Electrical Signals

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Electrical Signals
2010-11-03 18:50:53
bsci207 electrical signals neurons

Electrical signals
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  1. Intensity
    • Series of very rapid memrane potentials if intense stimulus.
    • Intensity is encoded in nervous system as frequency.
    • Axons all generate the same potential
  2. Myelin Shealth
    • type of electrical insulation.
    • Mylelination precents ions from leaking out across the plasma membrane
    • Electrical signals jump down the myelinated axon much faster than they can move down an unmyelinated axon
  3. Hyperpolarization
    • Refractory period
    • Repolarization event results in mebrane becoming more negative than the resting potential
    • Nothing can invoke another action potential until the period is over- usually a few milliseconds
  4. Repolarization
    Membrane potential reaches about +40 mV, certain ion channels close and other ion channels in the membrane open. Ions flow outside of the cell rapidly and the charges on the two sides become more different
  5. Threshold potential
    • The mebrane potential that will trigger an action potential in a neuron or other excitable cell.
    • Once this point is reached, certain channels in the axon membrane open and ions rush into the axon, following their electrochemical gradients.
    • Current flow causes further depolarization-inside of membrane becomes less negative and then positive with respect to the outside
  6. Depolarization
    • initial event in action potential where the membrane becomes less polarized than before (changes on two sides of membrane becomes less different)
    • Membrane must depolarize from a resting potential of -65 mV to about -55 mV for an action potential to begin.
  7. Action potentials
    All or none changes in the membrane graded by electrical signals. An inflow of sodium ions is followed by an outflow of potassium ions.
  8. Voltage
    • ellectrical potential difference across plasma membrane.
    • exists due to differences in concentrations od ions on the two dies of the plasma membrane
  9. Brain
    • a somewhat vague term usually reffering to the anterior enlargement of the CNS, sometimes mistakenly used and refered to as cerebral ganglia
    • White matter actually integrates the information in the white mylein
  10. Neurophil
    a region of the CNS dominated by synapses, usually without axons or cell bodies ( a region of neural intergration)
  11. Nucleus
    A cluster of neuron cell bodies located inside the CNS
  12. Ganglion
    a cluster of neuron cell bodies located outside the CNS
  13. Tract
    A collection of axons traveling together inside the CNS
  14. Nerve
    a collection of axons traveling together outside the CNS
  15. Efferent Nerve or Neuron (motor neuron)
    Conducts informations from the CNS to the body (muscles, glands)
  16. Afferent nerve or neuron (Sensory neuron)
    Conducts information from the body (sense organs) to the CNS
  17. Peripheral Nervous System (PNS)
    portion of the nervous system that delivers sensory input from and delivers neural signals to specific regions of the body
  18. Central Nervous System (CNS)
    portion of the nervous system that intergrates infromation from throughout the body and cordinates whole organism behavior
  19. Nerve Net
    A network of neurons without a central nervous system
  20. Electrical Signals
  21. Motility depends on the ability of animals to conduct impulses throughout the body with electrical
    • signals (concentration gradients of charged particles)