Download THE HUMAN BODY

THE NERVOUS AND
ENDOCRINE SYSTEMS
THE NERVOUS SYSTEM
• THE NERVOUS SYSTEM CONTROLS THE
BODY’S ACTIVITIES
• IT RECEIVES AND SENDS OUT
INFORMATION ABOUT ACTIVITIES WITHIN
THE BODY
• MONITORS AND RESPONDS TO CHANGES
IN THE ENVIRONMENT
STIMULI
• THE CONSTANT CHANGES TAKING
PLACE AROUND YOU
– INVOLUNTARY – NOT UNDER YOUR
CONTROL
– VOLUNTARY – UNDER YOUR CONTROL
REFLEX
NEURON
• MESSAGE-CARRYING CELL
• BASIC UNIT STRUCTURE OF THE
NERVOUS SYSTEM
• UNLIKE MOST OTHER CELLS – IT
CANNOT BE REPLACED
PARTS OF A NEURON
CELL BODY – LARGEST PART –
CONTAINS THE NUCLEUS WHICH
CONTROLS ALL ACTIVITIES OF THE
CELL
• DENDRITE – CARRIES MESSAGES TO
THE CELL BODY OF THE NEURON
• AXON – CARRIES MESSAGES AWAY
FROM THE CELL BODY
– CAN BE 1 MILLIMETER TO MORE THAN
1 METER LONG
• AXON TERMINAL – FEATHERLIKE
FIBERS AT THE END OF THE AXON
– PASS MESSAGE TO THE DENDRITES OF
OTHER NEURONS
TYPES OF NEURONS
• RECEPTORS – RECEIVE
INFORMATION FROM
SURROUNDINGS
• SENSORY – MESSAGES TRAVEL FROM
RECEPTORS TO SPINAL CORD AND
BRAIN THROUGH THESE
• MOTOR – MESSAGES FROM BRAIN
OR SPINAL CORD ARE SENT TO
MUSCLE OR GLAND
• EFFECTOR – MUSCLE OR GLAND
STIMULATED BY MOTOR NEURON
NERVE IMPULSE
• THE PATH OF THE MESSAGE
– ELECTRICAL ALONG NEURON
– 120 METER PER SECOND
• SYNAPSE – TINY GAP BETWEEN
NEURONS
– IMPULSE FERRIED ACROSS BY A
CHEMICAL SIGNAL
SYNAPSE
DIVISIONS OF THE
NERVOUS SYSTEM
• CENTRAL NERVOUS SYSTEM – BRAIN
AND SPINAL CORD
• PERIPHERAL NERVOUS SYSTEM –
ALL NERVES FOUND OUTSIDE THE
CENTRAL NERVOUS SYSTEM
THE CENTRAL NERVOUS
SYSTEM
• CAN DO MANY THINGS AT ONE TIME
• ACTIVITIES ARE COMPLEX
– INTERPRET INFORMATION FROM ALL
PARTS OF THE BODY
– ISSUE COMMANDS TO THE SAME PARTS
PATH OF IMPULSE
THE BRAIN
• MAIN CONTROL CENTER OF THE
CENTRAL NERVOUS SYSTEM
• TRANSMITS AND RECEIVES
MESSAGES THROUGH THE SPINAL
CORD
• GRAY MATERIAL – CELL BODIES OF
BILLIONS OF NEURONS
• WHITE MATERIAL – UNDERNEATH –
BUNDLES OF AXONS
• MASS OF BRAIN – 1.4 KILOGRAMS
• SKULL PROTECTS THE BRAIN
• WRAPPED IN THREE LAYERS OF
CONNECTIVE TISSUE WHICH NOURISH
AND PROTECT IT
– INNER LAYER – CLINGS TO SURFACE OF THE
BRAIN AND FOLLOWS IT’S MANY FOLDS
– MIDDLE LAYER – WATERY FLUID THAT
CUSHIONS AGAINST SUDDEN IMPACT
– OUTER LAYER – THICKER AND TOUGHER
THAN THE OTHER TWO LAYERS
PARTS OF THE BRAIN
CEREBRUM
• LARGEST AND MOST NOTICIBLE
• LINED WITH DEEP WRINKLED
GROOVES – INCREASE AREA
ALLOWING FOR MORE ACTIVITIES
TO OCCUR
• LEARNING, INTELLIGENCE, AND
JUDGEMENT
• CONTROLS VOLUNTARY ACTIVITIES
OF THE BODY
• SHAPES ATTITUDES, EMOTIONS, AND
PERSONALITY
• DIVIDED INTO HALVES – EACH CONTROLS
A DIFFERENT KIND OF MENTAL ACTIVITY
– RIGHT – ARTISTIC
– LEFT – MATHEMATICAL
– EACH CONTROLS THE OPPOSITE SIDE OF THE
BODY
CEREBELLUM
• LOCATED TO THE REAR AND BELOW
THE CEREBRUM
• COORDINATES ACTIONS OF
MUSCLES
• MAINTAINS BALANCE
MEDULLA OBLONGATA
• LOCATED BELOW THE CEREBELLUM
• CONNECTS BRAIN TO SPINAL CORD
• CONTROLS INVOLUNTARY ACTIONS
MEDULLA OBLONGATA
SPINAL CORD
• RUNS THE ENTIRE LENGTH OF THE NECK
AND BACK
• CONNECTS THE BRAIN WITH THE REST OF
THE NERVOUS SYSTEM THROUGH A
SERIES OF 31 PAIRS OF NERVES
– THESE NERVES CARRY IMPULSES TO AND
FROM THE SPINAL CORD
REFLEX
• A SIMPLE RESPONSE TO STIMULUS
• AUTOMATIC – NERVE IMPULSES
TRAVEL ONLY TO THE SPINAL CORD
BYPASSING THE BRAIN
THE PERIPHERAL NERVOUS
SYSTEM
• LINK BETWEEN THE CENTRAL
NERVOUS SYSTEM AND THE REST OF
THE BODY
• CONSISTS OF 43 PAIRS OF NERVES
THAT ARISE FROM THE BRAIN AND
SPINAL CORD AND LEAD TO ORGANS
THROUGHOUT THE BODY
MANY ARE UNDER DIRECT CONTROL
OF THE CONSCIOUS MIND
AUTONOMIC NERVOUS
SYSTEM
• NOT UNDER CONTROL OF THE
CONSCIOUS MIND
• CONTROLS BODY’S ACTIVITIES THAT
ARE INVOLUNTARY
– CONTRACTIONS OF THE HEART,
DIGESTIVE SYSTEM, ETC.
• TWO GROUPS
– TRIGGERS AN ACTION
– STOPS AN ACTION
THE SENSES
• STRUCTURES THAT CARRY
MESSAGES ABOUT YOUR
SURROUNDINGS TO THE CENTRAL
NERVOUS SYSTEM
• MOST RESPOND TO STIMULI FROM
BODY’S EXTERNAL ENVIRONMENT
OTHERS KEEP TRACK OF
ENVIRONMENT INSIDE THE BODY
• SENSE ORGANS RESPOND TO LIGHT,
SOUND, HEAT, PRESSURE, AND
CHEMICALS
• THEY DETECT CHANGES IN BODY
POSITION
VISION
• EYES ARE DESIGNED TO FOCUS LIGHT
RAYS TO PRODUCE IMAGES OF OBJECTS
• THE BRAIN RECEIVES AND INTERPRETS
THE MESSAGES THAT CORRESPOND TO
THESE IMAGES
• VISION CENTER – BACK OF THE BRAIN
EYE
• EYEBALL – SHAPED LIKE A BALL
• SLIGHTLY LONGER THAN WIDE
• COMPOSED OF THREE LAYERS OF
TISSUE
OUTER LAYER
• SCLERA – WHITE OF THE EYE
• CORNEA – TRANSPARENT AREA OF
SCLERA
– CENTER FRONT OF EYEBALL
– PART THROUGH WHICH LIGHT ENTERS
– INSIDE CHAMBER IS FILLED WITH
FLUID (AQUEOUS HUMOR)
MIDDLE LAYER
• CHROID – CONTAINS BLOOD VESSELS
• IRIS – BACK OF CHAMBER
– COLORED PORTION OF EYE
• PUPIL – MIDDLE OF IRIS
– SMALL OPENING
– SIZE OF OPENING IS CONTROLLED BY MUSCLE
OF THE IRIS
• LENS – BEHIND THE IRIS
– FOCUSES LIGHT RAYS COMING INTO
THE EYE
– SMALL MUSCLE ENABLES IT TO
CHANGE SHAPE TO SEE CLOSE OR FAR
• RELAXED – FLATTENS LENS – SEE FAR
• CONTRACT – NORMAL – SEE CLOSE
INNER LAYER
• VITREOUS HUMOR –JELLYLIKE
FLUID BEHIND LENS
• RETINA – BACK SURFACE OF EYE
– 130 MILLION LIGHT-SENSITIVE
RECEPTORS
• RODS – DIM LIGHT BUT NOT COLORS
• CONES – COLOR BUT STOP WORKING
IN DIM LIGHT
THE RETINA
• BOTH RODS AND CONES PRODUCE
NERVE IMPULSES THAT TRAVEL
FROM THE RETINA TO THE OPTIC
NERVE
• FROM THE OPTIC NERVE THE
IMPULSES TRAVEL TO THE VISUAL
CENTER OF THE BRAIN
GLAUCOMA
• THE BRAIN INTERPRETS THE
IMPULSE
• THE IMAGE ON THE RETINA IS
UPSIDE DOWN – THE BRAIN TURNS
IT RIGHT SIDE UP
• THE BRAIN COMBINES THE TWO
IMAGES FROM THE TWO EYES TO
CREATE A 3-D IMAGE
HEARING AND BALANCE
• SOUND SOURCES VIBRATE THROUGH THE
AIR IN WAVES
• HEARING BEGINS WHEN THE SOUND
WAVES ENTER THE EXTERNAL EAR
• THE FUNNELLIKE SHAPE OF THE
EXTERNAL EAR ENABLES IT TO GATHER
SOUND WAVES
EARDRUM
• TIGHTLY STRETCHED MEMEBRANE THAT
SEPARATES THE EAR CANAL FROM THE
MIDDLE EAR
• AS SOUND WAVES STRIKE THE EARDRUM
IT VIBRATES
• VIBRATIONS FROM THE EARDRUM ENTER
THE MIDDLE EAR
MIDDLE EAR
• COMPOSED OF THE THREE
SMALLEST BONES IN THE BODY
– HAMMER
– ANVIL
– STIRRUP
• THE STIRRUP VIBRATES AGAINST A
THIN MEMEBRANE COVERING THE
OPENING INTO THE FLUID-FILLED
INNER EAR
• VIBRATIONS PASS THROUGH THE
FLUID AND ARE CHANNELED INTO A
SNAIL-SHAPED TUBE CALLED THE
COCHLEA
• THE COCHLEA CONTAINS NERVES
THAT ARE STIMULATED BY THE
VIBRATIONS
• THE NERVES PRODUCE AN IMPULSE
THAT IS CARRIED FROM THE
COCHLEA TO THE BRAIN BY THE
AUDITORY NERVE
• ONCE IN THE BRAIN, THE IMPULSE IS
INTERPRETED AND YOU HEAR
BALANCE
• SEMICIRCULAR CANALS – RESPONSIBLE
FOR BALANCE
• THREE TINY CANALS LOCATED WITHIN
THE INNER EAR JUST ABOVE THE
COCHLEA
– TINY SACS FILLED WITH FLUID AND ARE
LINED WITH HAIRLIKE CELLS
– THESE HAIRLIKE CELLS ARE EMBEDED
IN A JELLYLIKE SUBSTANCE THAT
CONTAINS TINY GRAINS CALLED
HEARING STONES
– WHEN YOUR HEAD MOVES, THE
HEARING STONES ROLL BACK AND
FORTH BENDING THE HAIRLIKE CELLS
– THE CELLS RESPOND BY SENDING
NERVE IMPULSES TO THE BRAIN
– THE BRAIN SIGNALS MUSCLES TO
CONTRACT IF IT INTERPRETS THE
SIGNAL TO MEAN THAT YOU ARE
LOSING YOUR BALANCE
SMELL
• CHEMICALS AFFECT THE SENSE
RECEPTORS IN YOUR NOSE
• THEY PRODUCE IMPULSES THAT ARE
CARRIED TO YOUR BRAIN AND
INTERPRETED
TASTE
• TASTE IS ALSO A CHEMICAL SENSE
• CHEMICALS ARE CARRIED IN
LIQUIDS IN YOUR MOUTH
• TASTE BUDS ON YOUR TONGUE ARE
THE CHEMICAL RECEPTORS
– BITTER, SOUR, SWEET, AND SALT
– COMBINED WITH 80 BASIC ODORS
PRODUCE FLAVORS
TOUCH
• THE SENSE OF TOUCH IS FOUND IN ALL
AREAS OF THE SKIN
• NEAR THE SURFACE ARE TOUCH
RECEPTORS THAT ALLOW YOU TO FEEL
THE TEXTURES OF OBJECTS
• LOCATED DEEPER WITHIN THE SKIN ARE
RECEPTORS THAT SENSE PRESSURE
• THERE ARE ALSO THE RECEPTORS
TO HEAT AND COLD AND ARE
SCATTERED DIRECTLY BELOW THE
SURFACE
• PAIN RECEPTORS ARE FOUND ALL
OVER THE SKIN
EXOCRINE GLANDS
• GIVE OFF CHEMICALS THROUGH
DUCTS OR TUBES INTO NEARBY
ORGANS
• DO NOT PRODUCE HORMONES
• PRODUCE TEARS, SWEAT, OIL, AND
DIGESTIVE JUICES
ENDOCRINE SYSTEM
• GLANDS THAT PRODUCE CHEMICAL
MESSENGERS CALLED HORMONES
• RELEASED DIRECTLY INTO THE
BLOOD
HORMONES
• TURN ON OR OFF
• SPEED UP OR SLOW DOWN DIFFERENT
ACTIVITIES OF ORGANS
• DELIVERED BY CIRCULATORY SYSTEM
• TISSUE CELLS ARE PROGRAMMED TO
ACCEPT CERTAIN HORMONES AND REJECT
OTHERS
THE HUMAN BODY HAS EIGHT
ENDOCRINE GLANDS THAT RELEASE
DIFFERENT HORMONES
HYPOTHALAMUS
• LOCATED AT BASE OF BRAIN
• MAJOR LINK BETWEEN THE
NERVOUS SYSTEM AND ENDOCRINE
SYSTEM
• CONTROLS THE SEVEN OTHER
ENDOCRINE GLANDS
• MESSAGES TRAVELING TO AND
FROM THE BRAIN PASS THROUGH
THE HYPOTHALAMUS
PITUITARY
• CENTER OF SKULL BEHIND BRIDGE OF
NOSE
• TALKS TO HYPOTHALAMUS THROUGH
CHEMICALS AND NERVE IMPULSES
• BLOOD PRESSURE, GROWTH,
METABOLISM, SEXUAL DEVELOPMENT,
AND REPRODUCTION
THYMUS
• BEHIND STERNUM
• GETS SMALLER AS YOU GROW – BY
ADULTHOOD – SIZE OF THUMB
• DEVELOPMENT OF IMMUNE SYSTEM
• INFANCY – PRODUCES WHITE BLOOD
CELLS
THYROID
• IN NECK
• CONTROLS HOW QUICKLY FOOD IS
BURNED UP BY THE BODY
(METABOLISM)
PARATHYROIDS
• EMBEDED IN THYROID
• CONTROLS THE LEVEL OF CALCUIM
IN THE BLOOD
ADRENALS
• ON TOP OF KIDNEYS
• REACTION TO A DANGEROUS
SITUATION
– PRODUCES ADRENALINE – THE BODY’S
EMERGENCY ACTION TEAM
ADRENAL GLAND
PANCREAS
• LOCATED BY SMALL INTESTINE
• INSULIN – KEEPS BLOOD SUGAR
LEVELS UNDER CONTROL
• HELPS THE BODY ABSORB IT AND USE IT
FOR ENERGY
• CHANGES SUGAR INTO GLYCOGEN FOR
STORAGE
• DIABETES MELLITUS – DROP IN
INSULIN PRODUCTION
– INSULIN PRODUCED BY SMALL GROUP
OF CELLS CALLED ISLETS OF
LANGERHAUS
– ISLETS ALSO PRODUCE GLUCAGON –
OPPOSITE EFFECT OF INSULIN
• INCREASES BLOOD SUGAR LEVEL
OVARIES
FEMALE REPRODUCTIVE GLANDS
TESTES
MALE REPRODUCTIVE GLANDS
NEGATIVE FEEDBACK
MECHANISM
• AUTOMATICALLY CONTROLS THE
LEVELS OF HORMONES IN THE BODY
• PRODUCTION OF A HORMONE IS
CONTROLLED BY THE AMOUNT OF
ANOTHER HORMONE IN THE BLOOD
THEREBY KEEPING THE BODY’S
INTERNAL ENVIRONMENT STABLE
• EXAMPLE:
– THE PITUITARY IS SENTITIVE TO
THYROXINE (PRODUCED BY THE
THYROID)
• IF TOO LOW – TSH (THYROID STIMULATING
HORMONE) IS RELEASED