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 AcetylcholineAcetylcholine/ACH Cholinergic+/- SerotoninSerotonin/5-HTserotonergic+/- GABAGABA (gamma-amino-butyric acid) GABA-ergic- Glutamate/GluGlutamatergic+ NorpinephrineNorpinephrine /NEAdrenergic+/- DopamineDopamine /DADopaminergic+/- 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 Autonomic Nervous System Effects Central Nervous System Effects Twitching Weakness Paralysis Respiratory failure Reduced Vision Small pupil size Drooling Sweating Diarrhea Nausea Abdominal pain Vomiting 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