THE SENSES

THE SENSES

• SENSORY INPUTS BECOME SENSATIONS AND PERCEPTIONS IN THE BRAIN– SENSATION• AN AWARENESS OF SENSORY STIMULI

– PERCEPTION• A MEANINGFUL INTERPRETATION OR CONCIOUS

UNDERSTANDING OF SENSORY DATA

THE SENSES

• SENSORY RECEPTOR CELLS CONVERT STIMULI INTO ELECTRICAL ENERGY– SENSORY TRANSDUCTION

• CELL CONVERTS A STIMULUS INTO AN ELECTRICAL SIGNAL

– RECEPTOR POTENTIAL• GRADED CHANGE IN MEMBRANE POTENTIAL

– SENSORY ADAPTATION• THE TENDENCY OF SENSORY RECEPTOR CELLS TO

BECOME LESS SENSITIVE WHEN THEY ARE STIMULATED REPEATEDLY

THE SENSES

• SPECIALIZED SENSORY RECEPTORS DETECT FIVE CATEGORIES OF STIMULI– FIVE RECEPTORS• PAIN RECEPTORS

– RESPOND TO EXCESS HEAT, PRESSURE, DANGEROUS CHEMICALS

• THERMORECEPTORS– DETECT HOT OR COLD

THE SENSES

• SPECIALIZED SENSORY RECEPTORS DETECT FIVE CATEGORIES OF STIMULI– FIVE RECEPTORS• MECHANORECEPTORS

– DETECT TOUCH, PRESSURE, STRETCHING, MOTION AND SOUND

THE SENSES

• SPECIALIZED SENSORY RECEPTORS DETECT FIVE CATEGORIES OF STIMULI– FIVE RECEPTORS• CHEMORECEPTORS

– ATTUNED TO CHEMICALS

THE SENSES

• SPECIALIZED SENSORY RECEPTORS DETECT FIVE CATEGORIES OF STIMULI– FIVE RECEPTORS• ELECTROMAGNETIC RECEPTORS

– SENSITIVE TO ENERGY OF VARIOUS WAVELENGTHS

– EX. PHOTORECEPTORS

THE SENSES

• THREE DIFFERENT TYPES OF EYES HAVE EVOLVED AMONG INVERTEBRATES– 3 TYPES• EYE CUP• COMPOUND EYE

– MANY TINY LIGHT-DETECTING UNITS

• SINGLE-LENS EYE– SIMILAR TO CAMERA

THE SENSES

• VERTEBRATES HAVE SINGLE-LENS EYES

THE SENSES

• VERTEBRATES HAVE SINGLE-LENS EYES– SCLERA– CORNEA– CHOROID

• IRIS

– PUPIL– LENS– RETINA– VITREOUS HUMOR and AQUEOUS HUMOR– CONJUCTIVA

THE SENSES

• TO FOCUS, A LENS CHANGES POSITION OR SHAPE– MUSCLES ATTACHED TO THE CHOROIDS CHANGE

THE SHAPE OF THE LENS; FOCUSING LIGHT APPROPRIATELY

THE SENSES

THE SENSES

• ARTIFICIAL LENSES OR SURGERY CAN CORRECT FOCUSING PROBLEMS– 3 COMMON PROBLEMS• NEARSIGHTEDNESS (MYOPIA)

– EYEBALL TOO LONG

• FARSIGHTEDNESS (HYPEROPIA)– EYEBALL TOO SHORT

• ASTIGMATISM– MISSHAPEN LENS OR CORNEA

THE SENSES

• OUR PHOTORECEPTOR CELLS ARE RODS AND CONES– CONES• STIMULATED BY BRIGHT LIGTH AND CAN DISTINGUISH

COLOR; DO NOT FUNCTION AT NIGHT• PHOTOPSINS

– VISUAL PIGMENTS THAT ABSORB BRIGHT, COLORED LIGHT

THE SENSES

• OUR PHOTORECEPTOR CELLS ARE RODS AND CONES– RODS• EXTREMELY SENSITIVE TO LIGHT AND ENABLE US TO

SEE IN DIM LIGHT AT NIGHT, THOUGH ONLY IN SHADES OF GRAY• RHODOPSINS

– VISUAL PIGMENT THATCAN ABSORB DIM LIGHT

THE SENSES

• THE EAR CONVERTS AIR PRESSURE WAVES INTO ACTION POTENTIALS THAT ARE PERCEIVED AS SOUND

THE SENSES

• THE EAR CONVERTS AIR PRESSURE WAVES INTO ACTION POTENTIALS THAT ARE PERCEIVED AS SOUND– OUTER EAR COLLECTS SOUNDWAVES TO EAR DRUM

• PINNA “EAR”; FLAP-LIKE STRUCTURE• AUDITORY CANAL

– EARDRUM SHEET OF TISSUE THAT SEPARATES OUTER EAR FROM MIDDLE EAR

– MIDDLE EAR• EARDRUM; HAMMER, ANVIL, STIRRUP, OVAL WINDOW

THE SENSES

• THE EAR CONVERTS AIR PRESSURE WAVES INTO ACTION POTENTIALS THAT ARE PERCEIVED AS SOUND– INNER EAR• CONTAINS COCHLEA

– THE ACTUAL HEARING ORGAN

THE SENSES

• THE INNER EAR HOUSES OUR ORGANS OF BALANCE– SEMICIRCULAR CANAL

• DETECT CHANGES IN THE HEAD’S RATE OF ROTATION OR ANGULAR MOVEMENT

– UTRICLE AND SACCULE HAIR CELLS THAT DETECT THE POSITIONOF THE HEADWITH RESPECTTO GRAVITY

THE SENSES

• WHAT CAUSES MOTION SICKNESS?– CONFLICTING SIGNALS FROM THE EYES AND

INNER EAR’S BALANCE MECHANISM– SPIN AROUND OVER AND OVER, THEN SUDDENLY

STOP…WHAT HAPPENS?!?!?!?

THE SENSES

• ODOR AND TASTE RECEPTORS DETECT CATEGORIES OF CHEMICALS

THE SENSES

• REVIEW: THE CENTRAL NERVOUS SYSTEM COUPLES STIMULUS WITH RESPONSE– NERVOUS SYSTEM LINKS STIMULUS RECEPTION

WITH RESPONSE• STIMULI RECEPTORS SENSORY NEURONS CNS

INTEGRATION MOTO NEURON EFFECTOR RESPONSE

– REFLEX ARC

THE SENSES

• WHAT ABOUT OUR MUSCLES??• SKA-DOOSH!!