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Chapter 9

Chapter 9. Histology of the Nervous Tissue. nervous system overview. Nervous system Monitors and processes sensory information from the environment and from within the body Principal cell populations Neuron Neuroglia. The Anatomy of a Neuron. Neuron structure.

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Chapter 9

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  1. Chapter 9 Histology of the Nervous Tissue

  2. nervous system overview • Nervous system • Monitors and processes sensory information from the environment and from within the body • Principal cell populations • Neuron • Neuroglia

  3. The Anatomy of a Neuron

  4. Neuron structure • Nissl bodies – clusters of RER and ribosomes • Dendrites • Receptive region • Axon or nerve fiber • Nerve impulse generator and transmitter • Axon hillock • Axon terminal or synaptic knobs • Collaterals with telodendria

  5. Neuron structure • Synaptic terminals • Presynaptic membrane • Synaptic vesicles • neurotransmitter • Synaptic cleft • Postsynaptic membrane

  6. Neurons • They make up the gray matter of the nervous system • Clusters of cell bodies, dendrites, unmyelinated axons and neuroglias are called: • Nuclei if they are located in the CNS • Ganglia if they are located in the PNS

  7. Axons or nerve fibers • Covered by myelin • Fatty material secreted by Schwann cells in the PNS • Fatty material secreted by oligodendrocytes in the CNS • Myelin insulates the axons

  8. Axons or nerve fibers • In the PNS • The wrapping of the Schwann cell around the axon is called myelin sheath • Neurilemma • It is the peripheral layer of the Schwann cell • It contains the nucleus and most of the organelles • Nodes of Ranvier • Gaps between Schwann cells

  9. Neuron classification • Anatomical or structural • Unipolar • Bipolar • Multipolar

  10. A Structural Classification of Neurons

  11. Neuron classification • Functional • Sensory neurons or afferent neurons • deliver information from the body to the CNS • Typically unipolar or bipolar • Body found in a ganglia (PNS)

  12. Neuron classification • Motorneurons or efferent neurons • Carry impulse from the CNS to the body • Typically multipolar • Body found in the CNS • Association(interneuron) neuron • Found between and sensory and a motor neuron

  13. Structure of a nerve • Definition • Bundle of fibers wrapped in myelin and connective tissue • Located in the PNS • Classification • Sensory or afferent– going to the CNS • Motor or efferent- going to the body • Mixed – carry sensory and motor fibers

  14. Structure of a nerve • The connective tissue that surrounds the fiber is called • Endoneurium-covers each nerve fiber • Perineurium – covers a bundle of nerve fibers • The whole bundle is called fascicle • Epineurium – covers the whole nerve

  15. Chapter 10Neurophysiology

  16. Neurophysiology • Nerve impulse • Excitability • Conductivity • Resting membrane potential • Polarized • Threshold stimulus

  17. Neurophysiology • Depolarization • Action potential • Repolarization • Refractory period • Absolute • relative

  18. Chapter 12 Electroencephalography

  19. Electroencephalography - EEG • Measures brain activity • Alpha waves = awake with eyes closed. Resting. • Alpha block • Beta waves = awake with eyes opened. Alert. • Delta waves = normal during sleep • Theta waves = normal children, abnormal in adults

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