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Unit #7 Nervous System: Neurons

Unit #7 Nervous System: Neurons. Tortora Pages 225. Introduction. Two systems of communication Nervous system Rapid response Uses action potentials Endocrine system Slower response Uses hormones. Tortora Pages 225. Did You Know?.

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Unit #7 Nervous System: Neurons

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  1. Unit #7 Nervous System: Neurons

  2. Tortora Pages 225 Introduction • Two systems of communication • Nervous system • Rapid response • Uses action potentials • Endocrine system • Slower response • Uses hormones

  3. Tortora Pages 225 Did You Know? • Many types of mental illnesses are related to imbalances in chemicals that transmit messages between neurons

  4. Tortora Pages 205 - 207 Introduction • Nervous system • CNS • PNS

  5. Tortora Pages 205 - 207 Introduction • Endocrine system • Ductless glands • Pituatary (master gland)

  6. Tortora Pages 205 - 207 Functions of Nervous System • Sensory

  7. Tortora Pages 205 - 207 Functions of Nervous System • Integrative

  8. Tortora Pages 205 - 207 Functions of Nervous System • Motor

  9. Tortora Pages 205 - 207 Organization of Nervous System • Central Nervous System • Brain • Spinal cord

  10. Tortora Pages 205 - 207 Organization of Nervous System • Peripheral Nervous System • Cranial nerves • Spinal nerves

  11. Tortora Pages 205 - 207 Organization of Nervous System • Sensory, Motor, and Connecting Neurons • Sensory are referred to as afferent. • Motor are referred to as efferent. • Connecting are referred to as association

  12. Tortora Pages 205 - 207 Organization of Nervous System • Somatic Vs Autonomic • Somatic is voluntary • Sensory nerves and motor nerves. • Autonomic is involuntary • Mostly motor nerves leading to smooth muscle, cardiac muscle, and glands.

  13. Tortora Pages 205 - 207 Organization of Nervous System • Symapathetic Vs Parasymnpathetic ANS • Oppose each others actions. • Regulates homeostasis.

  14. Histology TortoraPages 207 - 210 Histology • Two types of cells • Neurons conduct impulses. • Neuroglial cells support and protect neurons. Neurons found in the spinal cord.

  15. Histology TortoraPages 207 - 210 • Neuroglia • Smaller than neurons. • Outnumber neurons 5 to 50 times. • Six different types. Neurons found in the spinal cord.

  16. Histology TortoraPages 207 - 210 • Neurons. • 3 distinct areas • Cell body. • Dendrites. • Axons. Neurons found in the spinal cord.

  17. Histology TortoraPages 207 - 210 • Cell body of neuron. • Nucleus • Typical cell organelles. • No mitotic spindle. Neurons found in the spinal cord.

  18. Histology TortoraPages 207 - 210 • Neurons are in three forms. • Multipolar • Bipolar • Unipolar

  19. Histology TortoraPages 207 - 210 • Neurons are in three sizes. • Type A • Largest diameters • 130 M/sec • Type B • Middle sized • 10 M/sec • Type C • Smallest • .5 M/sec • unmyelinated Neurons and their many branches

  20. Histology TortoraPages 207 - 210 • Dendrites • Usually short and thick. • Usually highly branched. • Receives impulses. • Conducts impulses towards cell body. Dendrites surrounded by neuroglial cells.

  21. Histology TortoraPages 207 - 210 • Axons • Neurons have a single axon. • Usually long and very thin. • Can be branched (collaterals) • Terminates in many terminals. • Terminals contain vesicles. • Vesicles contain neurotransmitters. Axon surrounded by neuroglial cells

  22. Histology TortoraPages 207 - 210 • Myelin sheath • Speeds impulse along axon. • Insulates axon . • Composed of neuroglial cells. (PNS) • Schwann cells produce myelin (lipoprotein) • Nodes of Ranvier create gaps in myelin sheath. Myelin sheath structure

  23. TortoraPages 207 - 210 Histology • Grouping of Neural tissue • White matter is myelinated. • Gray matter is unmyelinated.

  24. Tortora Pages 210-213 Nerve Impulses • Nerve impulse • An imlpulse is a change in the electrical charge (potential) on the membrane of the neuron. • Due to ions moving into and out of the neuron.

  25. Tortora Pages 210-213 Nerve Impulses • Ions move through very selective membrane channels. • Channels are transmembrane proteins. • Channels open or close in response to certain changes. • Voltage gated channels

  26. Tortora Pages 210-213 Nerve Impulses • Membrane Potentials. • Resting potential - no impuse. • Positive outside • Negative inside. • Action potential. • Positive inside. • Negative outside. • Potentials are due to ions. • Na + • K+ • Large negative ions (proteins)

  27. Tortora Pages 210-213 Nerve Impulses • Resting potential • No impulse. • Positive outside neurolemma • Negative inside. • 30x more K+ inside. • 15x ore Na+ outside. • Large negative ioins trapped inside. • Sodium - Potassium pump creates these conditions. • Membrane is “polarized”. Creating An Impulse Along An Axon

  28. Caffeine & the Nervous System

  29. TortoraPages 207 - 210 Histology • Nerves are groups of neurons. • Mixed contain dendrites and axons. • Motor contain axons only. (Efferent) • Sensory contain dendrites only. (Afferent)

  30. Tuesday 1/20/04Pages 213-214 Conduction Across Synapses • Impulses are sent to: • Glands • Muscles • Other neurons. • Impulse must bridge synapse

  31. Tuesday 1/20/04Pages 213-214 Conduction Across Synapses • Synapses have ability to transmit impulse or inhibit impulse transmission.

  32. Tuesday 1/20/04Pages 213-214 Conduction Across Synapses • Most brain disorders involve disruption of synaptic communication.

  33. Tuesday 1/20/04Pages 213-214 Conduction Across Synapses • Presynaptic neuron • Synaptic vesicles • Neurotransmitter • Role of calcium ions • Synaptic cleft • Postsynaptic neuron. • receptors Voltage gated channels Na+/K+ Pump Conduction Across A Synapse

  34. Tuesday 1/20/04Pages 213-214 Saltatory Conduction

  35. Tuesday 1/20/04Pages 213-214 REGENERATION OF NERVOUS TISSUE • Neurons have limited power of regeneration. • Ability to reproduce lost at 6 months of age. • A destroyed neuron is lost. • PNS neurons can repair. • CNS neurons cannot repair.

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