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Neuroscience: Exploring the Brain, 3e

Neuroscience: Exploring the Brain, 3e. Chapter 2: Neurons and Glia. Introduction. “Neurophilosophy” Brain is the origin of mental abilities Glia and Neurons Glia: Insulates, supports, and nourishes neurons Neurons Process information Sense environmental changes

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Neuroscience: Exploring the Brain, 3e

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  1. Neuroscience: Exploring the Brain, 3e Chapter 2: Neurons and Glia

  2. Introduction • “Neurophilosophy” • Brain is the origin of mental abilities • Glia and Neurons • Glia: Insulates, supports, and nourishes neurons • Neurons • Process information • Sense environmental changes • Communicate changes to other neurons • Command body response

  3. The Neuron Doctrine • Histology • Study of tissue structure • The Nissl Stain • Facilitates the study of cytoarchitecture in the CNS

  4. The Neuron Doctrine • Golgi-stain (Developed by Camillo Golgi) shows two parts of neurons: • Soma and perikaryon • Neurites: Axons and dendrites

  5. The Neuron Doctrine • Cajal’s Contribution • Neural circuitry • Neurons communicate by contact, not continuity • Neuron doctrine • Neurons adhere to cell theory • Based in Golgi stain

  6. The Prototypical Neuron • The Soma • Cytosol: Watery fluid inside the cell • Organelles: Membrane-enclosed structures within the soma • Cytoplasm: Contents within a cell membrane (e.g., organelles, excluding the nucleus)

  7. The Prototypical Neuron • The Axon • Axon hillock (beginning) • Axon proper (middle) • Axon terminal (end) • Differences between axon and soma • ER does not extend into axon • Protein composition: Unique

  8. The Prototypical Neuron • The Axon • The Axon Terminal • Differences between the cytoplasm of axon terminal and axon • No microtubules in terminal • Presence of synaptic vesicles • Abundance of membrane proteins • Large number of mitochondria

  9. The Prototypical Neuron • The Axon • Synapse • Synaptic transmission • Electrical-to-chemical-to-electrical transformation • Synaptic transmission dysfunction • Mental disorders

  10. The Prototypical Neuron • The Axon • Axoplasmic transport • Anterograde (soma to terminal) vs. Retrograde (terminal to soma) transport

  11. The Prototypical Neuron • Dendrites • “Antennae” of neurons • Dendritic tree • Synapse - receptors • Dendritic spines • Postsynaptic (receives signals from axon terminal)

  12. Classifying Neurons • Classification Based on the Number of Neurites • Single neurite • Unipolar • Two or more neurites • Bipolar- two • Multipolar- more than two

  13. Classifying Neurons • Classification Based on Dendritic and Somatic Morphologies • Stellate cells (star-shaped) and pyramidal cells (pyramid-shaped) • Spiny or aspinous

  14. Classifying Neurons • Further Classification • By connections within the CNS • Primary sensory neurons, motor neurons, interneurons • Based on axonal length • Golgi Type I (projection neurons) • Golgi Type II (local interneurons) • Based on neurotransmitter type • e.g., – Cholinergic = Acetycholine at synapses

  15. Glia • Function of Glia • Supports neuronal functions • Astrocytes • Most numerous glia in the brain • Fill spaces between neurons • Influence neurite growth • Regulate chemical content of extracellular space

  16. Glia • Myelinating Glia • Oligodendroglia (in CNS) • Schwann cells (in PNS) • Insulate axons

  17. Glia • Myelinating Glia (Cont’d) • Oligodendroglial cells • Node of Ranvier • Region where the axonal membrane is exposed

  18. Glia • Other Non-Neuronal Cells • Microglia as phagocytes (immune)

  19. Structure Correlates with Function NEURONS Soma Axons Dendrites Synapse Structural characteristics of a neuron tell us about its function e.g., Dense Nissl stain = protein; suggestsspecialization Elaborate structure of dendritic tree = receiver

  20. End of Presentation

  21. The Prototypical Neuron • The Soma • Major site for protein synthesis • Rough endoplasmic reticulum

  22. The Prototypical Neuron • The Nucleus • Gene expression • Transcription • RNA processing

  23. The Prototypical Neuron • The Soma • Protein synthesis also on free ribosomes; polyribosomes

  24. The Prototypical Neuron • The Soma • Smooth ER and Golgi Apparatus • Sites for preparing/sorting proteins for delivery to different cell regions (trafficking) and regulating substances

  25. The Prototypical Neuron • The Soma • Mitochondrion • Site of cellular respiration (inhale and exhale) • Krebs cycle • ATP- cell’s energy source

  26. The Prototypical Neuron • The Neuronal Membrane • Barrier that encloses cytoplasm • ~5 nm thick • Protein concentration in membrane varies • Structure of discrete membrane regions influences neuronal function

  27. The Prototypical Neuron • The Cytoskeleton • Not static • Internal scaffolding of neuronal membrane • Three “bones” • Microtubules • Microfilaments • Neurofilaments

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