The Mechanism of Sense OrganMarcheli Alexandra T (3415126631)Leni Melisa (3415266

COORDINATION PROCESS*Stimuli receptors nervous system effectors -> response endocrine system

Coordination system

Sense, stimulus, receptor and sense organ

SenseStimulusEnergyReceptorSense organ1.sightLightElectromagneticPhotoreceptorEye2.HearingSoundMechanical deformationMechanoreceptorEar3.TasteChemical in foodChemicalChemoreceptorTaste bud4.TouchTouch,pain..Mechanical deformationMechanoreceptor, chemoreceptorSkin5.SmellChemical in airchemicalChemoreceptorNose

The Mechanism of SightMechanism of vison

Eye

Photoreceptor

The difference Between Rod and Cone

RodsConesPeriphery of retinaConcentrated at centreLarge number in yellow spotHigh visual sensitivityLowLow visual acuity High-detect dim light -night visioncannot detect colouronly detect strong lightday visiondetect colour

Peak Sensitivity of Rods and Cones

photochemical reactionUnder light, retinene undergoes isomeric change, rhodopsin breaks down to scotopsin and retinene (both colourless) Bleaching of visual pigments nerve impulse Light Rhodopsin Scotopsin + retinene (purple) Dark Nerve impulse *

Trichromatic theory of colour visionSensation of any given colour is determined by the relative frequency of impulses reaching the brain from each type of cone stimulate both green and red cones yellow-Colour blindness-Red-green colour blindness*

The mechanism of Hearing

Major Divisions of the EarPeripheral MechanismCentral Mechanism

Outer EarMiddle EarInner EarVIII Cranial NerveBrain

How Sound Travels Through The Ear...*

Outter Ear

Outter EarCerumen The purpose of wax:Repel waterTrap dust, sand particles, micro-organisms, and other debrisMoisturize epithelium in ear canalOdor discourages insectsAntibiotic, antiviral, antifungal propertiesCleanse ear canal

Middle EarTympanic Membrane

The Ossicular Chain

Eustachian Tube

Stapedius Muscle

Tympanic Membrane

Cone-shaped in appearanceabout 17.5 mm in diameter

The eardrum vibrates in response to sound pressure waves.

The membrane movement is incredibly smallas little as one-billionth of a centimeter

The Ossicular ChainA: MalleusB: IncusC: StapesOssicles are smallest bones in the bodyAct as a lever systemFootplate of stapes enters oval window of the cochlea

Eustachian Tube Lined with mucous membrane; connects middle ear to back of the throat (nasopharynx)Equalizes air pressureNormally closed except during yawning or swallowingNot a part of the hearing process

Stapedius MuscleConnects the stapes to the middle ear wallContracts in response to loud sounds; known as the Acoustic Reflex

Middle EarConductionConduct sound from the outer ear to the inner earProtectionCreates a barrier that protects the middle and inner areas from foreign objectsMiddle ear muscles may provide protection from loud soundsTransducerConverts acoustic energy to mechanical energyConverts mechanical energy to hydraulic energyAmplifierTransformer action of the middle earonly about 1/1000 of the acoustic energy in air would be transmitted to the inner-ear fluids (about 30 dB hearing loss)

Inner Ear

ChocleaSnail shaped. Have 3 canals they areScala Vestibuli Scala TympaniScala Media

*Acoustic energy, in the form of sound waves, is channeled into the ear canal by the pinna. Sound waves strike the tympanic membrane, causing it to vibrate like a drum, and changing it into mechanical energy. The malleus, which is attached to the tympanic membrane, starts the ossicles into motion. (The middle ear components mechanically amplify sound). The stapes moves in and out of the oval window of the cochlea creating a fluid motion. The fluid movement within the cochlea causes membranes in the Organ of Corti to shear against the hair cells. This creates an electrical signal which is sent via the Auditory Nerve to the brain, where sound is interpreted!

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