special senses

five special senses

• olfaction

• gustation

• vision

• equilibrium

• hearing

olfactory organs

provide sense of smell

• located in nasal cavity on either side of nasal septum

two layers of olfactory

olfactory epithelium and lamina propria

olfactory glands

secretions spot surfaces of olfactory organs

olfactory receptors

highly modified neurons

olfactory reception

• involves detecting dissolved chemicals as they interact with odorant-binding proteins

olfactory receptor population

-considerate turnover

• number of olfactory receptors decline with age

taste (gustation)

provides info about the foods and liquids consumed

taste receptors (gustatory receptors)

are distributed on tongue and portions of pharynx and larynx

• clustered into taste buds

taste buds

associated with epithelial projections (lingual papillae) on superior surface of tongue

taste buds contain

• Basal (stem) cells

• Gustatory cells

  • extend taste hairs

    • survive only 10 days before replacement

4 primary taste sensations

sweet, salty, sour, and bitter

umami

characteristic of beef/ chicken broths and parmesan cheese

• receptors sensitive to amino acids, small peptides and nucleotides

water

detected by water receptors in the pharynx

3 accessory structures of the eye

• palpebrae (eyelids)

• superficial epithelium of eye

  • lacrimal apparatus

eyelids (palpebrae)

• continuation of skin

  • blinking keeps surface of eye lubricated, free of dust and debris

palpebral fissure

gap that seperates free margins of upper and lower eyelids

medial canthus and lateral canthus

where to eyelids are connected

eye lashes

robust hairs that prevent foreing matter from reaching surface of eye

tarrsal glands

secrete lipid rich product that helps keep eyelids from sticking together

lacrima caruncle

• mass of soft tissue

• contains glands producing thick secretions

• contributes to gritty deposits that appear after good nights sleep

conjunctiva

epithelium covering inner surfaces of eyelids

lacrimal apparatus

• produces, distributes and removes tears

lacrimal gland (tear gland)

secretions contain lysozyme, an antibacterial enzyme

eyeball

• is hollow

• is divided into two cavities

  • large posterior cavity

  • smaller anterior cavity

sclera

outer white coating of the eye

cornea

transparent part of the eye that covers the iris and the pupil and allows light to enter the inside.

limbus

border between cornea and sclera

papillary constrictor muscles

changes diameter of pupil

neural tunic (retina)

a layer of photoreceptors cells and glial cells within the eye that captures incoming photons and transmits them along neuronal pathways as both electrical and chemical signals for the brain to perceive a visual picture.

inner neural part of retina

• contains visual receptors and associated neurons

• rods and cones are types of photoreceptors

rods

• do not discriminate light colors

• highly sensitive to light

cones

• provide color vision

  • densely clustered in fovea

aqueous humor

fluid circulates within the eye

• s a low-viscosity fluid continuously being secreted and reabsorbed

large posterior cavity (vitreous chamber)

vitreous body

• gelatinous mass

• helps stabilize eye shape and supports retina

lens fibers

filled with crystallins, which provide clarity and focusing power of lens

crystallins

a water-soluble structural protein found in the lens and the cornea of the eye accounting for the transparency of the structure.

cataract

condition in which lens has lost its transparency

light refraction

bending of light by cornea and lens

focal point

specific point of intersection on retina

focal distance

distance between center of lens and focal point

3 light refraction of lens

accomodation

astigmatism

visual acuit

accomodation

shape of lens changes to focus image on retina

astigmatism

condition where the light passing through cornea and lens is not refracted properly

• visual image is distorted

visual acuity

clarity of vision

• normal rating is 20/20

color vision

integration of info from red, green and blue cones

color blindness

inability to detect certain colors

visual data

from combined field of vision arrive at visual cortex of opposite occipital lobe

• left half arrive at right occipital lobe

  • right half arrive at left occipital lobe

auricle

• surrounds entrance to external acousting meatus

• protects opening of canal

• provides directional sensitivity

external acoustic meatus

ends at tympanic membrane (eardrum)

• detects sound waves and directs them towards the tympanic membrane

tympanic membrane

• is a thin, semitransparent sheet

  • seperates external ear from middle ear

ceruminousglands

integumentary glands along external acoustic meatus

• secrete waxy material (cerumen)

cerumen

keeps foreign objects out of tymphanic membrane

• slows growth of microorganisms in external acoustic meatus

middle ear aka tympanic cavity

communicates with nasoharynx via auditory tube

• permits equalization of pressures on either side of tympanic membrane

  • encloses and protects three auditory ossicles

    • malleus

    • incus

    • stapes

vibration of tympanic membrane

• converts arriving sound waves into mechanical movements

• auditory ossicles conducts vibrations to inner ear

innear ear

• contains fluid called endolymph

• bony labyrinth surrounds and protects membranous labyrinth

  • subdivided into 3 parts

    • vestibule

    • semicircular canals

    • cochlea

endolymph

s a physiological fluid that fills the inner ear's labyrinth and serves crucial sensory functions.

cochlear duct receptors

provide sense of hearing

as you get older

• tympanic membranes get less flexible

• articulations between ossicles stiffen