Vestibular Sense Tells us where our body is

Vestibular Sense • Tells us where our body is oriented in space. • Our sense of balance. • Located in our semicircular canals in our ears.

Kinesthetic Sense • Tells us where our body parts are. • Receptors located in our muscles and joints. Without the kinesthetic sense you could touch the button to make copies of your buttocks.

Your Senses Vision, Hearing, Smell, Taste, Touch and Body Position

Touch

Touch (Somatosensation) • Touch receptors are on the skin • Four basic skin senses are – Pain, warmth, cold, and pressure • All skin sensations are a combination of these four basic senses • Burning = warmth + cold + pain

Pain • Why do we experience pain? ? – Your body’s way of telling you something has gone wrong • Biopsychosocial Perspective on Pain Biological Influence • Activity in spinal cord • Genetic differences in endorphin production • The brain’s interpretation of CNS activity Social-Cultural Influences • Presence of others • Empathy for others’ pain • Cultural expectations Psychological Influences • Attention to pain • Learning based on experience • Expectations Personal Experience Of Pain

Why do we feel Pain? Gate-control Theory of Pain • Pain messages travel on one set of nerve fibers containing pain gates. • The gates are open when pain is felt. • Other sensory messages go through another set of fibers. • The nonpain fibers can close the pain gates to stop the sense of pain.

Body Senses

Kinesthetic Sense • The system for sensing the position and movement of individual body parts • Relies on receptor cells from the muscles and joints • One’s leg “falling asleep” is a disruption of the kinesthetic sense

Vestibular Sense • The system for sensing body orientation and balance • Relies on fluid in the semicircular canals of the inner ear • Spinning in circles disrupts the fluid.

Vision

http: //webvision. med. utah. edu/imageswv/pupil. jpeg http: //www. fofweb. com/Electronic_Images/onfiles/Sci. Hum. Phys 11 -22 c. gif http: //www. cs. umsl. edu/~sanjiv/cs 440/mike_project/retina. gif www. photo. net

The Visual System • Far more of the brain is devoted to vision than to any other sense modality. Why? – Enormous importance to our lives – more than any other sense – Human visual system is engaged in complex processing activities

Vision • Photoreceptors in our eyes gather light • Convert its physical energy into neural messages • And send it to the occipital lobe in the brain for decoding and analyzing That’s basically it….

Why Two Eyes? • Produces binocular disparity – Constructing three dimensional world out of two dimensional retinal images http: //cgw-shader-pack-1. customgraphicwork. com/Pack 1/CGWEye-show 1. jpg http: //www. calc 101. com/animations/3 DKaleidoscope. gif

Vision • How does our material body construct our conscious visual experience? • How do we transform particles of light energy into colorful sights?

Transduction Conversion of one form of energy to another. Stimulus energies changed to neural impulses. Light Eyes Transduction How is this important when studying sensation? For example: Light energy to vision. Chemical energy to smell and taste. Sound waves to sound. Neural messages What you consciously see

We only use light energy to see.

What makes up a light wave?

Wavelength • The distance from the peak of one light wave to the peak of the next. • The distance determines the hue (color) of the light we perceive.

Intensity The amount of energy in a light wave. Determined by the height of the wave. The higher the wave the more intense the light is. (brightness)

How do we see in color? What color is this dragon?

Color • The dragon is anything but red. • The dragon rejects the long wavelengths of light that to us are red - so red is reflected of and we see it. • Also, light has no real color. • It is just energy turned into color by our eyes • It is our mind that perceives the color.

What enables you to perceive color? ? Two major color theories

Young-Helmholtz Trichromatic (three color) Theory • Guessed that we have 3 different types of photoreceptor cells in our eyes. • Each with differing sensitivities to different light wavelengths • Realized that any color can be created by combining the light waves of three primary colors • Most colorblind people simply lack cone receptor cells for one or more of these primary colors. – Not really blind – just limited in what colors they can see Click here to simulate color blindness

Opponent-Process Theory • The visual system has receptors that react in opposite ways to three pairs of colors (red-green, blue-yellow, and white-black). – These are antagonist/ opponent colors. – Light that stimulates one half of the pair inhibits the other half – Produces afterimages Afterimages – colors perceived after other, complementary colors are removed

Afterimage Effect

Parallel Processing • The processing of several aspects of a problem simultaneously. Color Motion Form Depth

Feature Detection The concept that specific nerve cells in the brain respond to specific features of the stimulus, such as shape angle or movement.

Other Vision Concepts

Hue • The color of light as determined by the wavelength of the light energy • Includes: red, orange, yellow, green, blue, indigo and violet (ROY G BIV) • The eye can detect 7 million separate hues

Amplitude • The brightness of light as determined by height of the wave • The taller the wave, the brighter the color

THE EYE

THE EYE- inside

Cornea • The clear bulge on the front of the eyeball • Begins to focus the light by bending it toward a central focal point • Protects the eye

Parts of the Eye – Cornea

Iris • A ring of muscle tissue that forms the colored portion of the eye; creates a hole in the center of the iris (pupil) • Regulates the size of the pupil by changing its size--allowing more or less light to enter the eye

Parts of the Eye - Iris

Pupil • The adjustable opening in the center of the eye that controls the amount of light entering the eye (surrounded by the iris) • In bright conditions the iris expands, making the pupil smaller. • In dark conditions the iris contracts, making the pupil larger.

Parts of the Eye - Pupil

Lens • A transparent structure behind the pupil; focuses the image on the back of the eye (retina) • Muscles that change thickness of the lens change how the light is bent thereby focusing the image • Glasses or contacts correct problems in the lens’ ability to focus.

Parts of the Eye - Lens

Retina • Light-sensitive surface with cells that convert light energy to nerve impulses • At the back of the eyeball • Made up of three layers of cells – Receptor cells – Bipolar cells – Ganglion cells

Parts of the Eye - Retina

Receptor Cells • These cells are present in every sensory system to change (transduce) some other form of energy into neural impulses. • In sight they change light into neural impulses the brain can understand. • Visual system has two types of receptor cells – rods and cones

Rods • Visual receptor cells located in the retina • Can only detect black and white • Respond to less light than do cones

Cones • Visual receptor cells located in the retina • Can detect sharp images and color • Need more light than the rods • Many cones are clustered in the fovea.

Rods and Cones

Fovea • The central focal point of the retina • The spot where vision is best (most detailed)

Types of Vision

Processing Bipolar Cells • Gather information from the rods and cones and pass it on to the ganglion cells • Cells that form the middle layer in the retina Ganglion Cells • Pass the information from the bipolar cells through their axons • Together these cells form the optic nerve. • The top layer of the cells in the retina

Visual Processing in the Retina

Optic Nerve • The nerve that carries visual information from the eye to the occipital lobes of the brain

Parts of the Eye – Optic Nerve

Blind Spot • The point at which the optic nerve travels through the retina to exit the eye • There are no rods and cones at this point, so there is a small blind spot in vision.

Parts of the Eye – Blind Spot

Hearing Aka: Audition

Why do we have two ears?

Sound • Sound, like light, comes in waves • Sound is vibration • Features of sound include: – Pitch – Hertz – Decibels

Pitch • A sound’s highness or lowness • Dependent on the frequency of the sound wave • Is measured as hertz (Hz)

Hertz (Hz) • A measure of the number of sound wave peaks per second; measures “frequency” • Determines the pitch of the sound • Human hearing goes from 20 Hz to 20, 000 Hz

Decibel (d. B) • A measure of the height of the sound wave • Determines the loudness of the sound • Sometimes called amplitude

Amplitude is how loud the sound is. The higher the crest of the wave is the louder the sound is. It is measured in decibels.

Hearing: The Structure of the Auditory System

Parts of the Ear – Sound Waves

Auditory Canal • The opening through which sound waves travel as they move into the ear for processing • Ends at the tympanic membrane (eardrum)

Parts of the Ear – Auditory Canal

Tympanic Membrane (eardrum) • The tissue barrier that transfers sound vibration from the air to the tiny bones of the middle ear • Can be damaged by objects in the ear or exceptionally loud noises

Parts of the Ear – Tympanic Membrane

Ossicles • Three tiny bones that transfer sound waves from the eardrum to the cochlea • Hammer, anvil and stirrup

Parts of the Ear - Occicles

Cochlea • A hearing organ where sound waves are changed into neural impulses • The major organ of hearing • Filled with fluid; a snail shaped body tube Cochlear Implant

Parts of the Ear - Cochlea

Hair Cells • The receptor cells for hearing in the cochlea that change sound vibrations into neural impulses • Similar to the rods and cones within the eye

Parts of the Ear - Hair Cells

Auditory Nerve • The nerve that carries sound information from the ears to the temporal lobes of the brain

Parts of the Ear – Auditory Nerve

Semicircular Canals • Organs in the inner ear used in sensing body orientation and balance (vestibular sense) • Relies on fluid in the canals • Spinning in circles disrupts the fluid.

Parts of the Ear – Semicircular Canals

Divisions of the Ear • Ear’s structure can be divided into: – The outer ear – The middle ear – The inner ear

Divisions of the Ear

How do we perceive differences in pitch? There are two theories……. .

Place Theory • We hear different pitches because different sound waves trigger activity at different places along the cochlea’s basilar membrane.

Frequency Theory • We sense pitch by the basilar membrane vibrating at the same rate as the sound. • But this theory has trouble explaining high pitch sounds because our hairs cannot vibrate at certain speeds. What about above our absolute threshold? ? Fact or Fiction? ?

Hearing loss • Conduction Hearing Loss: caused by damage to mechanical system of ear. • Sensorinueral hearing loss: caused by damage to cochlea’s receptor cells or to auditory nerves. Cochlea Implant

Smell and Taste

Why do we study smell and taste together? • SENSORY INTERACTION: the principle that one sense may influence another.

Taste • Taste is a chemical sense. • Receptor cells are located primarily on the tongue and in the mouth. • Four different tastes: – Salty, sweet, sour and bitter • Damaged taste receptor cells are replaced within a few days.

How do we taste? • Taste (and smell) are chemical senses. What is the central muscle involved in taste?

Taste Buds Map out the tongue

Papillae • Those bumps on our tongue are called Papillae. • Papillae help grip food while your teeth are chewing. • They also have another special job they contain your taste buds

TASTE http: //bookworm. com. sg/e-book-preview/e-science-10 -senses-pg 05 -pic 04 b. gif

PTC Strips

Supertasters • People with an abundance of taste receptors • Approximately 25% of the population

Nontasters • People with a minimum of taste receptors • Taste with less intensity than the rest of the population • Approximately 25% of the population

But what about smell? Can our sense of smell be biologically based?

Smell • Smell is a chemical sense. • Olfactory cells in the upper nasal passages detect molecules in the air. • Taste and smell interact to produce flavor.

Olfactory Cells • The chemical receptor cells for smell • Located in the nasal passages

Gender related odors • Can you smell the difference between?

So can we smell the difference? • Well…. yes and no. Pheromones • Chemical messengers that are picked up through our sense of smell. • Founded in the early 1930’s by studying silkworms. • Jury is still out on whether they exist in humans.

The End