UNIT 6: THE NERVOUS SYSTEM THE NERVOUS SYSTEM THE NEURON THE PERIPHERAL NERVOUS SYSTEM THE CENTRAL NERVOUS SYSTEM

THE NERVOUS SYSTEM THIS SYSTEM HELPS COORDINATE ALL THE BODIES ACTIVITIES SO THEY WORK IN HARMONY IT RECEIVES, PROCESSES, STORES, AND TRANSMITS INFORMATION FROM BOTH INSIDE AND OUTSIDE THE BODY CENTRAL SYSTEM: - BRAIN - SPINAL CORD PERIPHERAL SYSTEM: - NERVES - SENSORY RECEPTORS

THE NEURON 100 BILLION NEURONS (ON AVERAGE) ALSO CALLED “NERVE CELLS” IT IS A SPECIALIZED NERVE CELL IN THE NERVOUS SYSTEM THAT RECEIVES AND TRANSMITS MESSAGES MADE UP OF 4 PARTS DENDRITES CELL BODY (which contains the nucleus) AXON AXON TERMINALS

THE NEURON ROLE OF NEURONS: TO PICK UP STIMULI TRANSFORM THEM INTO NERVE IMPULSES TRANSMIT THESE IMPULSES STIMULUS: anything that can be perceived by a living organism and that can trigger a reaction. Sound, light, heat, electrical shocks, odours, hormones are all examples of stimuli. NERVE IMPULSE: an electrical signal transmitted by a neuron SYNAPSE: the transition zone between two neurons that allows a nerve impulse to be transmitted NERVE: a structure that helps transmit information between the central nervous system and various regions of the body

TRANSMISSION OF NERVE IMPULSES THE NEURON CHARACTERISTICS CAN BE STIMULATED: IT REACTS TO A STIMULUS BY CHANGING INTO AN ELECTRICAL SIGNAL (NERVE IMPULSE) CONDUCTIVE. TRANSMITS NERVE IMPULSE FROM NEURON TO ANOTHER UNTIL IT REACHES TARGET CONSUMES A GREAT DEAL OF OXYGEN AND GLUCOSE. CAN ONLY SURVIVE A FEW MINUTES WITHOUT OXYGEN CAN LIVE MORE THAN 100 YEARS. PEOPLE KEEP THE SAME NEURONS THEIR ENTIRE LIFE CANNOT REPRODUCE ITSELF, CANNOT BE REPLACED IF DESTROYED TRANSMISSION OF NERVE IMPULSES DENDRITES OF A NEURON RECEIVE MESSAGES OR STIMULI AND TRANSFORM THEM INTO NERVE IMPULSES THE NERVE IMPULSES ARE THEN TRANSMITTED ALONG AXONS TO THE AXON TERMINALS NERVE IMPULSES TRAVEL FROM ONE NEURON TO ANOTHER VIA NEUROTRANSMITTERS SECRETED BY AXON TERMINALS ACROSS A NARROW SPACE OR TRANSMISSION ZONE (SYNAPSE), BETWEEN TWO NEURONS.

THE PERIPHERAL NERVOUS SYSTEM CONNECTS DIFFERENT PARTS OF THE BODY TO THE CENTRAL NERVOUS SYSTEM INTERNAL/EXTERNAL MESSAGES SENSORY RECEPTORS: PICK UP STIMULI AND TRANSFORMS THEM INTO NERVE IMPULSES 2 TYPES OF NERVES: sensory and motor SENSORY NERVES: (5 SENSES + OTHERS) TRANSMIT INFORMATION, THE FORM OF NERVE IMPULSES FROM THE SENSORY RECEPTORS TO THE CENTRAL NERVOUS SYSTEM MOTOR NERVES:(MUSCLES + OTHERS) TRANMSIT IMPULSES FROM THE CENTRAL NERVOUS SYSTEM TO THE MUSCLES IN ORDER TO PRODUCE VOLUNTARY AND INVOLUNTARY MOVEMENTS

THE CENTRAL NERVOUS SYSTEM BRAIN: composed of the parts of the central nervous system located in the cranium CEREBRUM CEREBELLUM BRAIN STEM SPINAL CORD: the nervous system organ that carries information from/to the various parts of the body to/from the brain. It is also the reflex center SPINAL NERVES VERTABRAE

CEREBRUM COMMAND CENTER FOR ALL VOLUNTARY MOVEMENTS INTERPRETATION OF THE SENSES INTELLIGENCE CENTER FOR EMOTIONS DIVIDED INTO TWO HEMISPHERES (RIGHT / LEFT) RIGHT: CONTROLS THE LEFT SIDE OF THE BODY LEFT: CONTROLS THE RIGHT SIDE OF THE BODY DIVIDED INTO 4 LOBES FRONTAL, PARIETAL, OCCIPITAL, TEMPORAL OUTER LAYER – CEREBRAL CORTEX (GREY MATTER) - Muscle control, sensory perception, memory, speech INNER LAYER – WHITE MATTER - System connectedness

CEREBRUM FUNCTIONS FUNCTION DESCRIPTION EXAMPLE CONTROLS VOLUNTARY MOVEMENTS MOTOR CONTROL SENDS OUT NERVE IMPULSE TO STIMULATE MUSCLES TO CONTRACT Stretching Muscle use Walking Grasping INTERPRETS MESSAGES PICKED UP BY SENSES WHEN SENSES DETECT EXTERNAL STIMULUS THIS REGION INTERPRETS IMPULSE AND REACTS Tactile reaction Smelling Reaction to light CONTROLS INTELLIGENCE PROBLEM SOLVING, READING, REASONING:ANY ACTIVITY ASSOCIATED WITH INTELLIGENCE Thinking Reflection Reasoning CONTROLS EMOTIONS MANAGES EMOTIONS JOY, SAD, FEAR, ANGER, ETC Laughing Crying REGULATES PHYSIOLOGICAL FUNCTIONS HYPOTHALAMUS IS RESPONSIBLE FOR HUNGER, THIRST, ALERTNESS AND TEMPERATURE REGULATION. ALSO CONTROLS THE PITUITARY GLAND hot/cold Consciousness Sweating

CEREBELLUM THE CENTER FOR BALANCE AND MOVEMENT COORDINATION EXAMPLES: POSTURE DANCE, RUN MOTION SICKNESS, VERTIGO SPEAK DEXTERITY (PLAY PIANO)

BRAIN STEM THE CONTROL CENTER OF INTERNAL STIMULI AS WELL AS INVOLUNTARY MOVEMENT EXAMPLES: INTERNAL MUSCLES (DIGESTIVE SYSTEM) TWITCHING SPASMS RESPIRATION BLINKING

THE SPINAL CORD NERVOUS SYSTEM ORGAN THAT CARRIES INFORMATION FROM THE VARIOUS PARTS OF THE BODY TO THE BRAIN (AND VISE VERSA). THE REFLEX CENTER PROTECTED BY VERTEBRAE (BACK BONE) REFLEX: A RAPID AND INVOLUNTARY RECTION TO A STIMULUS (GOOSE BUMPS) REFLEX ARC: PATH TAKEN BY A NERVE IMPULSE DURING A RELFEX