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

2024
Views:

267

Pages:

27
Author:

aprivantuqy

II Neurotransmitters and receptors 14 Basic Concepts of NT and receptor Neurotransmitter: Endogenous signaling molecules that alter the behaviour of neurons or effector cells. Neuroreceptor: Proteins on the cell membrane or in the cytoplasm that could bind with specific neurotransmitters and alter the behavior of neurons of effector cells 15 •Vast array of molecules serve as neurotransmitters •The properties of the transmitter do not determine its effects on the postsynaptic cells •The properties of the receptor determine whether a transmitter is excitatory or inhibitory 16 A neurotransmitter must (classical definition) • • • • • Be synthesized and released from neurons Be found at the presynaptic terminal Have same effect on target cell when applied externally Be blocked by same drugs that block synaptic transmission Be removed in a specific way 17 Agonist A substance that mimics a specific neurotransmitter, is able to attach to that neurotransmitter's receptor and thereby produces the same action that the neurotransmitter usually produces. Drugs are often designed as receptor agonists to treat a variety of diseases and disorders when the original chemical substance is missing or depleted. 18 Antagonist Drugs that bind to but do not activate neuroreceptors, thereby blocking the actions of neurotransmitters or the neuroreceptor agonists. 19 • Same NT can bind to different -R • different part of NT ~ NT Receptor A Receptor B 20 Specificity of drugs Drug A Receptor A Drug B NT Receptor B 21 Five key steps in neurotransmission • Synthesis • Storage • Release • Receptor Binding • Inactivation 22 Synaptic vesicles • Concentrate and protect transmitter • Can be docked at active zone • Differ for classical transmitters (small, clear-core) vs. neuropeptides (large, dense-core) 23 Neurotransmitter Co-existence (Dale principle) Some neurons in both the PNS and CNS produce both a classical neurotransmitter (ACh or a catecholamine) and a polypeptide neurotransmitter. They are contained in different synaptic vesicles that can be distinguished using the electron microscope. The neuron can thus release either the classical neurotransmitter or the polypeptide neurotransmitter under different conditions. 24 25 Receptors determine whether: • Synapse is excitatory or inhibitory – NE is excitatory at some synapses, inhibitory at others • Transmitter binding activates ion channel directly or indirectly. – Directly • ionotropic receptors • fast – Indirectly • metabotropic receptors • G-protein coupled • slow 26 Receptor Activation • Ionotropic channel – directly controls channel – fast • Metabotropic channel – second messenger systems – receptor indirectly controls channel ~ 27 (1) Ionotropic Channels Channel NT neurotransmitter 28 Ionotropic Channels NT Pore 29 Ionotropic Channels NT 30 Ionotropic Channels 31 Metabotropic Channels • Receptor separate from channel • G proteins • 2nd messenger system – cAMP – other types • Effects – Control channel – Alter properties of receptors – regulation of gene expression ~ 32 G protein: direct control • NT is 1st messenger • G protein binds to channel – opens or closes – relatively fast ~ 33 G protein: direct control R G GDP 34 G protein: direct control R G GTP Pore 35 G protein: Protein Phosphorylation A C R G GDP PK 36 G protein: Protein Phosphorylation A C R G ATP GTP cAMP PK 37 G protein: Protein Phosphorylation A C R G ATP GTP P cAMP PK Pore 38 Transmitter Inactivation • • • • • • Reuptake by presynaptic terminal Uptake by glial cells Enzymatic degradation Presynaptic receptor Diffusion Combination of above 39 Summary of Synaptic Transmission 40

II Neurotransmitters and Receptors

II Neurotransmitters and Receptors - Page 3

II Neurotransmitters and Receptors - Page 4

II Neurotransmitters and Receptors - Page 5

II Neurotransmitters and Receptors - Page 6

II Neurotransmitters and Receptors - Page 7

II Neurotransmitters and Receptors - Page 8

II Neurotransmitters and Receptors - Page 9

II Neurotransmitters and Receptors - Page 10

II Neurotransmitters and Receptors - Page 11

II Neurotransmitters and Receptors - Page 12

II Neurotransmitters and Receptors - Page 13

II Neurotransmitters and Receptors - Page 14

II Neurotransmitters and Receptors - Page 15

II Neurotransmitters and Receptors - Page 16

II Neurotransmitters and Receptors - Page 17

II Neurotransmitters and Receptors - Page 18

II Neurotransmitters and Receptors - Page 19

II Neurotransmitters and Receptors - Page 20

II Neurotransmitters and Receptors - Page 21

II Neurotransmitters and Receptors - Page 22

II Neurotransmitters and Receptors - Page 23

II Neurotransmitters and Receptors - Page 24

II Neurotransmitters and Receptors - Page 25

II Neurotransmitters and Receptors - Page 26

II Neurotransmitters and Receptors - Page 27

of 27

Description

Free up your schedule!

Take 5 seconds to unlock