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