Today in BSCI 230, 3/29/01
  • Examination Next Thursday, April 5th
  • Review session:

    •     -Wednesday, 4/4, 
     
  • Have you reviewed the sample problems and the old examinations?
    •     -Do you have any questions NOW?
     
  • Begin with Photosynthesis until.....
  • BSCI 230 Fundraiser begins
    •     -Hit up friends, relatives, strangers, etc.
        -Bring in contributions
        -Checks payable to:
                    BSCI 230 AIDS Fund
        -We'll list the names of the donors of > $5.00 on our Web site
    Synapse:
    Site at which a neuron communicates with another neuron or an effector organ

    Types of Synapses:

    Chemical

    Electrical

    Note the importance of the constant number of neurotransmitter molecules per vesicle and of the constant number of vesicles released per action potential!


    Neurotransmiters & Receptors
  • Action potential reaches nerve terminal
  • Entry of extracellular Ca++ 
  • Exocytosis of neurotransmitter into synaptic cleft
  • Exocytosis
  • Receptors
  • [NT] + R<------>[NT]*R
  • NT removal
  • Graded Potential
    •     -epsp & ipsp




    Importance of action potentials having the same amplitude and duration.....

    Post Synaptic Events:Graded or Local Potential
  • Depolarization or hyperpolarization
  • Variable amplitude
    •     -Depends upon stimulus amplitude and resulting I flow
  • Variable duration


    • Graded or Local Potential
  • Not propagated
    •     -Dies out as it travels along membrane
  • Spreads in any and all directions along surface
  • Temporal and spatial summation
    • Post Synaptic Events:
    EPSP: EXCITATORY POSTSYNAPTIC POTENTIAL
    EPSP --> Depolarization -->
    Threshold -->
    Action potential -->
    Excitation of 
    Post synaptic structure
    Post Synaptic Events:
     

    INHIBITORY - IPSP
    IPSP -->
    Hyperpolarization -->
    Inhibition
    (Vm is farther away from threshold, thus more difficult to excite)

    Neurotransmitters

    CHOLINERGIC RECEPTORS

    Nicotinic
    Muscarinic
    Norepinephrine
    (noradrenaline)
    Norepinephrine Receptors
    (Adrenergic Receptors    )
    a1 -  excitatory
        (e.g., constrict blood vessels)
    a2 - inhibitory
    b1 - excitatory (increase heart rate)
    b2 - inhibitory (dilate blood vessels)