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Neurons Speak The Neuron is the Fundamental “working unit” of the nervous system In most respects the neuron is like other cells of our body But is different in that it can produce electrical impulses near its cell body region That move down the axon and lead to the release of specialized neurochemicals (neurotransmitter substances) at the Synapse Synaptic release of Neurotransmitter substances may in turn affect “postsynaptic” neurons; mostly in the dendritic regions The Neuron is also different in that the axon is typically myelinated by “glial cells” The Neuronal communication process can be thought of as an “electro-chemical” event • How is the electric signal produced? • How is the Chemical event produced? The Neuron is Like a little battery The resting Membrane potential (RMP) Ions are responsible for the charge of a neuron Cations + Anions- At Rest, ionic substances have different concentrations inside vs. outside the neural membrane The forces of Diffusion: Concentration Gradients “Threshold” triggers the “Action Potential” By activating Ion channels Once triggered, the AP is all or none, and “one-way.” Myelenation and size affect speed Action Potential at the Terminals The Synapse: PRESYNAPTIC and POSTSYNAPTIC processes PRESYNAPTIC Exocytosis Classical NTs NTs Terminology Post synaptic effects Acetylcholine/ACH Cholinergic Serotonin/5-HT serotonergic GABA (gamma-amino-butyric acid) GABA-ergic Glutamate/Glu Glutamatergic Norpinephrine /NEAdrenergic Dopamine /DA Dopaminergic Enkephalin/Endorphin +/+/- + +/- +/+/- Many other neurotransmitters are derived from precursor proteins, the so-called peptide neurotransmitters. As many as 50 different peptides have been shown to exert their effects on neural cell function. POSTSYNAPTIC PROCESSES: NT receptors Specificity- Lock and Key analogy EFFECTS OF NTs? Many factors, but all lead to: • IPSPs: inhibiitory post synaptic potentials – Decrease probability of action potential • EPSPs: excitatory post synaptic potentials – Increase probability of action potential Neural Integration NT-receptor interactions must stop! Enzymatic degradation Eg… Effects of Nerve gas exposure Neuromuscular Effects •Twitching •Weakness •Paralysis •Respiratory failure Autonomic Nervous System Effects •Reduced Vision •Small pupil size •Drooling •Sweating •Diarrhea •Nausea •Abdominal pain •Vomiting Central Nervous System Effects •Headache •Convulsions •Coma •Respiratory arrest •Confusion •Slurred speech •Depression •Respiratory depression Reuptake Here are the SSRIs approved by the Food and Drug Administration (FDA) specifically to treat depression, with their generic, or chemical, names followed by available brand names in parentheses: Citalopram (Celexa) Escitalopram (Lexapro) Fluoxetine (Prozac, Prozac Weekly) Paroxetine (Paxil, Paxil CR, Pexeva) Sertraline (Zoloft) These medications may also be used to treat conditions other than depression. Side effects of SSRIs All SSRIs have the same general mechanism of action and side effects. However, individual SSRIs have some different pharmacological characteristics. That means you may respond differently to certain SSRIs or have different side effects with different SSRIs. SSRI possible side-effects Side effects of SSRIs include: Nausea Sexual dysfunction, including reduced desire or orgasm difficulties Dry mouth Headache Diarrhea Nervousness Rash Agitation Restlessness Increased sweating Weight gain Drowsiness Insomnia Drugs may affect neural transmission in different ways