University:
Kentucky State University
Course:
BIO 303 | Human Physiology
Academic year:

2020
Views:

139

Pages:

15
Author:

rezancuk2j

Synapses and Neurotransmitters Communication Between Neurons • Synapse: A specialized site of contact, and transmission of information between a neuron and an effector cell Anterior Motor Neuron Figure 45-5 Communication Between Neurons • Electrical synapse Chemical synapse Action of Neurotransmitter on Postsynaptic Neuron • Two types of receptors – Ion channels receptors Ionotropic – Second messenger receptors Metatropic Ion Channels receptors • transmitters that open sodium channels excite the postsynaptic neuron. • transmitters that open chloride channels inhibit the postsynaptic neuron. • transmitters that open potassium channels inhibit the postsynaptic neuron. Seconded messenger receptors (as example G-protein) 1. Opening specific ion channels 2. Activation of cAMP or cGMP 3. Activation of one or more intracellular enzymes 4. Activation of gene transcription. Ion Channel G-Protein-Coupled Receptors and Effectors • GPCR Effector Systems (Cont’d) • Push-pull method (e.g., different G proteins for stimulating or inhibiting adenylyl cyclase) G-Protein-Coupled Receptors and Effectors • GPCR Effector Systems (Cont’d) • Some cascades split – G-protein activates PLCà generates DAG and IP3à activate different effectors G-Protein-Coupled Receptors and Effectors • GPCR Effector Systems (Cont’d) • Signal amplification Drugs and the Synapse 1) at the receptor • The study of the influence of various kinds of drugs has provided us with knowledge about many aspects of neural communication at the synaptic level. • Drugs either facilitate or inhibit activity at the synapse. – Antagonistic drugs block the effects of neurotransmitters (e.g., novacaine, caffeine). – Agonist drugs mimic or increase the effects of neurotransmitters (e.g., receptors in the brain respond to heroin, LSD and cocaine) – Allosteric modulation Agonists and Antagonists Allosteric modulation Benzodiazepines potentiate GABA-induced responses Synaptic Transmission Drugs and the Synapse 2) alter various stages of synaptic processing. • Drugs work by doing one or more of the following to neurotransmitters: 1. 2. 3. 4. 5. 6. Increasing the synthesis. Causing vesicles to leak. Increasing release. Decreasing reuptake. Blocking the breakdown into inactive chemical. Directly stimulating or blocking postsynaptic receptors.