Bio 224 theme 5

  1. Central nervous system 
    Brain and spinal cord in vertebrates
  2. Peripheral nervous system
    (PNS) All neurons and projections of their plasma membranes that are outside of the CNS
  3. Grey matter
    • the major component of the CNS, consisting of:
    • Neuronal cell bodies, dendrites and axons;
    • Glial cells;
    • Capillaries;

  4. White matter,
    • mostly contains myelinated axon tracts
    • The color difference arises mainly from the whiteness of myelin.
  5. Neurons
    • Generate, send and receive information
    • through electrical and
    • chemical signals;
    • to and from other neurons or other cells throughout the body
  6. What animals don't have neurons?
  7. What cells can be excitable
    neurons, muscle cells, and endocrine cells, as well as in some plant cells
  8. What is the voltage for:
    action potential?
    threshold potential?
    What is the resting potential?
    • +30mV
    • -50mV
    • -70mV
  9. What effect do action potentials have on muscle cells?
    B-cells in pancreas?
    • -an action potential is the first step in the chain of events leading to a contraction
    • -release of insulin
  10. What makes up dendrites and axons?
    Plasma membrane
  11. what part of a neuron contains the nucleus and organelles?
    the cell body or soma
  12. Dendrites
    Branched projections of a neuron that conduct the electrochemical stimulation received from other neural cells.
  13. Axons
    • -Long, slender projection of neurons
    • -Conducts electrical impulses away from the soma;
    • -rich in voltage-gated ion channels
  14. Synapses
    • -place of transmission of neurotransmitters/electrical impulse, from axon to dendrite
    • -full of neurotransmitter vesicles
    • -Dendrite receptor is loaded with ligand gated ion channels
  15. Glial Cells or Neuroglia
    • •Non nervous cells of the NS
    • –commonly known as the glue of the NS
  16. What are the ratios of Glial cells to neurons in the brain
    • roughly 1:1
    • in cerebellum 3:2
  17. What are the six types of Glial cells
    • 1.Astrocytes
    • 2.Microglia
    • 3.Ependymal cells
    • 4.Oligodendrocytes
    • 5.Satellite cells
    • 6.Schwann cells
  18. Astrocytes
    –star-shaped glial cells–provision of nutrients–maintenance of extracellular ion balance; –repair and scarring process of the brain and spinal cord; and–biochemical support of endothelial cells
  19. The Blood brain Barrier (BBB)
    -effect on different molecules
    • •A separation between the circulating blood and the brain extracellular fluid;
    • •Consist of tight junctions around the capillaries that do not exist in normal circulation;
    • –Restrict the diffusion of microscopic objects, e.g.•bacteria and large or hydrophilic molecules into CSF;
    • •while allowing the diffusion of small hydrophobic molecules (O2, CO2, hormones).
    • –Actively transport metabolic products such as glucose Image Upload 1
  20. Schwann cells
    • •The principal glia cells of the PNS
    • -Wrap around axons of motor and sensory neurons to form the myelin sheath
  21. Myelin
    • •;An electrically inulating material that forms a layer around axons
    • •Essential for the proper functioning of the nervous system;
    • •Composed of:
    • – ~ 80% lipids, primarily the glycolipids galactocerebroside
    • –~20% protein
    • •myelin basic protein (MBP),
    • •myelin oligodendrocyte glycoprotein (MOG), •proteolipid protein (PLP).
  22. Schwann cells myelinate the _NS
    Oligodendrocytes myelinate the _NS
    Schwann cells myelinate the PNS Oligodendrocytes myelinate the CNS
  23. Three Main Types of Neurons
    • •Interneurons or Association Neurons
    • •Motor neurons
    • •Sensory neurons
  24. Interneurons or Association Neurons
    • –Form interconnections between other neurons in the CNS;
    • –Tend to have many dendrites;
    • –Axons are typically short and highly branched allowing them to form complex connections with other cells
  25. •Motor neurons
    –Efferent: send signals away from CNS to elicit response
  26. •Sensory neurons
    • –Afferents: detect information from the outside world or internal body conditions & transmit to the CNS;
    • –Usually a large axon that bypasses the cell body and goes directly to the CNS
  27. Reflex Circuits
    • •The stimulus from sensory neurons is sent to the CNS, but there is little or no interpretation of the signal;
    • –Few interneurons are involved
    • •The signal is then transmitted to motor neurons, which elicit a response, such as a knee jerk
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Bio 224 theme 5
Bio 224