Warm up 03/06/2012 The oily secretions that lubricate the eye are produced by the: A) ceruminous glands B) lacrimal glands C) meibomian glands D) apocrine glands E) ciliary glands The blind spot is located at the: A) fovea centralis B) ciliary body C) optic disk D) pupil E) choroid

Virtual Eye Dissection http://www.eschoolonline.com/company/examples/eye/eyedissect.html

Sensory System Ear: Sound & Balance

3 Parts: Outer – Middle - Inner

Outer Ear: Auricle Called the Pinna Fx: Collects sound waves

Outer Ear: External Auditory Canal Extends from Pinna to eardrum Fx: Transmits sound waves

Outer Ear: External Auditory Canal Produces Cerumen (wax) Fx: Traps foreign bodies

Middle Ear: Air-filled Converts sound waves to mechanical energy Amplifies it Conducts to next chamber

Components: Tympanic membrane – Eardrum Vibrates Sound to Mechanical Energy

Perforated Eardrum:

Inflammation of the middle ear Otitis Media Inflammation of the middle ear

Components: Ossicles – 3 bones Fx: Mechanical vibration Malleus (Hammer) Incus (Anvil) Stapes (Stirrup) Fx: Mechanical vibration

Middle Ear: Ossicles

Ear Ossicles

Middle Ear: Oval window - Tranfers mechanical vibration from middle ear to inner ear

View of OVAL WINDOW Oval Window

Middle Ear opens to Nasopharynx via Eustachian tube

Adjusts pressures between middle ear & outside Drains middle ear Eustachian Tube Fx: Adjusts pressures between middle ear & outside Drains middle ear Picture – as it opens to nasopharynx

Swallowing & yawning open it Eustachian Canal Normally closed Swallowing & yawning open it Tympanic membrane will not vibrate well if pressures not equal Fluid in canal behind ear drum

If fail to open, increased pressure (pain) and infections Eustachian Canal If fail to open, increased pressure (pain) and infections Fluid in canal behind ear drum

Requires Ear Tubes – drain the excess fluid & prevent infection

Labyrinth Inner Ear

Bony Chambers (fluid-filled) Inner Ear Bony Chambers (fluid-filled) Vestibule Semicircular Canals Cochlea

Inner Ear Bony Labyrinth

Inner Ear Bony Labyrinth Fluid-filled = Perilymph Membranous sac is suspended in the periliymph = Membranous labyrinth

Inner Ear Bony Labyrinth Sac contains thick fluid = Endolymph

Hearing and the Inner Ear - Cochlea Snail-like shape Membranous sac contains organ or Corti

Cochlear Ducts Membranous labyrinth Perilymph Endolymph Organ of Corti

Cochlear Ducts

Organ of Corti Contains specialized hearing receptors or hair cells Embedded in basilar membrane

Organ of Corti Hair cells covered by gel membrane (Tectorial membrane) Corti converts mechanical energy into electrochemical energy

Hearing Process Ossicles vibrate oval window Sets the fluids into motion (pressure waves)

Cochlear Ducts

Hearing Process Vibrate basilar membrane Hair cells rub tectorial membrane (bent)

Hearing Process Hair cells transmit impulse to cochlear nerve Interpretation of sound in temporal lobe

Hearing Process Hair cells transmit impulse to cochlear nerve Interpretation of sound in temporal lobe

Sound Energy to Hearing Interpretation Mechanical Energy Mechanical  Electrochemical

Ear Notes Part 1 Review

How old is your ear?

Balance: Static Equilibrium Position of head when not moving (which way is up) Membranous sacs in vestibule contain maculae

Maculae Physiology As head moves, otoliths roll in response to gravity Pulls on gel and bends hairs in receptors

Maculae Physiology Hair cells send impulse via vestibular nerve Signal to cerebellum for interpretation

Balance: Dynamic Equilibrium Rotation of head or movement is detected Membranous semicircular canals filled with endolymph

Crista Ampullaris Membranous semicircular canals contain crista ampullaris

Crista Ampullaris Contains receptor cells (w/ hairs) embedded in cupula (gel-like cap)

Ampullaris Physiology When head moves, endolymph lags behind Cupula drags against endolymph current and bends hairs

Ampullaris Physiology Stimulates hair cells to send impulse Vestibular nerve sends impulse to cerebellum

Bill Nye Sound