Week 2 material

Cards (70)

  • What is the flow of the signal in nervous system?
    dendrites to cell body to axon to axon terminal to next cell via synapse
  • Microtubules
    backbone of an axon
  • afferent neurons

    Nerve cells that carry impulses towards the central nervous system
  • efferent neurons
    Nerve cells that conduct impulses away from the central nervous system
  • interneurons
    Central nervous system neurons that internally communicate and intervene between the sensory inputs and motor outputs
  • Glial Cells
    make up 90% of the cells in the nervous system. They don't convey information. Rather they serve to support nerve cells
  • Schwann cells
    myelinate peripheral neurons (PNS)
  • Oligodendendrocytes
    myelinate CNS neurons
  • Ependymal cells
    Form sheets that line the brain ventricles (cavities)
  • Astrocyte
    control composition of CNS extracellular fluid (ion and glucose concentration, permeability of capillaries)
  • Microglia
    immune functions in brain
  • voltage gated channels
    open and close in response to changes in membrane voltage potential
  • ligand gated channel
    Open in response to binding of small chemical messengers
  • What two forces do you need to consider when ions are moved in or out of cell?
    Concentration gradient and electrical potential
  • membrane potential
    By convention the ECF is defined as zero voltage, so the excess of + or - charges in the cell defines this
  • Electrical potential
    The ability (used or not) to move electrical charges (units of volts, V)
  • electrical current

    When charges move this is the result (I)
  • Ohm's Law
    I = V/R where for a given potential, the amount of current will be a function of the resistance (R) of the media
  • Resistance (R) in Ohm's law
    For a cell, it is a function of the number of open ion channels
  • Which ion are cells more permeable to and why?
    More permeable to K+ than Na+ because of leak channels
  • What does the Na+/K+ ATPase maintain?
    Resting potential of the cell. Unequal transport of 3Na+ out and 2K+ in generates part of the membrane potential
  • When is a cell at equilibrium potential?
    force of the concentration gradient and the electrical potential exactly balance each other out. There is no net movement of ions in and out of cells
  • Nernst equation
    E(ion) = 61/z * log[ C out / C in ]
    Finds the equilibrium potential of a given ion in mVolts. Tells how much electrical potential could build up given the concentration differences
  • Driving force
    Determines if an ion will enter or exit a cell
    Driving force = membrane potential - ion potential
  • What does a negative DF mean?

    A cation will enter the cell while an anion will exit the cell
  • What does a positive DF mean?

    An anion will enter the cell while a cation will exit the cell
  • What does it mean if membrane potential is equal to ion potential
    No net movement will occur
  • resting potential
    Membrane potential of a neuron or other excitable cell when it is not signaling. Characterized by higher K+ permeability than Na+ permeability
  • Synapse
    Points of connection between neurons
  • Convergence
    One nerve cell can have thousands of of synaptic inputs
  • Divergence
    One nerve cell can contact many other cells at synapses
  • What are the two types of synapses?
    chemical and electrical
  • Electrical synapse
    simpler, less abundant, and faster than chemical synapses
    the cytoplasm of the pre- and post-synaptic cells are joined by gap junctions.
    Proteins called connexins form hollow tubes that allow for cytoplasms of adjacent cells to be interconnected. This allows direct flow of current from one cell to the next.
    Electrical synapses are found in neural systems that require the fastest possible response (example is defensive reflexes) and are used for simple behaviors.
  • Chemical synapse
    Involve a synaptic cleft/gap where a neurotransmitter (chemical signal) is released into it due to the arrival of an action potential to the axonal terminus. The neurotransmitter then binds to a receptor on the post-synaptic cells which may cause either depolarization or hyperpolarization. There is a brief delay in synaptic transmission because of the time it takes for the release, diffusion, and binding of the neurotransmitter.

    Chemical synapses allow for the biological computations that underlie both unconscious behaviors and conscious thought.
  • Acetylcholine (Ach)

    Excitatory neurotransmitter
    Two types of receptors: nicotinic, muscarinic
    Regulation of muscle movement
  • Dopamine (DA)

    A catecholamine (synthesize from tyrosine) that acts in a reward pathway in the central nervous system
  • Norepinephrine (NE)

    A catecholamine (synthesize from tyrosine) that is involved in the fight or flight response
  • Epinephrine
    A catecholamine (synthesize from tyrosine) that usually acts as a hormone and has similar effects to norepinephrine
  • Serotonin
    Derived from tryptophan, can be excitatory or inhibitory, and helps with control of mood
  • Glycine
    Inhibitory and receptor is a Cl- channel. Acts primarily in the spinal cord. It is an antioxidant and an AA