CHAPTER 6:SENSATION. SENSATION VS. PERCEPTION SENSATION = Activating one of our 5 senses PERCEPTION...

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CHAPTER 6:SENSATION

Transcript of CHAPTER 6:SENSATION. SENSATION VS. PERCEPTION SENSATION = Activating one of our 5 senses PERCEPTION...

CHAPTER 6:SENSATION

SENSATION VS. PERCEPTION

• SENSATION = Activating one of our 5 senses

• PERCEPTION = The process of understanding the sensations

SENSATION

• All senses work in a similar way, signals are sent to the brain and interpreted as language

• Sensory organs receive stimuli• Messages go through process of TRANSDUCTION= the signals are

transformed into neural impulses• Neural impulses travel to the THALAMUS, then to different cortices

of the brain• (WITH THE ONE EXCEPTION OF THE SENSE OF SMELL)

What we sense and perceive is influenced by many factorsExample: How long we are exposed to stimuli

Like today when you first put on your socks,

you felt it then but now you don’t

SENSORY ADAPTATION = Decrease in responsiveness to stimuli due to constant stimulation

SENSORY HABITUATION = Our perception of sensations is due to how focused we are on them

• We can voluntarily attend to a stimuli• Like now, as you listen to Mrs. Bird (or look at your phone)OR your attention can be involuntary, COCKTAIL-PARTY PHENOMENON =

For example: you’re talking to a friend when someone across the room yells your name, you will involuntarily switch to who is calling your name (new stimulus)

OUR SENSES: VISION•The dominant sense in human beings

•4 Step Process

STEP ONE: GATHER LIGHT• Color we perceive depends on

• Light intensity, how much energy the light contains• Light wavelength, determines the particular hue we see

• We see different wavelengths as different colors• Longest wavelength to shortest: Red, orange, yellow, green, blue, indigo,

violet

• ALL the color waves above mixed together = white or sunlight

• Objects appear black because they absorb all colors

• White objects reflect all wavelengths of light

STEP TWO: WITHIN THE EYE

A. Reflected light enters the eye through the CORNEA = protective covering that helps the eye focus the light

B. Light then travels through the PUPIL = like a shutter on a camera

IRIS = The muscle that controls the pupil,

can dilate to let more light in

http://www.youtube.com/watch?v=wkl9qAK7MsM

“The Human Eye in Extreme Detail”

STEP TWO CONTINUED…

C. ACCOMMODATION = the process of light entering the pupil being focused on the lens

LENS = curved and flexible structure in the eye that changes shape , focuses incoming rays onto the retina

*Test your Lens and feel the muscles adjusting the shape of your lens*

STEP TWO CONTINUED…

• D. As light passes through the lens it is flipped upside down and inverted. It is then projected onto the RETINA = the screen in the back of the eye• Specialized neurons on the retina are activated by different

wavelengths of light

STEP THREE: TRANSDUCTION

• Transduction = refers to the transition of the incoming stimuli into neural impulses

• There are several layers of neuron cells:

• CONES = 1st layer of cells directly activated by light. They detect color, fine detail in daylight and bright conditions

• FOVEA = indent at very center of the Retina, small area that contains high concentration of cones delivers high visual acuity

• RODS = receptor cells that detect black, white, gray and movements; used in peripheral and dim-lighting

• Rods outnumber cones ratio: 20 to 1

CONES & RODS

STEP THREE: TRANSDUCTION CONTINUED…• GANGLION CELLS = make up the optic nerve, if enough

rods & cones are fired these are triggered• The axons of these cells converge to make OPTIC NERVE =

carries neural impulses from the eye to the thalamus, specifically to the region called the LGN = Lateral Geniculate Nucleus• LGN = receives messages from the optic nerve then sends

the messages to the visual cortices in the occipital lobe

• BLIND SPOT = the spot where the optic nerve leaves the retina, it has no rods or cones, 176

TEST YOUR BLIND SPOT, GO TO PAGE 176 IN YOUR TEXTBOOK

LGN

STEP FOUR: VISION IN THE BRAIN

• This is the point where sensation ends and perception begins!• Visual Cortex in the occipital lobe receives impulses from the cells in

the retina• Impulses activate FEATURE DETECTORS = neurons in the visual cortex

that respond to different types of visual images • Examples: feature detectors for vertical lines, curves, motion…

• Discovered by David Hubel and Torsten Wiesel

LET’S REVIEW THE EYE

• http://www.youtube.com/watch?v=_5dEO-LRV-g

•“Physiology of the Eye”

THEORIES OF COLOR VISION• Competing theories exist explaining how and why we see color

• 1. TRICHROMATIC THEORY = the oldest and most simple theory

• We have 3 types of cones, they detect colors• BLUE

• RED

• GREEN

• Activated in different combinations these 3 produce different colors of spectrum

• Problem: can’t explain AFTERIMAGES = stare at green , look away see red• Stare at yellow, blue afterimage

LET’S TRY AN “AFTER IMAGE” PAGE 179

THEORIES OF COLOR VISION

• 2. OPPONENT-PROCESS THEORY = explains color blindness and afterimages

• Sensory receptors in the retina are arranged in pairs• Red & Green

• Yellow & Blue

• Black & White

• Color is processed in color pairs

• Lights that stimulates one half of the pair inhibits the other half

• Stare at Red, you fatigue your red sensors, when you look away you see the afterimage of the paired color, green

COLOR BLINDNESSGO TO PAGE 180-181

“THE ISHIHARA TEST”

THEORIES OF COLOR VISION• COLOR BLINDNESS =• Sex linked trait, more common in males, where individuals can’t see

colors, due to lacking a chemical usually produced by one or more types of cone• Two Types:

• DICHROMATIC = can’t see either red/green shades OR blue/yellow shades

• MONOCHROMATIC = causes people to see only shades of gray

• Most common type is red-green color blindness, resulting from a defective gene on the X-chromosome, for the green cone chemical.

SENSES AND ASSOCIATED RECEPTORS• Energy Senses: • Vision – Rods and Cones

• Hearing – hair cells in the cochlea

• Touch – temperature, pressure, pain nerve endings (in the skin)

SENSES AND ASSOCIATED RECEPTORS

• Chemical Senses:• Taste = Gustation

• sweet, sour, salty, bitter, umami taste buds (in papillae on the tongue)• Umami – (ooh-mommy) savory" or "meaty" taste

• Smell = olfaction • smell receptors connected to the olfactory bulb (in top of nose)

SENSES AND ASSOCIATED RECEPTORS

• Body Position Senses:• Vestibular sense – hair-like receptors in the three

semicircular canals (inner ear)• Causes dizziness and nausea

• Kinesthetic sense – receptors in the muscles and joints• Gives feedback about specific orientation of body parts

SENSE OF SMELL = OLFACTION

• http://www.youtube.com/watch?v=H_WFlTtPZmE

• The Sense of Smell, CNS

FIG. 6-23 RECEPTORS FOR THE SENSE OF SMELL (OLFACTION). OLFACTORY NERVE FIBERS RESPOND TO GASEOUS MOLECULES. RECEPTOR CELLS ARE SHOWN IN CROSS SECTION AT THE LEFT OF PART (A). (C) ON THE RIGHT, AN EXTREME CLOSE-UP OF AN OLFACTORY RECEPTOR CELL SHOWS THE FIBERS THAT PROJECT INTO THE AIRFLOW INSIDE THE NOSE. RECEPTOR PROTEINS ON THE SURFACE OF THE FIBERS ARE SENSITIVE TO DIFFERENT AIRBORNE MOLECULES.

© Richard Costano, Discover Magazine, 1993

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SENSE OF TASTE

• http://www.youtube.com/watch?v=KuP-Kj7MHes• The Taste Buds on the Tongue

FIG. 6-25 RECEPTORS FOR TASTE: (A) MOST TASTE BUDS ARE FOUND AROUND THE EDGES OF THE TONGUE. STIMULATION OF THE CENTRAL PART OF THE TONGUE CAUSES NO TASTE SENSATIONS. RECEPTORS FOR THE FOUR PRIMARY TASTE SENSATIONS CAN BE FOUND IN ALL OF THE SHADED AREAS, AS WELL AS UNDER THE TONGUE. THAT IS, ALL TASTE SENSATIONS OCCUR ANYWHERE THAT TASTE BUDS ARE FOUND. TEXTBOOKS THAT SHOW SPECIFIC “TASTE ZONES” FOR SWEET, SALT, SOUR, AND BITTER ARE IN ERROR. (B) DETAIL OF A TASTE BUD WITHIN THE TONGUE. THE BUDS ALSO OCCUR IN OTHER PARTS OF THE DIGESTIVE SYSTEM, SUCH AS THE LINING OF THE MOUTH.

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YOUR SENSE OF TASTE: DRAW ME IN YOUR NOTES

SENSE OF TOUCH

Skin Senses (Touch): Light touch, pressure, pain, cold, warmth

YOUR HOMEWORK:• Read over the rest of the senses on handout• Take notes • Must complete the labeling of all diagrams, use Chapter 6 = pg 174• Complete the crossword• Define the following terms• Skittle Research Study/ BONUS

• QUIZ next class over sensation

TERMS TO DEFINE, USE PAGES 183 TO 197

• Conduction deafness

• Nerve deafness• Stimulation

deafness• Tinnitus• Gustation• Anosmia• Somesthetic senses

• Kinesthetic sense• Vestibular senses• Skin receptors• Visceral pain• Referred pain• Somatic pain

• Acupuncture• Beta-endorphin• Gate-control

theory• Cochlea• Tympanic

membrane• Ossicles• Olfactory bulb