2011 Synaptic Transmission

2011 Synaptic Transmission - C - 76Dr. Kennon M. Garrett...

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Unformatted text preview: C - 76Dr. Kennon M. Garrett SYNAPTIC TRANSMISSION AND NEUROTRANSMITTERSReading: Widmaier et al., Vanders Human Physiology, 12th ed. pp. 156-168.Behavioral Objectives 1. List characteristics of excitatory and inhibitory synapses 2. List types of summation and describe their mechanism. 3. Describe how action potentials are initiated in neurons. 4. Describe mechanisms for presynaptic inhibition and presynaptic potentiation 5. Describe differences between a neurotransmitter and a neuromodulator 6. List steps involved in neurotransmitter synthesis and elimination. 7. Describe synthesis and metabolic pathways for acetylcholine, biogenic amines and nitric oxide. 8. List the biogenic amine neurotransmitters, excitatory amino acid neurotransmitters and inhibitory amino acid neurotransmitters and examples of neuropeptides. 9. Describe mechanisms of modulation of neurotransmission and examples of drugs that act by these mechanisms. I. Type of Synapses 1.CNS - multiple synapses C - 772. Axo-axonic synapses Axon making synapses with presynaptic nerve terminals. These synapses are responsible for presynaptic modulation. Figure 6-33 3. Autonomic nervous system Varicosities are located along the axon which contain act like synaptic terminals. Neurotransmitter is synthesized, stored and released from the varicosities. C - 78II. Excitatory synapsesA. Excitatory postsynaptic potentials (EPSP) the magnitude of a single EPSP is small compared to an end plate potential. Figure 6-28 Figure 6-32 B. EPSPs are produced by activation of an excitatory receptor. C. The excitatory receptors increase permeability to sodium and potassium ions D. Graded potential III. Inhibitory synapses A.Inhibitory postsynaptic potentials (IPSP) hyperpolarizing or stabilization of membrane potential C - 79Figure 6-29Figure 6-32B. Produced by activation of an inhibitory receptor C. Increase permeability to potassium or chloride ions (depending on receptor activated) D. Graded potential IV. Initiation of action potentialsA. Action potentials are initiated at the axon hillock due to high concentration of voltage- gated sodium and potassium channels. Depolarizing current from the graded potentials produced at the dendrites and cell body must flow to the axon hillock to bring it to the threshold potential. Current from a single EPSPwill depolarize the axon hillock less...
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2011 Synaptic Transmission - C - 76Dr. Kennon M. Garrett...

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