NERVOUS SYSTEM
NERVOUS SYSTEM NERVOUS SYSTEM • NERVOUS SYSTEMS RECEIVE SENSORY INPUT, INTEPRET IT, AND SENT OUT APPROPRIATE COMMANDS – NERVOUS SYSTEMS • MOST INTRICATELY ORGANIZED DATA PROCESSING SYSTEM ON EARTH – NEURON • FUNCTIONAL UNIT; SPECIALIZED NERVE CELL FOR CARRYING SIGNALS FROM ONE LOCATION IN THE BODY TO ANOTHER NERVOUS SYSTEM • NERVOUS SYSTEMS RECEIVE SENSORY INPUT, INTEPRET IT, AND SENT OUT APPROPRIATE COMMANDS – NERVOUS SYSTEM HAS 3 INTERCONNECTED FUNCTIONS NERVOUS SYSTEM • NERVOUS SYSTEMS RECEIVE SENSORY INPUT, INTEPRET IT, AND SENT OUT APPROPRIATE COMMANDS – NERVOUS SYSTEM HAS 3 INTERCONNECTED FUNCTIONS • SENSORY INPUT CONDUCTION OF SIGNALS FROM SENSORY RECEPTORS TO INTEGRATION CENTERS • INTEGRATION INTERPRETATION OF THE SENSORY SIGNALS AND THE FORMULATION OF RESPONSES • MOTOR OUTPUT THE CONDUCCTION OF SIGNALS FROM THE INTEGRATION CENTERS TO EFFECTORS – MUSCLES OR GLANDS THAT PERFORM BODY FUNCTIONS NERVOUS SYSTEM • NERVOUS SYSTEMS HAVE TWO MAIN DIVISIONS – CENTRAL NERVOUS SYSTEM (CNS) • WHERE MOST INTEGRATION OCCURS; CONSISTS OF THE BRAIN AND SPINAL CORD (IN VERTEBRATES) – PERIPHERAL NERVOUS SYSTEM (PNS) • MADE UP OF COMMUNICATION LINES CALLED NERVES THAT CARRY SIGNALS IN AND OUT OF THE CNS • NERVE – A CABLE-LIKE BUNDLE OF NEURON EXTENSIONS TIGHTLY WRAPPED IN CONNECTIVE TISSUE • GANGLIA – CLUSTERS OF NEURON CELL BODIES IN THE NERVES NERVOUS SYSTEM • THREE FUNCTIONAL TYPES OF NEURONS NERVOUS SYSTEM • THREE FUNCTIONAL TYPES OF NEURONS – SENSORY NEURONS – INTERNEURONS – MOTOR NEURONS NERVOUS SYSTEM • NEURONS ARE THE FUNCTIONAL UNITS OF NERVOUS SYSTEMS – STRUCTURE OF A NEURON NERVOUS SYSTEM • STRUCTURE OF A NEURON – CELL BODY HOUSES THE NUCLEUS AND OTHER ORGANELLES • DENDRITES SHORT, MANY BRANCHES; RECEIVE INCOMING MESSAGES AND DIRECT THEM TOWARD CELL BODY • AXON USUALLY A SINGLE FIBER; CONDUCTS SIGNAL TOWARDS ANOTHER NEURON OR EFFECTOR NERVOUS SYSTEM • STRUCTURE OF A NEURON – SUPPORTING CELLS PROTECT, INSULATE, AND REINFORCE THE NEURONS • SHCHWANN CELLS – MYELIN SHEATH – NODES OF RANVIER » INCREASE SPEED AT WHICH SIGNAL TRAVELS NERVOUS SYSTEM • STRUCTURE OF A NEURON – SYNAPTIC KNOB (TERMINAL BRANCH) • ENDS THE NEURON; RELAYS SIGNALS TO ANOTHER NEURON OR EFFECTOR – SYNAPSE • THE JUNCTION, OR RELAY POINT, BETWEEN TWO NEURONS OR BETWEEN A NEURON AND AN EFFECTOR CELL NERVOUS SYSTEM • A NEURON MAINTAINS A MEMBRANE POTENTIAL ACROSS ITS MEMBRANE – RESTING POTENTIAL • THE VOLTAGE ACROSS THE PLASMA OF A RESTING NEURON – SODIUM-POTASSIUM (NA+ / K+) PUMPS • ACTIVELY TRANSPORT NA+ OUT OF THE CELL AND K+ IN NERVOUS SYSTEM • A NERVE SIGNAL BEGINS AS A CHANGE IN THE MEMBRANE POTENTIAL NERVOUS SYSTEM • A NERVE SIGNAL BEGINS AS A CHANGE IN THE MEMBRANE POTENTIAL – STIMULUS • ANY FACTOR THAT CAUSES A NERVE SIGNAL TO BE GENERATED – ACTION POTENTIAL • THE TECHNICAL NAME FOR THE NERVE SIGNAL – THRESHOLD POTENTIAL • THE MINIMUM CHANGE THAT MUST OCCUR TO GENERATE AN ACTION POTENTIAL – **CYCLIC PROCESS** NERVOUS SYSTEM • THE ACTION POTENTIAL PROPAGATES ITSELF ALONG THE NEURON – ALL-OR-NONE EVENTS – DIFFERENT INTENSITIES RESULT FROM FREQUENCY OF POTENTIALS NERVOUS SYSTEM • NEURONS COMMUNICATE AT SYNAPSES – SYNAPSE • THE JUNCTION, OR RELAY POINT, BETWEEN TWO NEURONS OR BETWEEN A NEURON AND AN EFFECTOR CELL – SYNAPSES CAN BE EITHER ELECTRICAL OR CHEMICAL • ELECTRICAL SYNAPSES TRANSFER SIGNALS FASTER NERVOUS SYSTEM • NEURONS COMMUNICATE AT SYNAPSES – SYNAPSE • THE JUNCTION, OR RELAY POINT, BETWEEN TWO NEURONS OR BETWEEN A NEURON AND AN EFFECTOR CELL – SYNAPSES CAN BE EITHER ELECTRICAL OR CHEMICAL • CHEMICAL SYNAPSES HAVE A NARROW GAP CALLED A SYNAPTIC CLEFT NERVOUS SYSTEM • NEURONS COMMUNICATE AT SYNAPSES – SYNAPSE • THE JUNCTION, OR RELAY POINT, BETWEEN TWO NEURONS OR BETWEEN A NEURON AND AN EFFECTOR CELL – SYNAPSES CAN BE EITHER ELECTRICAL OR CHEMICAL • SYNAPTIC CLEFT – SEPARATES SYNAPTIC KNOBS FROM RECEIVING NEURON NERVOUS SYSTEM • CHEMICAL SYNAPSES MAKE COMPLEX INFORMATION PROCESSING POSSIBLE – MULTIPLE SIGNALS CAN BE SENT TO THE SAME RECEIVING NEURON – NEUROTRANSMITTER • CHEMICAL SIGNAL • NERVOUS SYSTEM EQUIVALENT TO A HORMONE NERVOUS SYSTEM • A VARIETY OF SMALL MOLECULES FUNCTION AS NEUROTRANSMITTERS – ACETYLCHOLINE • IMPORTANT IN THE BRAIN; MAY BE EXCITATORY OR INHIBITORY – BIOGENIC AMINES • NITROGEN CONTAINING NEUROTRANSMITTERS DERIVED FROM AMINO ACIDS • EXAMPLES INCLUDE EPINEPHRINE, NOREPINEPHRINE, SEROTONIC, DOPAMINE – ENDORPHINS ARE PEPTIDES THAT DECREASE PAIN PERCEPTION – DISSOLEVD GASES LIKE NO (NITROUS OXIDE) ACT AS NEUROTRANSMITTERS NERVOUS SYSTEM • MANY DRUGS ACT AT CHEMICAL SYNAPSES – EFFECT US BY ACTING AT SYNAPSES OR CHANGING THE NEUROTRANSMITTER NERVOUS SYSTEM • NERVOUS SYSTEM ORGANIZATION USUALLY CORRELATES WITH BODY SYMMETRY NERVOUS SYSTEM • NERVOUS SYSTEM ORGANIZATION USUALLY CORRELATES WITH BODY SYMMETRY – NERVE NET • WEB-LIKE SYSTEM OF NEURONS EXTENDING THROUGHOUT THE BODY – CEPHALIZATION • CONCENTRATION OF NERVOUS SYSTEM AT HEAD END – CENTRALIZATION • THE PRESENCE OF A CNS DISTINCT FROM A PNS NERVOUS SYSTEM • VERTEBRATE NERVOUS SYSTEMS ARE HIGHLY CENTRALIZED AND CEPHALIZED NERVOUS SYSTEM • VERTEBRATE NERVOUS SYSTEMS ARE HIGHLY CENTRALIZED AND CEPHALIZED – CNS IS MADE UP OF THE SPINAL CORD AND BRAIN • SPINAL CORD – LIES INSIDE THE VERTEBRAL COLUMN, OR SPINE, RECEIVES SENSORY INFORMATION FROM THE SKIN AND MUSCLES AND INTEGRATES SIMPLE RESPONSES TO CERTAIN KINDS OF STIMULI NERVOUS SYSTEM • VERTEBRATE NERVOUS SYSTEMS ARE HIGHLY CENTRALIZED AND CEPHALIZED – CNS IS MADE UP OF THE SPINAL CORD AND BRAIN • BRAIN – MASTER CONTROL CENTER; INCLUDES HOMEOSTATIC CENTERS THAT KEEP THE BODY FUNCTIONING SMOOTHLY; SENSORY CENTERS THAT INTEGRATE DATA FROM THE SENSE ORGANS; IN HUMANS, CENTERS OF EMOTIONS AND INTELLIGENCE; ALSO SEND OUT MOTOR COMMANDS TO MUSCLES NERVOUS SYSTEM • VERTEBRATE NERVOUS SYSTEMS ARE HIGHLY CENTRALIZED AND CEPHALIZED – CNS IS MADE UP OF THE SPINAL CORD AND BRAIN • BLOOD-BRAIN BARRIER – MAINTAINS A STABLE CHEMICAL ENVIRONMENT IN THE BRAIN; ONLY ESSENTIAL NUTRIENTS AND OXYGEN PASS FREELY INTO THE BRAIN NERVOUS SYSTEM • VERTEBRATE NERVOUS SYSTEMS ARE HIGHLY CENTRALIZED AND CEPHALIZED – CNS IS MADE UP OF THE SPINAL CORD AND BRAIN • VENTRICLES AND CENTRAL CANAL – FLUID-FILLED SPACES IN BRAIN AND SPINAL CORD, RESPECTIVELY – CEREBROSPINAL FLUID » FLUID THAT CUSHIONS THE CNS AND HELPS SUPPLY IT WITH NUTRIENTS, HORMONES, AND WHITE BLOOD CELLS – MENINGES » LAYERS OF CONNECTIVE TISSUE, ALSO SUPPLY CUSHION NERVOUS SYSTEM • VERTEBRATE NERVOUS SYSTEMS ARE HIGHLY CENTRALIZED AND CEPHALIZED – CNS HAS 2 DISTINCT AREAS NERVOUS SYSTEM • VERTEBRATE NERVOUS SYSTEMS ARE HIGHLY CENTRALIZED AND CEPHALIZED – CNS HAS 2 DISTINCT AREAS • WHITE MATTER – MAINLY AXONS – WITH WHITISH MYELIN SHEATH • GRAY MATTER – MAINLY NERVE BODIES AND DENDRITES; IN MAMMALS IT IS THE AREA OF HIGHER BRAIN FUNCTION NERVOUS SYSTEM • VERTEBRATE NERVOUS SYSTEMS ARE HIGHLY CENTRALIZED AND CEPHALIZED – PNS HAS • CRANIAL NERVES – CARRY SIGNALS TO OR FROM THE BRAIN • SPINAL NERVES – CARRY SIGNALS TO OR FROM THE SPINAL CORD NERVOUS SYSTEM • THE PERIPHERAL NERVOUS SYSTEM OF VERTEBRATES IS A FUNCTIONAL HIERARCHY NERVOUS SYSTEM • OPPOSING ACTIONS OF SYMPATHETIC AND PARASYMPATHETIC NEURONS REGULATE THE INTERNAL ENVIRONMENT – AUTONOMIC NERVOUS SYSTEM HAS 2 DIVISIONS NERVOUS SYSTEM • OPPOSING ACTIONS OF SYMPATHETIC AND PARASYMPATHETIC NEURONS REGULATE THE INTERNAL ENVIRONMENT – AUTONOMIC NERVOUS SYSTEM HAS 2 DIVISIONS • PARASYMPATHETIC DIVISION – PRIMES THE BODY FOR DIGESTING FOOD AND RESTING • SYMPATHETIC DIVISION – PREPARES THE BODY FOR INTENSE, ENERGY-CONSUMING ACTIVITIES, SUCH AS FIGHTING, FLEEING, OR COMPETING IN A STRENUOUS GAME NERVOUS SYSTEM • THE VERTEBRATE BRAIN DEVELOPS FROM THREE ANTERIOR BULGES OF THE NEURAL TUBE NERVOUS SYSTEM • THE VERTEBRATE BRAIN DEVELOPS FROM THREE ANTERIOR BULGES OF THE NEURAL TUBE – 3 ANCESTRAL REGIONS • FOREBRAIN LEADS TO CEREBUM (DOMINANT PART OF FOREBRAIN) • MIDBRAIN • HINDBRAIN NERVOUS SYSTEM • THE STRUCTURE OF A LIVING SUPERCOMPUTER: THE HUMAN BRAIN NERVOUS SYSTEM • THE STRUCTURE OF A LIVING SUPERCOMPUTER: THE HUMAN BRAIN – MAJOR STRUCTURES • • • • • CEREBRUM CEREBELLUM MEDULLA OBLONGATA PONS CORPUS COLLOSUM NERVOUS SYSTEM • THE CEREBRAL CORTEX IS A MOSAIC OF SPECIALIZED, INTERACTIVE REGIONS – CEREBRAL CORTEX • ACCOUNTS FOR 80% OF BRAINS TOTAL MASS; INVOLVED IN REASONING AND MATHEMATICAL ABILITIES, LANGUAGE SKILLS, IMAGINATION, ARTISTIC TALENT, AND PERSONALITY TRAITS NERVOUS SYSTEM • THE CEREBRAL CORTEX IS A MOSAIC OF SPECIALIZED, INTERACTIVE REGIONS – LATERALIZATION • AREAS IN THE TWO HEMISPHERES BECOME SPECIALIZED FOR DIFFERENT FUNCTIONS NERVOUS SYSTEM • INJURIES AND BRAIN OPERATIONS HAVE PROVIDED INSIGHT INTO BRAIN FUNCTION – “BROKEN BRAINS” HAVE GIVEN INSIGHT INTO NORMAL BRAIN FUNCTION – LACK OF NERVES ON THE BRAIN ALLOW NEUROSURGEONS TO OPERATE AND DISCERN SPECIFIC ASPECTS OF BRAIN FUNCTION NERVOUS SYSTEM • SEVERAL PARTS OF THE BRAIN REGULATE SLEEP AND AROUSAL – RETICULAR FORMATION • SYSTEM OF NEURONS THAT EXTENDS THROUGH THE CORE OF THE BRAINSTEM; RECEIVES DATA FROM SENSORY RECEPTORS, FILTERS AND SENDS USEFUL DATA TO CEREBRAL CORTEX NERVOUS SYSTEM • SEVERAL PARTS OF THE BRAIN REGULATE SLEEP AND AROUSAL – ELECTROENCEPHALOGRAM (EEG) • MEASURES BRAIN WAVE ACTIVITY • REM SLEEP – RAPID EYE MOVEMENT – UNIQUE BRAIN-WAVE PATTERN DURING DEEP SLEEP; TIME WHEN DREAMS OCCUR NERVOUS SYSTEM • THE LIMBIC SYSTEM IS INVOLVED IN EMOTIONS, MEMORY, AND LEARNING – LIMBIC SYSTEM • INCLUDES PARTS OF THALMAMUS; HYPOTHALAMUS, PORTIONS OF CEREBRAL CORTEX; AMYGDALA AND HIPPOCAMPUS PLAY KEY ROLES IN MEMORY, LEARNING, AND EMOTION NERVOUS SYSTEM • THE LIMBIC SYSTEM IS INVOLVED IN EMOTIONS, MEMORY, AND LEARNING – LIMBIC SYSTEM • AMYGDALA – CENTRAL IN RECOGNIZING THE EMOTIONAL CONTENT OF FACIAL EXPRESSIONS AND LAYING DOWN EMOTIONAL MEMORIES • HIPPOCAMPUS – INVOLVED IN FORMATION OF MEMORIES AND THEIR RECALL NERVOUS SYSTEM • WE NEED TO SPRINKLE IN A FEW MORE PIECES OF INFO ON THE HUMAN BODY – SENSES – MUSCLES
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