1. Warm-Up 5/8 1.The sympathetic nervous system has what effect on the body? 2.What portion of the nervous system is responsible for voluntary movement? 3.Support or contradict this statement: If two individuals receive exactly the same sensory information, their “integration” of that information will always be identical.

4. NEURON STRUCTURE & NEURAL CELL TYPES

5. NERVOUS TISSUE CELLS

6. 2 Neural cell types: Neurons & Neuroglial cells A.K.A: -Neuroglia -Glia -Glial cells AMAZING variety in shapes and sizes! NERVOUS TISSUE CELLS

7. Neurons transmit nerve impulses known as “Action Potentials” (AP) Neuroglia carry out a variety of functions to aid and protect the nervous system. Neural Cell Functions

8. STRUCTURE OF NEURON

9. Neurons: Nerve cells. Unique structure – cell body with many extensions or processes (nerve “fibers”) which conduct impulses. 1. Dendrites – shorter, more numerous. These, along with the cell body, form the receptive surfaces of neurons. 2. Axons – single, long “fiber” which conducts impulse away from the cell body. Sometimes it is “branched” (collaterals). End has many fine branches called AXON TERMINALS 3. Soma – Cell body

10. On peripheral axons, a fatty MYELIN SHEATH surrounds and insulates the axon. Functions to speeds up signal transmission.

12. MEMBRANE POTENTIAL/ NERVE IMPULSE

13. Here is a Neuron. Charged particles and ions exist both inside and outside of the cell. However, distribution of these charged particles is not identical inside and outside.

14. OUTSIDE CELL (Extracellular) INSIDE CELL (Intracellular) Lots of Sodium (Na + ) ions Few Potassium (K + ) Lots of Potassium (K + ) Few Sodium (Na + ) ions

15. Extracellular Intracellular (Na + ) (K + ) (Na + ) So they spend energy (ATP) to keep Sodium out and Potassium in! Neurons NEED this distribution of ions to function! Ions will SLOWLY leak across membrane via diffusion.

16. Burns ATP for energy to do work. Pushes sodium ions out of the cell and potassium ions into the cell. EXTRACELLULAR INTRACELLULAR Na + /K + pump Protein in cell membrane that moves ions!

17. Cell at REST. (Unstimulated) + ++++++++ ------------------ Outside has more positively charged particles. Inside the cell there is an excess of negative charges caused in part by the negative charge on most proteins

18. (Na + ) (K + ) (Na + ) This difference in concentration and charge causes a force on the particles to move across the membrane! + ++++++++ ------------------ Electro-Chemical Gradient! This “force” across the membrane creates something known as the “membrane potential”

19. Lots of (Na + ) Few (Na + ) FORCE + +++++ ------------ Membrane Potential RESTING MEMBRANE POTENTIAL (RMP)- difference in electrical charge across the membrane at “rest” Measured in milli-volts (mV) RMP of cell = -70mV -70mV

20. Stimulation + +++ Some input opens a channel in the membrane! (touch, temperature, neurotransmitter etc.) Most neurotransmitter receptors are simply doors for ions that are unlocked by a their target neurotransmitter. + +++ -70mV

21. + +++ Channel opens and lets some sodium sneak into the cell! This causes slight depolarization of membrane! + +++ Stimulation -70mV + ++ -63mV

22. + +++ If enough positive ions can get into the cell to get the membrane potential to -55mV (threshold) it will stimulate an Action potential! + +++ Stimulation -70mV + ++ -63mV-55mV ACTION POTENTIAL! THRESHOLD!

23. When an action potential occurs… 1.Sodium ions rush into the neuron causing a positive charge inside the axon

24. When an action potential occurs… 2. This influx of Na+ (sodium) causes a similar change in the next region of the axon

25. When an action potential occurs… 2. This influx of Na+ (sodium) causes a similar change in the next region of the axon

26. When an action potential occurs… 3. The electrical nerve impulse (positive charge) moves like a wave down the axon

27. 4.K+ channels open to repolarize the membrane 5.The Na+/K+ pump restores the original balance of ions to resting levels

28. END. VIDEO! Muahahaha….