1. The Nervous System: Basic Structure Lesson 6-1

2. Objectives: Identify Parts of the Nervous System Describe the functions of the Nervous System

3. How the Nervous System Works 2 parts to the nervous system Central nervous system- brain and spinal cord Peripheral nervous system- branches of nerves that reach other parts of the body

4. How the Nervous System Works All parts of nervous system protected Brain- skull Spinal cord- vertebrae Nerves-sheathing

5. Neurons Name for a nerve cell Like a flame travels over firecracker fuse Reusable Nerves send a signal whenever they are stimulated past a minimum point Use the All-Or-None Principal- A neuron will fire completely or not at all.

6. Parts of a neuron Cell Body- Dendrites- receive impulses Axons- carries impulses away from the cell Myelin- insulates and protects the axon In multiple sclerosis, the myelin sheath is destroyed Speeds transmission of impulses Axon terminals- branch out at end of axon

8. The Neuron Connection The Space between neurons is called the synapse Chemicals called neurotransmitters carry the impulse across the gap. They can excite the next neuron or cause it to stop (inhibition)

9. The Neuron Connection Many different types of neurotransmitters Norepinephrine- involved with memory and learning Endorphines- inhibit pain Responsible for runner’s high Ach- involved with movement

10. The neuron Connection Many diseases linked to neurotransmitters Alzheimer’s Schizophrenia Parkinson’s disease Depression

11. The Neuron Connection Other nervous diseases Autism Dyslexia Multiple sclerosis Alzheimer’s disease Tourette’s syndrome Bipolar disorder

12. Neuron Activity Ascending tracts carry impulses to the brain Descending tracts carry impulses away from the brain

13. Neuron Activity Afferent or sensory neurons-relay messages from the sense organs to the brain Efferent or motor neurons-send signals from the brain to glands and muscles Interneurons- carry impulses between neurons in the body

14. Voluntary and Involuntary Activities Somatic Nervous System is voluntary You can control Autonomic Nervous System is involuntary You can’t control Can be divided into two parts

15. Autonomic Nervous System Sympathetic Deals with emergencies and strenuous activity Increases heart rate and blood pressure Parasympathetic Works to conserve energy Reduces heart rate and blood pressure Receptors tell the autonomic system what to do