The nervous system functions to receive information through the senses, store information in the brain and spinal cord, make decisions, and send responses through the body. It is composed of neurons, which are cells that transmit electrochemical signals. Information enters neurons through dendrites, is processed in the cell body, and travels down the axon through axon bulbs. At synapses, neurotransmitters are released by the axon bulb to signal the next neuron. The central nervous system includes the brain and spinal cord, while the peripheral nervous system connects the body to the CNS and controls voluntary and involuntary functions. Reflexes are rapid, unconscious responses to stimuli. Nervous system injuries like concussions and spinal cord damage can impair functions or

1. Nervous System6th Grade Science

2. I. FunctionA. Receive information (Stimulation)B. Store informationC. Make decisionsD. Send Responses to Body (Response)E. Maintain Homeostasis

3. II. NeuronA. Cell 1. Large cell body 2. Thread like projections – Dendrites 3. One large projection – Axon 4. Many small endings – Axon BulbsB. Pathway 1. Information enters through dendrites 2. Processed in cell body 3. Travels down axons 4. Exits out axon bulbs 5. Speed = 120 meters/second 6. Numbers = Many billions

4. C. Synapse 1. Axon Bulbi. Release chemical a. Neurotransmitter b. Exocytosis ii. Signal dendrite iii. Up to 10,000 links

5. III. PartsA. Central Nervous System (CNS)1. Braini. Number = 100 billion neurons ii. Parts a. Cerebrum (thought) b. Cerebellum (muscle) c. Brain Stem (life support)2. Spinal Cord (link to PNS)

6. B. Peripheral Nervous System (PNS)1.Connects body to CNS2. Partsi. Somatic Nervous Systema. Voluntary body functionsii. Autonomic Nervous System a. Involuntary body functions

7. IV. ReflexesA. Rapid Response (without knowledge) 1. Sensory Neuron Detects 2. Spinal Cord Sends Response 3. Nerves Move Muscles in hand 4. Spinal Cord Notifies Brain of action taken

8. V. InjuriesA. Concussions 1. Bruising Brain 2. Brain Pushed against skull 3. May result in death or long term damageB. Spinal Cord 1. Lack control below injured nerves 2. Result in paralysis or death

9. VI. DrugsA. Definition: Any chemical that changes behaviorB. Drug Abuse: Deliberate misuse of drug 1. Mood changes 2. Lying & Cheating 3. Forgetfulness 4. Withdrawn 5. Aggressive 6. Slurred speech

10. C. Tolerance1. Body adjusts to drug so large amounts are needed2. Overdose becomes higher risk

11. D. Addiction1. Body altered by drug2. Physical dependence on chemical3. Sever withdrawal symptoms may occur when normal body chemistry is restored

12. E. Other Effects1. Pathogens for dirty needles2. Legal problems3. School/work problems

13. F. Types of Drugs1. Depressantsi. Slow central nervous systemii. Muscles relax to point of sleep2. Stimulantsi. Speed up Central Nervous Systemii. Rapid heart rate, breathing, …3. Inhalants: Into lungs4. Hallucinogens: see or hear things not real5. Steroidsi. Increase muscle sizeii. Internal organ damageiii. Mood alteration

14. 6. Alcoholi. Absorbed directly by stomachii. Blood Alcohol Concentration (BAC) a. 0.1 BAC is 0.1% alcohol b. 0.08 BAC is legally drunkiii. Danger Every two minutes someone dead by alcoholiv. Long Term Abuse a. Mental change b. Liver Damage

15. Quiz