1. ELAINE N. MARIEB EIGHTH EDITION 7 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Lecture Slide Presentation by Jerry L. Cook, Sam Houston University ESSENTIALS OF HUMAN ANATOMY & PHYSIOLOGY PART A The Nervous System

2. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functions of the Nervous System  Sensory input – gathering information  Monitor changes (stimuli) occurring inside and outside the body  Integration  To process and interpret sensory input and decide if action is needed  Motor output  Activate muscle or gland in response to integrated stimuli

3. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Nervous System Microanatomy  Nervous tissue made up of different kinds of cells:  Neurons - “Nerve cell” or “Nerve fiber,” conduct nerve impulses  Neuroglia or Supporting cells - Assist neurons

4. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Nervous System Microanatomy  A nerve = a long bundle of parallel neurons  Brain tissue = complex network of neurons

5. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Nervous Tissue: Neurons  Neuron (draw this picture, we’ll label it as we go)

6. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Neuron Anatomy  Cell body  Contains nucleus & most major cell organelles Figure 7.4a–b

7. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Neuron Anatomy  Extensions outside the cell body  Dendrites – receive incoming impulses, conduct impulses toward the cell body Figure 7.4a

8. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Neuron Anatomy  Extensions outside the cell body  Axon – conducts impulses away from the cell body, communicate them to neighboring dendrites Figure 7.4a

9. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Neuron Anatomy  Myelin sheath  Electrically insulating lipid- protein layer around axon  Prevents electrical current from leaving axon  Increases impulse speed  Provides track along which axon can regrow if severed Figure 7.4a

10. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Axons and Nerve Impulses  Axon terminal = end of axon, has vesicles (“bubble packets”) of neurotransmitter  Synapse = Junction between neurons  Synaptic cleft = Gap between axon terminal and dendrite

11. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

12. Nerve Impulse  Neurons “communicate” by transmitting an electrical impulse called an action potential  Impulse passed neuron-to-neuron along a chain either to (sensory) or from (motor command) the brain  Hand-slapping game - only a rough demo!

13. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Action Potential  1. A stimulus disturbs sodium ion gates in the cell membrane, allowing sodium (Na + ) to flow in (depolarization)  2. Neighboring sodium gates are voltage- sensitive, and open up due to the sudden change in charge. Na+ is now flowing in at two adjacent locations. Figure 7.9a–c

14. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Action Potential  3. Step 2 repeats. This moving depolarization = an action potential.  4. Voltage-triggered potassium gates open in the wake of the action potential, allowing K+ out which restores original charges (repolarization)  5. Sodium-potassium pumps in membrane activate in wake of movement of Na+ and K+, conduct active transport to move both ions back to original conditions

15. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Action Potential  http://highered.mcgraw- hill.com/sites/0072495855/student_view0/cha pter14/animation__the_nerve_impulse.html http://highered.mcgraw- hill.com/sites/0072495855/student_view0/cha pter14/animation__the_nerve_impulse.html

16. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Synaptic Transmission  Because an action potential is a change in Na+ and K+ along a membrane, it can’t jump from cell to cell  Instead:  6. When action potential reaches axon terminal, neurotransmitter vesicles are stimulated to “pop” and release neurotransmitter into synaptic cleft

17. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Synaptic Transmission  7. The dendrite of the next neuron has receptors that are stimulated by neurotransmitter attachment  8. Stimulated receptors trigger the opening of an adjacent sodium gate: A new action potential is started in the dendrite

18. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Synaptic Transmission  http://highered.mcgraw- hill.com/sites/0072495855/student_view0/cha pter14/animation__transmission_across_a_sy napse.html http://highered.mcgraw- hill.com/sites/0072495855/student_view0/cha pter14/animation__transmission_across_a_sy napse.html

19. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Neuroglia  Essential neuroglia (support cells)

20. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 7.3a Neuroglia  Astrocytes  Brace neurons  Form barrier between capillaries and neurons

21. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Neuroglia  Microglia  Dispose of debris  Ependymal cells  Line cavities of the brain and spinal cord  Circulate cerebrospinal fluid Figure 7.3b–c

22. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Neuroglia  Oligodendrocytes  Produce myelin sheath around nerve fibers in brain, spinal cord Figure 7.3d

23. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 7.3e Neuroglia  Schwann cells  Form myelin sheath in peripheral (body) nerves

24. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

25. Organization of the Nervous System Figure 7.2

26. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Organization of the Nervous System  I. Central nervous system (CNS) (brain & spinal cord)  II. Peripheral nervous system (PNS) (nerves outside brain & spinal cord)

27. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 7.1 Functional Classification of the Peripheral Nervous System  II. PNS  A. Sensory (afferent) division - Nerve fibers that carry information to the central nervous system

28. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 7.1 Functional Classification of the Peripheral Nervous System  II. PNS  B. Motor (efferent) division - Nerve fibers that carry impulses away from the central nervous system

29. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 7.1 Functional Classification of the Peripheral Nervous System  B. Motor (efferent) division  1. Somatic nervous system = voluntary  2. Autonomic nervous system = involuntary

30. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functional Classification of Neurons  Interneurons (association neurons)  Found in neural pathways in the central nervous system  Connect sensory and motor neurons

31. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Neuron Classification Figure 7.6

32. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Organization of the Nervous System Figure 7.2

33. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Spinal Cord  Extends from the medulla oblongata down through spinal column  Spinal nerves exit at each vertebra, connect to specific body region Figure 7.18

34. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Spinal Cord Anatomy  Central canal filled with cerebrospinal fluid  Surrounded by white and gray matter (nerve tissue) Figure 7.19

35. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Spinal Cord Anatomy  Covered by meninges - protective membranes Figure 7.19