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Oxyde nitrique

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Oxyde nitrique

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  1. Loewi's experiment demonstrating chemical neurotransmission. (A) Diagram of experimental setup. (B) Where the vagus nerve of an isolated frog's heart was stimulated, the heart rate decreased (upper panel). If the perfusion fluid from the stimulated heart was transferred to a second heart, its rate decreased as well (lower panel).

  2. Demonstrating the identity of a neurotransmitter at a synapse requires showing (1) its presence, (2) its release, and (3) the postsynaptic presence of specific receptors.

  3. Demonstrating the identity of a neurotransmitter at a synapse requires showing (1) its presence, (2) its release, and (3) the postsynaptic presence of specific receptors.

  4. Demonstrating the identity of a neurotransmitter at a synapse requires showing (1) its presence, (2) its release, and (3) the postsynaptic presence of specific receptors.

  5. Les amines biogènes Acides aminés Peptides Others Acetylcholine Glutamate Monoamines GABA ATP Oxyde nitrique Substance P Sérotonine Catécholamine Dopamine Noradrénaline Adrénaline Neurotransmetteurs à petites molécules

  6. B) Small-molecule neurotransmitters are synthesized at nerve terminals. The enzymes necessary for neurotransmitter synthesis are made in the cell body of the presynaptic cell (1) and are transported down the axon by slow axonal transport (2). Precursors are taken up into the terminals by specific transporters, and neurotransmitter synthesis and packaging take place within the nerve endings (3). After vesicle fusion and release (4), the neurotransmitter may be enzymatically degraded. The reuptake of the neurotransmitter (or its metabolites) starts another cycle of synthesis, packaging, release, and removal (5).

  7. (C) Peptide neurotransmitters, as well as the enzymes that modify their precursors, are synthesized in the cell body (1). Enzymes and propeptides are packaged into vesicles in the Golgi apparatus. During fast axonal transport of these vesicles to the nerve terminals (2), the enzymes modify the propeptides to produce one or more neurotransmitter peptides (3). After vesicle fusion and exocytosis, the peptides diffuse away and are degraded by proteolytic enzymes (4).

  8. Acetylcholine metabolism in cholinergic nerve terminals. The synthesis of acetylcholine from choline and acetyl CoA requires choline acetyltransferase. Acetyl CoA is derived from pyruvate generated by glycolysis, while choline is transported into the terminals via a Na+-dependent transporter. After release, acetylcholine is rapidly metabolized by acetylcholinesterase and choline is transported back into the terminal.

  9. 5- action nicotinique 5.1 proprietes des récepteurs nicitiniques Conditions ioniques Intérieur 160 mM K, 3 Na, 163 Cl- Extérieur 160 Na, 3 K, 165 Cl-

  10. Current evoked by nicotine in cultured rat superior cervical ganglia. The cell membrane potentials were held at _70 mV.

  11. Name: CurareGenus: ChondrodendronSpecies: tomtosum

  12. Series of endplate potentials/action potentials in frog muscle under the increasing effect of a concentration of tubocurarine added at b. As endplate potential falls below threshold, action potential fails and there is no mechanical response. Series summarized in h.

  13. GABA Acétyl choline Clostridium botulinum

  14. Traitement de la myasténie grave

  15. Potentiel d’action ACh Na+ K+ R M2 + + + + + + + - - - - - - - AC - + + + + + = bg a Ca2+ K+ Ca2+ - Na+ Na+ AMPc ATP ATP ADP -

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