Survey of Anatomy and Physiology Chap 9 Part Two

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Survey of Anatomy and Physiology Chap 9 Part Two

  1. 1. 9 The Nervous System: The Body's Control Center
  2. 2. Part Two 
  3. 3. Neuroglia-Glial Cells   Specialized cells in Central Nervous System called neuroglia, or glial cells, perform specialized functions. Four types:
  4. 4. Nerve TissueGlial Cells  Specialized cells in nervous system called neuroglia, or glial cells, perform specialized functions Metabolic and structural support
  5. 5. Nerve TissueGlial Cells  Specialized cells in nervous system called neuroglia, or glial cells, perform specialized functions Attack Microbes and remove debris
  6. 6. Nerve TissueGlial Cells  Specialized cells in nervous system called neuroglia, or glial cells, perform specialized functions Cover and line cavities of nervous system
  7. 7. Nerve TissueGlial Cells  Specialized cells in nervous system called neuroglia, or glial cells, perform specialized functions Makes lipid insulation called myelin
  8. 8. Neuroglia-Glial Cells   Specialized cells in Peripheral Nervous System called neuroglia, or glial cells, perform specialized functions. Two types:
  9. 9. Nerve TissueGlial Cells  Specialized cells in nervous system called neuroglia, or glial cells, perform specialized functions Makes myelin for PNS
  10. 10. Nerve TissueGlial Cells  Specialized cells in nervous system called neuroglia, or glial cells, perform specialized functions Support cells
  11. 11. Figure 9-2 Glial cells and their functions. 
  12. 12. Nerve Tissue-The Neuron   Each part of neuron has specific function  Body/Soma: cell Body/Soma metabolism  Dendrites: receive Dendrites information from the environment  Axon: generates and sends Axon signals to other cells
  13. 13. Figure 9-3 A neuron connecting to a skeletal muscle.  Each part of neuron has specific function: Axon terminal: where terminal signal leaves cell Synapse: where axon Synapse terminal and receiving cell combine
  14. 14. Neurons  Neurons are classified by how they look (structure) Neurons are classified by how they look (structure) or what they do (function) or what they do (function)
  15. 15. How Neurons Work   Neurons can use their ability to generate electricity to send, receive, and interpret signals
  16. 16. How Neurons Work   Neurons are called excitable cells; this simply means that if cell is stimulated it can carry small electrical charge. charge  Each time charged particles flow across a cell membrane, there is tiny charge generated
  17. 17. How Neurons Work   All three muscle types are excitable cells, as are many gland cells  Cells are like miniature batteries, able to generate batteries tiny currents simply by changing permeability of their membranes
  18. 18. The Action Potential   Series of permeability changes within the cell and the resultant changes in the charge across the cell membrane
  19. 19. The Action Potential  Changes in the Cell • • • • • Polarized Depolarized Repolarization Hyperpolarization Refractory
  20. 20. Resting Cell-Polarized   A cell that is not stimulated or excited is called a resting cell; it cell is said to be polarized  It has a difference in charge across its membrane, being more negative inside than on the outside cell
  21. 21. Stimulated CellDepolarized   When cell is stimulated, sodium gates in the cell membrane spring open, allowing sodium open to travel across membrane  Sodium bits are positively charged, so charged cell becomes more positive as they enter
  22. 22. Repolarization   Sodium gates close after a few minutes and potassium gates open; potassium leaves cell, open taking its positive charge with it
  23. 23. Hyperpolarization   If cell becomes more negative than resting it is called hyperpolarized  Action potential (AP) is cell moving through depolarization, repolarization, and repolarization hyperpolarization
  24. 24. Refractory Period   Cell cannot accept another stimulus until it returns to its resting state, and this time period when it cannot accept another stimulus is called refractory period
  25. 25. Figure 9-4 The action potentialpage 209.
  26. 26. Myelin Increases Conduction   Speed of impulse conduction is determined by amount of myelin and diameter of axon
  27. 27. Myelin Increases Conduction   Myelin is lipid insulation or sheath formed by oligodendrocytes in CNS and…  Schwann cells in cel PNS
  28. 28. Myelinated axon vs. Unmyelinated  .5 meters/second 100 meters/second Myelin is essential for speedy flow of Action potential down the axon Un-myelinated axon has to depolarize each and every millimeter of axon
  29. 29. Figure 9-5 Wider axons conduct faster  Diameter of axon also affects speed of action potential flow; wider the diameter of axon, faster the flow of ions
  30. 30. Figure 9-5 Impulse conduction via myelinated axon.  Nerve impulse jumps from the bare areas between myelin sheath called the Nodes of Ranvier which is FASTER
  31. 31. How Synapses Work   Watch Video “How Synapses Work” https://www.youtube.com/wa
  32. 32. How Synapses Work   When AP* arrives at axon terminal, terminal depolarizes and calcium gates open; calcium ions flows into cell; when calcium flows in, it triggers change in terminal *Action potential
  33. 33. How Synapses Work   There are tiny sacs in terminal called vesicles that release their contents from cell when calcium flows in Vesicles Vesicles
  34. 34. How Synapses Work   Vesicles are filled with molecules called neurotransmitters that send signal from neuron across synapse to next cell in line
  35. 35. How Synapses Work   Once released the neurotransmitter binds to receptors on postsynaptic membrane. Each neurotransmitter has a specific receptor
  36. 36. How Synapses Work   The specific Sodium channels neurotransmitter determines whether the impulse continues which is called EXCITATION allowing Sodium (Na+) channels to open and membrane is depolarized and
  37. 37. How Synapses Work   The specific Potassium channels neurotransmitter determines whether the impulse is blocked which is called INHIBITION allowing Potassium (K+) channels to open and the impulse STOPS
  38. 38. How Synapses Work   The receptor then Enzymes releases the neurotransmitter after which it is reabsorbed by the synaptic knobs and recycled or destroyed by enzymes.
  39. 39. Chemical Synapse   Use of neurotransmitters is called chemical synapse because chemicals carry information from one cell to another
  40. 40. Chemical Synapse  Figure 9-6 . Step 1: The impulse travels down the axon. Step 2: Vesicles are stimulated to release neurotransmitter (exocytosis). Step 3: The neurotransmitter travels across the synapse and binds with the receptor site of post synaptic cell. Step 4: The impulse continues down the dendrite.
  41. 41. Neurotransmitters  Acetylcholine Generally excitatory, but sometimes excitatory Norepinephrine May be excitatory or inhibitory depending on receptor Epinephrine May be excitatory or inhibitory depending on receptors Serotonin Generally inhibitory Endorphins Generally inhibitory
  42. 42. Clean up at the Synapse  After neurotransmitters create a nerve impulse at the synapse, enzymes “reuptake” or clean up the chemicals and use them again
  43. 43. Antidepressants   Selective serotonin reuptake inhibitors (SSRIs) are medications that prevent cleanup of neurotransmitter serotonin from synapses, thus increasing effects of serotonin on receiving cell
  44. 44. Electrical vs Chemical Synapse  Gap junction •• Cells do not need Cells do not need chemicals to chemicals to transmit transmit information from information from one cell to another one cell to another •• Can transfer info Can transfer info because of special because of special connection called connection called GAP JUNCTION GAP JUNCTION
  45. 45. Electrical Synapse  Electrical Electrical synapses with synapses with gap junction gap junction are found in the are found in the intercalated intercalated discs of cardiac discs of cardiac muscle cells muscle cells
  46. 46. Electrical vs Chemical Synapse 
  47. 47. In Class WORKSHEET  Complete the worksheet using ONLY YOUR NOTES-NO TEXTBOOK or LAP TOPS, TABLETS You will not need to complete the Chapter 9 worksheets for credit but use simply for STUDY GUIDE for your test
  48. 48. EXAM-Chapters 6 & 7  Your exam is Tuesday Oct 29 at 9:30 a.m. It will have questions from: •Power Point Presentations on Chapter 6 & 7 •Essay on functions of skeletal system •Explain osteoporosis and cells of bone formation •Step by step of Muscle contraction •Diagram on specific joint •Extra credit: MUSCLE TONE page 149 in your textbook

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