worksheet3

worksheet3 - Kim Chun Kimmchun@gmail.com BIPN100, Winter...

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Kim Chun Kimmchun@gmail.com BIPN100, Winter 2008 Worksheet 3 Conduction velocity depends on _______________= length at which original signal decreases to 1/e of its original value. (exponential loss) Length constant is ___________ (inversely/directly) proportional to longitudinal resistance and ____________ (inversely/directly) proportional to membrane conductance. o Longitudinal resistance= more resistance of cytosol will give shorter length constant. o Membrane conductance= if have more conductance, decrease the length constant because of leakiness of the membrane. Myelin acts as insulator because parts of axon covered by myelin doesn’t have any ion pumps/channels. o Limits contact with ECF, therefore limiting ion leaks _________ (larger/smaller) length constant. To stop the signal, remove NT by breakdown with enzymes, or by transport back to presynaptic cell. 1. Enzymatic breakdown: ____________________ breaks down ACh to acetyl-coA and choline. a. Causes ACh concentration in synaptic cleft to decrease. b. *If ACh isn’t removed from the receptor, at first, signal will be amplified. Continued amplification leads to receptors becoming desensitized doesn’t work anymore. i. Caused by nerve gas 2. Neurotransmitters involved in depression: a. Transport back to presynaptic cell: serotonin neurotransmitter taken up by presynaptic cell with serotonin uptake transporter. i. Drugs like Prozac are _____________________ that treats depression by blocking reuptake of serotonin. b. MAO= monoamine oxidase is enzyme that breaks down noepinephrine, dopamine, serotonin. What inhibits MAO? ___________ summation= summation of different inputs. Graded potentials originate at different locations on neuron and can add together at trigger zone (axon hillock) to reach threshold. (EPSPs) ______________ inhibition= if there are two EPSPs and 1 IPSP, their sum at trigger zone can cause signal that is below threshold. o Ex: Pain pairing signals are excitatory. When rub hand in pain, it receives inhibitory synapse, which decreases the excitability of pathway. _______________ inhibition= a modulatory neuron synapses on the axon terminal of the presynaptic cell and to change amount of NT released by presynaptic cell. Divergent pathway= one neuron can have several branches affecting several other neurons. ____________ pathway= several presynaptic neurons influence a smaller number of neurons. Neurotransmitters 1. Acetylcholine has two receptors: Nicotinic receptors= agonists that activate ACh receptor. o
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This note was uploaded on 04/14/2008 for the course BIPN 100 taught by Professor French during the Winter '07 term at UCSD.

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worksheet3 - Kim Chun Kimmchun@gmail.com BIPN100, Winter...

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