1. Nervous System

2. Divisions of the Nervous System Central Nervous System (CNS) Made up of the Brain and Spinal Cord Peripheral Nervous System (PNS) All neural tissue outside of CNS

3. Functional Division of the Nervous System CNS Integrates and coordinates information Involved in higher functioning PNS Transmits information to and from the CNS Sends information to the CNS (Sensory) Gets information from the CNS (Motor)

4. Types of Neural Tissue Neuron Responsible for information transfer and processing Neuroglial Cells Provide the framework for neurons Phagocytic Different types for each division CNS Astrocytes Oligodendrocytes Microglial PNS Schwann Cell

5. Neuron Structure

6. Neuron Structure Part 1 Cell Body Nucleus Axon: Carries the nerve impulse away from the cell body Dendrite: Carries the nerve impulse towards the cell body Myelin: Fatty substance that encases some of the axon Allows nerve impulse to travel faster by jumping from node-to- node Nodes of Ranvier: Gaps between myelin Schwann Cells: Produce the myelin

7. Neuron Structure Part 2 White Matter: areas of neural tissue with myelin LOTS of axons Gray Matter: areas of neural tissue without myelin LOTS of cell bodies

8. Question What do you think are some of the consequences if Schwann Cells over time start to deteriorating?

9. Synapse Where the communication between cells takes place How? Through the release of neurotransmitters Very similar to NMJ, but reuptake happens

10. Steps at Synapse 1.Nerve impulse travels down presynaptic neuron 2.Presynaptic neuron releases NTs from synaptic vesicles into synaptic cleft 3.NTs land on receptors of postsynaptic neuron 4.Postsynaptic neuron responds 5.NTs return to presynaptic neuron in a process called ‘reuptake’

11. Action Potential (Nerve Impulse) Action Potential The electrochemical changes that move along a cell to transmit information In neurons, action potentials involve sodium (Na) and potassium (K) and their movement across the cell membrane Propagation of an action potential down a nerve fiber is called a nerve impulse

12. Action Potential Graph X-Axis: Time Y-Axis: Membrane Potential (mV) Way to measure electrical charge of the cell Steps we will write out DO NOT match the numbers on your graph

13. 1. Resting Potential Resting neuron’s cell membrane is polarized/charged because there is an uneven distribution of ions on both sides of the cell membrane Inside cell (-): K, PO, SO Outside cell (+): Na Membrane Potential: -70 mV

14. 2. Depolarization STIMULUS Na channels open and Na moves into cell Membrane depolarizes from -70 mV to -55 mV -55 mV is called THRESHOLD (minimum charge needed from impulse to move on) Amount of change in potential (charge) is directly proportional to intensity of stimulus Occurs at portion of cell membrane being stimulated and moves to next part of cell membrane once threshold is reached

15. 3. Action Potential At threshold, ALL Na channels suddenly open and Na rushes into cell Membrane depolarizes from -55 mV to +30 mV

16. 4. Repolarization At +30 mV, Na channels close, K channels open and K rushes out Causes repolarization back to resting potential (-70 mV) At -70 mV, sodium-potassium pump exchanges Na and K to resets 3 Na for 2 K

17. Look at Graph…

18. Poll Everywhere Question https://www.polleverywhere.com/free_text_polls/hkG1O5zmTmSVxZ h https://www.polleverywhere.com/free_text_polls/hkG1O5zmTmSVxZ h

19. Meninges Connective tissue that covers the brain and spinal cord Made of 3 basic layers Dura Mater Arachnoid Mater Pia Mater

20. Meningeal Layers Dura Mater “Tough Mother” Outermost Layer Made of dense connective tissue, super thick! Supports and protects

21. Meningeal Layers Arachnoid Mater “Spider Mother” Middle Layer Web-like Holds Fluid

22. Meningeal Layers Pia Mater “Delicate Mother” Innermost Layer Made of collagen and elastin, very thin! Contains blood vessels that supply the brain

23. Cerebrospinal Fluid (CSF) Found within the Arachnoid Layer Filtered by blood brain barrier Very protective: chemically and physically Clear and colorless

24. Spinal Cord Structure Adult length: 16-18 inches Extends from foramen magnum to L2 Portion of nerves after L2 is often referred to as a “Horsetail” (Cauda equina) Functions Conducts nerve impulses Center for spinal reflexes

25. Spinal Cord What is the significance of the gray matter? Unmyelinated More neuron cell bodies in gray matter than white matter, so more “work” can be done…