The SensesThe Senses

Chapter 8.2Chapter 8.2

How Does Vision Occur?How Does Vision Occur?

PathwayPathway

Light enters through pupilLight enters through pupil Lens focuses light on retinaLens focuses light on retina

PhotoreceptorsPhotoreceptors RodsRods

Night visionNight vision 75 – 150 million75 – 150 million Not color sensitiveNot color sensitive

ConesCones Require more lightRequire more light Best for daytimeBest for daytime 6/7 million6/7 million Sensitive to colorSensitive to color

Light energy changes into neuronal impulsesLight energy changes into neuronal impulses Optic nerve carries impulses from retina to the brainOptic nerve carries impulses from retina to the brain

Binocular FusionBinocular Fusion

Images received from two eyes into a Images received from two eyes into a single imagesingle image Retinal disparity is the difference between the Retinal disparity is the difference between the

images stimulating each eyeimages stimulating each eye

How Do We Hear?How Do We Hear?

Pathway of SoundPathway of Sound

Outer ear receives soundOuter ear receives sound Earflap directs sound down the auditory canalEarflap directs sound down the auditory canal Vibrations occur in the canal and vibrate the eardrumVibrations occur in the canal and vibrate the eardrum Middle ear is filled with 3 tiny bones (hammer, anvil, Middle ear is filled with 3 tiny bones (hammer, anvil,

stirrup)stirrup) Vibrates and pushes against the cochleaVibrates and pushes against the cochlea Inner ear= cochleaInner ear= cochlea

Contains fluids and neuronsContains fluids and neurons Pressure causes liquid to move hairs which are attached to Pressure causes liquid to move hairs which are attached to

sensory cells that pick up the motion and turn it into sensory cells that pick up the motion and turn it into neuronal impulsesneuronal impulses

Auditory nerve carries impulses to the brain (temporal lobe)Auditory nerve carries impulses to the brain (temporal lobe)

DeafnessDeafness

Conduction DeafnessConduction Deafness Hinders physical motion through rigidness Hinders physical motion through rigidness

of outer/middle ear bonesof outer/middle ear bones Hearing aids can helpHearing aids can help

Sensorineural DeafnessSensorineural Deafness Damaged cochlea, hair cells, or auditory Damaged cochlea, hair cells, or auditory

neuronsneurons Hearing aids don’t help, cochlear implant Hearing aids don’t help, cochlear implant

mightmight

Vestibular systemVestibular system

Regulates balanceRegulates balance PathwayPathway

3 semicircular canals provide the sense of 3 semicircular canals provide the sense of balance, located in the inner ear and balance, located in the inner ear and connected to the brain by a nerveconnected to the brain by a nerve

Hair cells project into the fluid in the canalHair cells project into the fluid in the canal When you move, canals move, and inertia When you move, canals move, and inertia

causes the fluid to move which bends the causes the fluid to move which bends the receptor cells that are in the fluidreceptor cells that are in the fluid

Over stimulated – causes dizzinessOver stimulated – causes dizziness

Chemical SensesChemical Senses

SmellSmell Vapors enter nose and come into contact with a Vapors enter nose and come into contact with a

special membrane w/ receptors in the upper nosespecial membrane w/ receptors in the upper nose Receptors send messages about smell through the Receptors send messages about smell through the

olfactory nerve olfactory nerve TasteTaste

Chemicals stimulate receptors on the taste budsChemicals stimulate receptors on the taste buds Taste, texture, and temperature info are relayed Taste, texture, and temperature info are relayed

to brainto brain

TouchTouch

Provides information on: Pressure, Provides information on: Pressure, warm, cold, and painwarm, cold, and pain

The more receptors the more sensitiveThe more receptors the more sensitive Skin is sensitive to temperature, but it Skin is sensitive to temperature, but it

has to be different than that of the skinhas to be different than that of the skin Pain is a warning sign to prevent Pain is a warning sign to prevent

damagedamage

Perceptions of PainPerceptions of Pain

Results fromResults from Intense pressureIntense pressure LightLight NoisesNoises HeatHeat

Two typesTwo types Sharp localized painSharp localized pain

What you feel immediatelyWhat you feel immediately Dull generalized painDull generalized pain

Pain you feel laterPain you feel later

Gate Control Theory of Pain Gate Control Theory of Pain

Lesson the pain by shifting our Lesson the pain by shifting our attention away from the pain attention away from the pain impulsesimpulses

Send other signals to compete with Send other signals to compete with the pain signalsthe pain signals

The gate limits the number of The gate limits the number of impulses that can be transmittedimpulses that can be transmitted Athletes can finish a game injuredAthletes can finish a game injured

KinesthesisKinesthesis

The sense of movement and body The sense of movement and body positionposition Works together with vestibular and Works together with vestibular and

visual senses for posture and balancevisual senses for posture and balance Comes from receptors of muscles and Comes from receptors of muscles and

tendons, and jointstendons, and joints No kinesthetic sensation, movements No kinesthetic sensation, movements

would be jerky and uncoordinatedwould be jerky and uncoordinated