Additional review Neural synapse Neurotransmitters Supplemental instruction Additional review Neural synapse Neurotransmitters Picture from http://www.humanillnesses.com/original/Conj-Dys/Depressive-Disorders.html Designed by Pyeongsug Kim ©2010 webmaster@science-i.com

Designed by Pyeongsug Kim, ©2010 www.science-i.com Synapse - The location where a neuron passes its signal to its target cell Target cell =usually another neuron, a muscle cell, or a gland cell -A synapse includes… Axon terminals of the presynaptic cell Dendrites of the postsynaptic cell or muscle cell or gland cell. Synaptic cleft Picture from http://www.humanillnesses.com/original/Conj-Dys/Depressive-Disorders.html http://www.eregimens.com/regimens/MS_Regimen.htm Designed by Pyeongsug Kim, ©2010 www.science-i.com

Designed by Pyeongsug Kim, ©2010 www.science-i.com A : B : C: 1. Mitochondria 2. 3. Autoreceptor 4. 5. 6. 7. release NT by___________ 8. NT re-uptake pump Neuron (Presynaptic) Neuron or cells (Postsynaptic) Neurotransmitter(NT) Synaptic vesicle Synaptic cleft C NT receptor Calcium Channel exocytosis Chemical Synapse! Designed by Pyeongsug Kim, ©2010 www.science-i.com

Designed by Pyeongsug Kim, ©2010 www.science-i.com 1. 2. 3. 4. 5. Synaptic Transmission Action potentials reach at the axon terminal. VG-Ca2+ channels open. Ca2+ activates calmodulin. Calmodulin activates a protein kinase. Protein kinase promote fusion and exocytosis of vesicles. The presynaptic neuron uses neurotransmitters(NT) to send the signal across the synaptic cleft. The NTs diffuse across the cleft to the dendrites of the postsynaptic cell. Designed by Pyeongsug Kim, ©2010 www.science-i.com

Designed by Pyeongsug Kim, ©2010 www.science-i.com Picture from http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=neurosci&part=A570&rendertype=figure&id=A576 Designed by Pyeongsug Kim, ©2010 www.science-i.com

Designed by Pyeongsug Kim, ©2010 www.science-i.com In the postnaptic cell…….. -NTs bind receptor proteins on the dendrites.  Cause ion channels open. If the channel is for Na+ Na+ (enter/ get out of ) the cell. (EPSP/ IPSP) will occur If the channel is for K+ K+ (enter/ get out of ) the cell. (EPSP/ IPSP) will occur If the channel is for Cl- Cl- (enter/ get out of ) the cell. (EPSP/ IPSP) will occur Designed by Pyeongsug Kim, ©2010 www.science-i.com

Designed by Pyeongsug Kim, ©2010 www.science-i.com EPSP IPSP -Exitatoy Postsynaptic Potential from one exposure to neurotransmitter -The region of positive charge inside the neuron or negative charge out of the neuron. -promote an action potential in the axon. -Inhibitory Postsynaptic Potential from one exposure to neurotransmitter -The region of negative charge inside the neuron or positive charge out of the neuron. -inhibit an action potential in the axon. Designed by Pyeongsug Kim, ©2010 www.science-i.com

Designed by Pyeongsug Kim, ©2010 www.science-i.com EPSP? IPSP? IPSP IPSP EPSP EPSP + charge? –charge? In? Out? Designed by Pyeongsug Kim, ©2010 www.science-i.com

Designed by Pyeongsug Kim, ©2010 www.science-i.com EPSPs and IPSPs summate.  if membrane potential in postsynaptic cell reaches threshold at the axon hillock, a new AP is generated.  if not, no AP occur. Designed by Pyeongsug Kim, ©2010 www.science-i.com

Designed by Pyeongsug Kim, ©2010 www.science-i.com Neurotranmitters 1) Acetylcholine -Choline Some CNS neurons(excitatory) Many PNS motor neurons (either excitatory or inhibitory) -Cholinergic neurons: use acetylcholine as NT -Somatic neuron :synapses on skeletal muscle :large EPSPs - stimulates muscles to contract -Preganglionic neuron in both Symp. & ParaSymp. -Postganglionic ParaSymp. -Curare blocks ACh action -Cholinergic receptors in the postsynaptic cells Designed by Pyeongsug Kim, ©2010 www.science-i.com

Designed by Pyeongsug Kim, ©2010 www.science-i.com -Cholinergic receptors Nicotinic - skeletal muscle fibers, autonomic ganglia - Directly bind to channel (Na+ in; followed by K+ out) EPSP! Muscarinic - binds smooth and cardiac muscle; glands - G-protein; open indirectly adjacent channel (K+ out)  IPSP! Designed by Pyeongsug Kim, ©2010 www.science-i.com

Designed by Pyeongsug Kim, ©2010 www.science-i.com Monoamines act through second messenger. - dopamine - norepinephrine - serotonin Designed by Pyeongsug Kim, ©2010 www.science-i.com

Designed by Pyeongsug Kim, ©2010 www.science-i.com Neurotranmitters(monoamines) Norepinephrine - catecholamines - works both CNS and PNS -fight-or-flight response -postganglionic Sym. stimulate cardiac muscle, cardiac muscle, some glands Picture from: Dr. Wright Bio6 slide http://www.thecausewayretreat.com/blog/2009/06/fight-or-flight-response/ Designed by Pyeongsug Kim, ©2010 www.science-i.com

Designed by Pyeongsug Kim, ©2010 www.science-i.com Neurotranmitters(Monoamines) 2) Dopamine - Monoamines -Nigrostriatal dopamine system :originates in the substantia nigra :involved in motor control. :Degeneration of this system causes ________________ L-DOPA and MAO inhibitors - Mesolimbic dopamine system :involved in behavior and emotional reward :Most addictions activate this system Overactivity contributes to _____________ anti-dopamine drugs! Parkinson's disease schizophrenia Designed by Pyeongsug Kim, ©2010 www.science-i.com

Designed by Pyeongsug Kim, ©2010 www.science-i.com Neurotranmitters (Monoamines) 3) Serotonin - Involved in regulation of mood, behavior, appetite and cerebral circulation - SSRIs (serotonin-specific reuptake inhibitors) - as antidepressants - Prozac, Zoloft Picture from http://www.humanillnesses.com/images/hdc_0000_0001_0_img0054.jpg Designed by Pyeongsug Kim, ©2010 www.science-i.com

Designed by Pyeongsug Kim, ©2010 www.science-i.com Picture from http://www.brookscole.com/chemistry_d/templates/student_resources/0030223180_garrettgrisham/HotTopics/prozac.html Designed by Pyeongsug Kim, ©2010 www.science-i.com

Designed by Pyeongsug Kim, ©2010 www.science-i.com Enteric nervous system (ENS) -efferent nervous system (PNS) -directly controls the gastrointestinal system -May be considered ANS(Autonomic nervous system) Designed by Pyeongsug Kim, ©2010 www.science-i.com

Designed by Pyeongsug Kim, ©2010 www.science-i.com Glutamic acid -the most common neurotransmitter in the brain -always excitatory -Receptors that increase the flow of positive ions by opening ion-channels eg) NMDA(or NMDAR) receptor & AMPA receptors  LTP (Long-Term Potentiation) ~ crucial to some forms of learning & memory. -concentrated in the cerebral cortex (hippocampus, amygdala, & basal ganglia -When Mg2+ block the NMDA channel, AMPA allows Na+ in.  AMPA cause depolarization enough to expel Mg2+.  Na+ & Ca2+ in through NMDA.  EPSP!!! Designed by Pyeongsug Kim, ©2010 www.science-i.com

Designed by Pyeongsug Kim, ©2010 www.science-i.com Glycine -makes the post-synaptic membrane more permeable to Cl- ion.  Hyperpolarization! (IPSP) -Spinal cord, Brain stem -GlyR (Glycine receptor) -Glycine-gated chloride channels Designed by Pyeongsug Kim, ©2010 www.science-i.com

Designed by Pyeongsug Kim, ©2010 www.science-i.com Tryptophan(serotonin) -Found in both CNS & PNS (enteric nervous system) -regulation of mood, appetite, sleep, muscle contraction, and some cognitive functions including memory and learning. -the serotonin in the brain is independently synthesized from tryptophan transported across the blood-brain barrier. -Raphe nuclei -5-HT receptors ~ EPSP or IPSP ~G protein-coupled receptors, cAMP(2nd messenger) Designed by Pyeongsug Kim, ©2010 www.science-i.com

Designed by Pyeongsug Kim, ©2010 www.science-i.com Arginine (nitric oxide) -does not bind to surface receptors -readily diffuses across cell membranes -increase cGMP(2nd messenger) -Parasymphethetic neurons Enteric nervous system(ENS) -Relaxation of smooth muscle (=inhibition of smooth muscle contraction) -vasodilation Designed by Pyeongsug Kim, ©2010 www.science-i.com

Designed by Pyeongsug Kim, ©2010 www.science-i.com