CHAPTER 13 THE SENSES RECEPTORS RECEIVE INFORMATION AND SEND IT TO THE BRAIN FOR PROCESSING.
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Transcript of CHAPTER 13 THE SENSES RECEPTORS RECEIVE INFORMATION AND SEND IT TO THE BRAIN FOR PROCESSING.
CHAPTER 13
THE SENSES
RECEPTORS
• RECEIVE INFORMATION AND SEND IT TO THE BRAIN FOR PROCESSING
4 RECEPTOR TYPES
1. CHEMORECEPTORS- RESPOND TO CHEMICALS- SMELL, TASTE, BLOOD pH,
• PAIN RECEPTORS- SENSE CHEMICALS PRODUCED BY DAMAGED CELLS
2. MECHANORECEPTORS
• STIMULATED BY CHANGES IN PRESSURE OR MOVEMENT
• TOUCH, HEARING, POSITION OF BODY PARTS, BALANCE
3. THERMORECEPTORS
• COLD, WARMTH
• IN SKIN AND HYPOTHALAMUS (to regulate body temp.)
4. PHOTORECEPTORS
• RESPOND TO LIGHT
• CONES- Sense COLOR
• RODS- Sense only BLACK AND WHITE
• Rods work better than cones when it is fairly dark
SENSATION
• THE ARRIVAL OF ELECTRICAL IMPULSES AT THE BRAIN (CEREBRUM- the front part of brain)
• PERCEPTION- INTERPRETING THE MEANING OF THE SENSATION
ADAPTATION
• RESPONSE TO A REPEATED STIMULUS
• RECEPTORS STOP SENDING IMPULSES OR THE BRAIN FILTERS THEM OUT
• Farmers don’t notice manure smell anymore• People living beside railroads no longer get
awakened by trains at night
PROPRIOCEPTION
• SENSING THE POSITION OF BODY PARTS
• DEPENDS ON MUSCLE, TENDON AND LIGAMENT TENSION
RECEPTORS IN THE SKIN
2 LAYERS
• EPIDERMIS- PAIN
• DERMIS- TOUCH, COLD, HEAT, PAIN
REFERRED PAIN
• INTERNAL PAIN IS “FELT” SOMEWHERE ELSE ON THE BODY
• EX. HEART ATTACK “FELT” IN LEFT ARM
TASTE
• RECEPTORS ARE LOCATED IN PAPILLAE (BUMPS ON TONGUE)
• BITTER, SWEET, SALTY, SOUR
• TASTE = A COMBINATION OF THESE 4 SENSATIONS
SMELL
• OLFACTORY CELLS IN THE ROOF OF THE NASAL CAVITY
• 1,000 DIFFERENT RECEPTORS• ODORS STIMULATE DIFFERENT
COMBINATIONS OF RECEPTORS• NERVES CONNECT TO EMOTIONAL
CENTER OF THE BRAIN• TASTE BUDS ALSO STIMULATED
VISION
• SCLERA- TOUGH WHITE OUTER COVERING
• CORNEA- PUPIL COVER
• LENS- FOCUS LIGHT RAYS
• RETINA- BACK OF EYE WHERE IMAGE IS FOCUSED
• IRIS- REGULATES LIGHT
EYE
• FILLED WITH FLUID
• GIVES IT SHAPE
• FRONT SECTION- WATERY FLUID
GLAUCOMA- CAUSED WHEN DRAINS CLOG AND PRESSURE BUILDS
• REAR SECTION- JELLO LIKE FLUID
FOCUSING
• TINY MUSCLES CONTROL THE SHAPE OF THE LENS SO THAT LIGHT IS FOCUSED PROPERLY WHEN IT HITS THE RETINA
• CLOSE OBJECTS- MUSCLES CONTRACT, EYE STRAIN
• OLD AGE- BIFOCALS, CATARACTS
RETINA
• RODS, SENSE Black and White IN LOW LIGHT
• CONES SENSE Red,Green,Blue IN BRIGHT LIGHT
FOVEA- SMALL CENTRAL REGION OF RETINA FILLED WITH LOTS OF CONES
ABNORMALITIES
COLORBLINDNESS- LACK OF CONES
• CORRECTIVE LENSES- NEEDED FO MISSHAPEN EYEBALL OR LENS
NEARSIGHTED- EXTRA LONG EYEBALL
FARSIGHTED- EXTRA SHORT EYEBALL
ASTIGMATISM- UNEVEN LENS
HEARING
• OUTER EAR= PINNA AND AUDITORY CANAL
• MIDDLE EAR= TYMPANIC MEMBRANE + OSSICLES (bones)
Ossicles= MALLEUS (hammer), INCUS (anvil) AND STAPES (stirrup) HIT OVAL WINDOW of cochlea
EUSTACHIAN TUBE- EQUALIZES PRESSURE IN MIDDLE EAR- also called auditory tube
INNER EAR
• COCHLEA (HEARING) + VESTIBULE AND SEMICIRCULAR CANALS (BALANCE)
SENSING SOUND
• SOUND= AIR PRESSURE WAVES• EARDRUM VIBRATES• STAPES HITS OVAL WINDOW• PRESSURE WAVES OF FLUID IN
COCHLEA BENDS STEREOCILIA (HAIR CELLS) ALONG THE MEMBRANE
• Creates impulses which go to brain
BALANCE
• INNER EAR
• ACCELERATION- SEMICIRCULAR CANALS
• POSITION- VESTIBULE
ACCELERATION
• SEMICIRCULAR CANALS- ONE FOR EACH DIMENSION OF MOVEMENT
• MOVEMENT OF BODY CAUSES FLUID TO FLOW PAST CUPULA
POSITION
OTOLITHS- SMALL GRAINS OF CALCIUM CARBONATE WHICH REST ON SENSORY HAIRS
UTRICLE- DETECTS SIDE TO SIDE MOVEMENT
SACCULE- DETECTS UP AND DOWN MOVEMENT