Lecture 16 sldies

• Integrating and coordinating - Maintaining homeostasis.
• Integrating and coordinating


  1. Sensory experience

  2. Integration (often happens with your knowing it)

  3. Coordination

  4. Response
• The nervous system is composed of the brain, spinal cord, and peripheral nerves & ganglia.
• Cells of the nervous system

  • Neurons
  • Glia
• Neurons


  • Cells specialised for transmission of information
  • Four (4) morphological types
• Glia


  • Support for neurons
  • Five basic types
  • Each type has specific function
• Neuron - Cell body

  • Contains nucleus & organelles
  • Sums input
• Neuron - Axon


  • Carries electrical impulses
  • May or may not be myelinated
• Neuron - Axon terminal(s)


  • End (terminus) of the axon
  • Neurotransmitter release
• Neuron - Dendrites


  • Receive input
  • Send info to cell body
• Organisation of the nervous system - Cell bodies and axons

  • Nucleus (pl. = Nuclei)
  • Tract
  • Grey matter
  • White matter
• Organisation of the nervous system - Cell bodies and axons (PNS)

  • Ganglion (pl = ganglia)
  • Nerve
• Neuron - Functional components

  • Input zone (Dendrites and cell body)
  • Summation zone (Axon hillock)
  • Conduction zone (Axon)
  • Output zone (Axon terminals)
• Axon hillock: Anatomical location where inputs are summated before action potential.
• Atheletes' bodies are specialised for specific tasks, so they look different.
• Lock


  Anatomical location where inputs are summated before action potential
• Cells of the nervous system are specialised for specific tasks, so they look different
• Morphological types of neurons

  • Multipolar
  • Bipolar
  • Unipolar
  • Anaxonic (axonless)
• Multipolar neurons


  • Multiple processes emanate from the cell body
• Bipolar neurons


  • Two processes emanate from the cell body
• Unipolar neurons


  • One process emanates from the cell body, then branches into dendrite and axon
• Anaxonic (axonless) neurons


  • No distinct axon, all processes look alike
• Central Nervous System Glia

  • Astrocytes
  • Ependymal cells
  • Oligodendrocytes
  • Microglia
• Astrocytes


  • Supply nutrients to neurons
  • Ensheath blood capillaries
  • Injury response
• Ependymal cells


  • Line fluid-filled spaces of brain and spinal cord
  • Have cilia (hair-like processes) to circulate CSF
• Oligodendrocytes


  • Support nerve fibres
  • Ensheath them with myelin
• Microglia


  • Immune cells of the CNS
  • Engulf microorganisms and debris
• Peripheral Nervous System Glia


  • Schwann cells
• Schwann cells


  • Support peripheral nerve fibres
  • Ensheath them with myelin
  • Similar to oligodendrocytes (CNS)
• Myelin sheath


  Lipid (fat) wrapped around axon
• Myelin sheath in the CNS

  Produced by oligodendrocytes
• Myelin sheath in the PNS

  Produced by Schwann cells
• Myelin sheath


  Increases conduction velocity
• Nodes of Ranvier


  Gaps between myelin, increase conduction velocity
• Synapse


  Junction where communication between neurons occurs
• Types of synapses


  • Electrical
  • Chemical
• Chemical synapse


  • Releases neurotransmitter (chemical signal) from axon terminal
  • Contains synaptic vesicles (little packets of neurotransmitter)
• Pre-synaptic neuron


  Neuron BEFORE the synapse
• Post-synaptic neuron


  Neuron AFTER the synapse, contains receptors for neurotransmitter
• Afferent information


  Information that goes INTO the brain