblyopia

the ability for the brain to register three dimensional objects

reduced vision in the waker or “lazy” eye

the avascular outer layer of the eye (extension of dura mater) that provides protection and mechanical support; consists of the sclera and cornea

transparent part of the eye that covers the iris and the pupil and allows light to enter the inside; parallel collagen fibers/ dense regular CT

covers the sclera and is where the blood vessels sit

pink eye

lines the inner surface of the sclera and made up of three major parts: choroid, iris, and ciliary body

vascular, dark surface that absorbs excess light

brown pigment that determines eye color

smooth muscle that controls the shape of the lens, which focuses light on the back surface of the eye; capillaries within produce the aqueous humor

produced by the ciliary body and circulates through the anterior segment of the eye; behaves as the CSF in the eye

condition where aqueous humor is drained slower than its produced increasing pressure within the eye and damaging the retina

innermost layer of the eye composed of the retina

structure in the eye composed of the pigmented and neural layers; nerve tissue at the back of the eye that receive images and sends them as electric signals through the optic nerve to the brain

single epithelial layer within the retina that contains melanin granules that lies against the choroid; absorbs light and nourishes the neural layer

layer within the retina that is in contact with the lumen of the eye and contains three type of neural cells; photoreceptor cells, bipolar cells, and ganglion cells

type of photoreceptor in the retina; most numerous and most sensitive to light (good for low light) side of eye

type of photoreceptor in the retina; works best in bright light and has three subtypes (blue, red, green) back of eye

cells in the retina that are activated by cones and rods

cells in the retina that are activated by bipolar cells and transmit impulse to the brain through the optic nerve

cones and rods

location at the back of the eye where axons of the ganglion cells are leaving the eye; lack of cones and rods

region at the posterior pole of the eye where light comes in directly giving you the best possible visual of an object whilst looking directly at it in good light conditions; fovea centralis and mostly cones

the very center of the macula lutea composed of cones completely and gives maximum visual acuity

concentric layers of fibers suspended in the ciliary body that separates the anterior and posterior segments of the eye; changes shape to focus light

normal eye; light focuses on retina

nearsighted eye as the light focuses on the front of the retina; concave lens

farsighted eye as light focuses behind the retina; convex lens

lens becomes less elastic as we age

surface of the cornea is reshaped using a laser in order to properly redirect light onto the retina

abnormal shape of cornea surface causes light rate to scatter differently resulting in two or more focal points

segment that exists between the cornea and lens containing aqueous humor; supplies nutrients/oxygen to the lens and cornea, blood filtrate from ciliary body, and removed at scleral venous sinus

segment that exists behind the lens containing the vitreous humorl holds everything into place

thick fluid of the posterior segment that supports the lens and retina and is composed of 98% water as well as collagen

a hole or small tear in the retina that peels retina from choroid later and leaks vitreous humor in the retina causing photoreceptors to die

hearing and equilibrium

region of the ear that collects and directs sound waves

region of the ear that amplifies and transmits sound waves; air filled cavity

sensory organs for hearing and equilibrium; fluid filled cavity

structure of the external ear; outer fleshy portion of the ear that provides protection and funnels sound

structure of the the external ear; air filled canal lined with stratified squamous epithelium

glands within the external acoustic meatus that secrete cerumen (wax) which inhibits microorganism growth

structure that separates the external (skin lining) and middle ear (mucous membrane lining); vibrates when hit by sound waves

membrane will heal but scar tissue can affect hearing

structure of the middle ear; small bones that transmit vibration from tympanic membrane towards inner ear (malleus, incus, stapes)

equalizes pressure with outside air; connects middle ear to nasopharynx

tympanic membrane => malleus => incus => stapes => oval window

small muscle that attaches to malleus that tenses up to control strong vibrations that could damage receptors in inner ear

small muscle that attaches to stapes that tenses up to control strong vibrations that could damage receptors in inner ear

structure of the middle ear; “entrance” for sound vibrations to the inner ear

structure of the middle ear; “exit” for sound vibrations from the inner ear

cavity where all inner ear structures are located containing the perilymph (like CSF) and the regions of the: cochlea, vestibule, and semicircular canals

water balloon like structure that contains endolymph with these regions floating within: cochlear duct (sound) and utricle, saccule, and semicircular ducts (equilibrium)

bony labyrinth

membranous labyrinth

oval window => scala vestibule (perilymph) => scala media (endolymph) => crosses basilar membrane (sound receptors) into scala tympani (perilymph) => round window

perilymph

endolymph

sound receptors

perilymph

region of cochlear duct with simple columnar epithelium that contains receptor cells; sits on basilar membrane

mechanoreceptor cells that are suspended between the tectorial and basilar membrane

organelles of hair cells that initiate an electrical impulse when bent

rigid sheet of collagen fibers that stereocilia are embedded within

sensory neuros

protection and support

the basilar membrane vibrates when sound passes from the scala media to scala tympania; hairs between the basilar and tectorial membrane bend generating an impulse

oval window

cochlear duct

made up of the membranous structures of the utricle and saccule; equilibrium

responds to acceleration in horizontal direction