1. Nervous System Transmission of Nerve Signals for  Communication  Coordination and Regulation of Body Systems

2. Structure of a Neuron Cell Body (maintains cell metabolism) Dendrites (receive signals) Axon of another neuron Axon (conducts signals) Myelin Sheath (insulator) Dendrite of another neuron Axon bulb

3. Types of Neurons Receives information from environment Generates a response Carries signal between sensory and motor neurons

4. gaps in myelin sheath formed by Schwann cells axon bundle of nerve fibers

5. Transmission of Nerve Impulse Along a Neuron Involves a change in charge across the neuron’s membrane, caused by the movement of ionsInvolves a change in charge across the neuron’s membrane, caused by the movement of ions Action Potential = rapid depolarization and repolarization of membraneAction Potential = rapid depolarization and repolarization of membrane

6. Electrical Events During An Action Potential 80 40 0 -40 -80 Recorded Potential (millivolts) Time (milliseconds) Resting Potential Extracellular Fluid (uncharged) Threshold IPSP EPSP 1 2 3 Action Potential Action Potential depolarization repolarization polarized

7. Org - Resting Potential Depends on Ionic Gradients K+K+K+K+ K+K+K+K+ K+K+K+K+ K+K+K+K+ K+K+K+K+ K+K+K+K+ K+K+K+K+ Na + Cl - Inside: Potassium ions are pumped into cell Large organic molecules cannot pass through membrane Outside: Sodium ions are pumped out Chloride ions found in extra- cellular fluid Net negative charge inside neuron 2

8. Resting Potential Sodium Channel (closed) Potassium Channel (closed)

9. Action Potential 1. Sodium flows into neuron through open channel, causing depolarization 2. Potassium flows out of neuron through open channel, causing repolarization inside outside inside outside

10. Propagation of an Action Potential Along an Axon 15

11. Transmission of Nerve Impulses Between Neurons Signal is carried by neurotransmitters that diffuse across the space between neuronsSignal is carried by neurotransmitters that diffuse across the space between neurons –Synapse: junction between neurons –Synaptic cleft: space between neurons Neurotransmitters bind to receptors on next neuron, opening ion channelsNeurotransmitters bind to receptors on next neuron, opening ion channels synapse 14

12. Structure and Operation of the Synapse 1Action potential is initiated 2Action potential reaches axon bulb 3Synaptic vesicles release neurotransmitter 4Neurotransmitter binds to receptor and opens ion channel 5Action Potential can be triggered in post-synaptic cell Pre-synaptic cell Post-synaptic cell

13. Transmission Between Neurons Neurotransmitters can beNeurotransmitters can be –Stimulatory: initiate action potential AcetylcholineAcetylcholine –Inhibitory: prevent action potential DopamineDopamine After acting on the post-synaptic neuron, neurotransmitters are removed from the synaptic cleftAfter acting on the post-synaptic neuron, neurotransmitters are removed from the synaptic cleft –Acetylcholinesterase breaks down acetylcholine

14. Neurotransmitters carry signals to muscle cells to stimulate contraction. 19

15. Applying Your Knowledge Which one is responsible for A.Transmission of a nerve impulse across a synapse? B.Depolarization of a neuron’s membrane? C.Transmission of a nerve impulse along an axon? D.Repolarization of a neuron’s membrane? 1.Potassium Ions (K+) 2.Neurotransmitters 3.Sodium Ions (Na+)

16. Nervous System Organization Central Nervous System Peripheral Nervous System Brain Spinal Cord Somatic Nervous System (voluntary) Autonomic Nervous System (involuntary) Sympathetic Division (stress or activity) Parasympathetic Division (maintenance or relaxation)

17. Parts of the Brain muscle coordination Cortex: thinking, learning, memory, speech movement, senses breathing, heart rate, blood pressure sends sensory input to cerebrum homeostasis

18. Spinal Cord and Reflex Arcs Involve the Somatic Nervous System

19. Autonomic Nervous System speeds heart slows heart dilates air passages constricts bronchioles decreases stomach and intestinal activity increases stomach and intestinal activity dilates pupils constricts pupils

20. Applying Your Knowledge Which one A.Is responsible for increasing breathing rate when you start running? B.Includes the spinal cord? C.Controls skeletal muscle movement? 1.Central Nervous System 2.Somatic Nervous System 3.Autonomic Nervous System

21. Nervous System Disorders Alzheimer Disease: gradual loss of neural function due to tangles and plaques associated with axonsAlzheimer Disease: gradual loss of neural function due to tangles and plaques associated with axons Parkinson Disease: deficiency of dopamine causes tremors, rigidity, shuffling gaitParkinson Disease: deficiency of dopamine causes tremors, rigidity, shuffling gait Huntington Disease: uncoordinated movements and degenerative neurological symptoms beginning at middle age, due to autosomal dominant inheritanceHuntington Disease: uncoordinated movements and degenerative neurological symptoms beginning at middle age, due to autosomal dominant inheritance