Nanobiology Notes

Perkinjes and Granules and Schwanns, oh my...

It's tempting to oversimplify things. Like neurons. It would be nice if there were one type of neuron, and all you needed to know about how neurons work could be clearly labelled on a diagram of that one type of neuron. Well, nature LOVES to specialize. So, before getting deeper into how neurons work, I thought it would be good to take a step back and get some vocabulary in place...The BasicsFrom University of Washington's 'Neuroscience for kids':Neurons come in many different shapes and sizes. Some of the smallest neurons have cell bodies that are only 4 microns wide. Some of the biggest neurons have cell bodies that are 100 microns wide. Neurons are similar to other cells in the body because: Neurons are surrounded by a cell membrane. Neurons have a nucleus that contains genes. Neurons contain cytoplasm, mitochondria and other "organelles". Neurons carry out basic cellular processes such as protein synthesis and energy production. However, neurons diff…

Neurotransmitters - molecular messages

You often hear about neurotransmitters in the news and in science magazines in a kind of off-hand way that assumes everyone must surely know what these things are. But, um, what are they, exactly?

From Sandra Ackerman's book "Discovering the Brain": To be recognized as a neurotransmitter, a chemical compound must satisfy six conditions: It must be

synthesized in the neuron, stored there, released in sufficient quantity to bring about some physical effect; when administered experimentally, the compound must demonstrate the same effect that it brings about in living tissue; there must be receptor sites specific to this compound on the postsynaptic membrane, as well as a means for shutting off its effect, either by causing its swift decomposition or by reuptake, absorbing it back into the cell.

OK, well, what about hormones? They're chemical messengers too - how are hormones different from neurotransmitters? A hormone, by definition, is a compound produced by an endocrine…

Receptors - getting the message across

From Paul Greengard's Nobel Lecture in 2000:
It is estimated that there are about 100 billion nerve cells in the brain and that on average each of these nerve cells communicates with 1000 other nerve cells. A vigorous debate went on from the 1930s through the 1960s as to whether intercellular communication across the synapses between nerve cells was electrical or chemical in nature. The electrical school of thought held that the nerve impulse or action potential was propagated along the axon to the nerve ending, changed the electrical field across the postsynaptic plasma membrane, and thereby produced a physiological response. The chemical school believed that when the action potential came down the axon to the nerve terminal, it caused the fusion of neuro-transmitter-containing vesicles with the presynaptic plasma membrane, releasing a neurotransmitter, which then diffused across the synaptic cleft and, through activation of a (hypothetical) receptor, produced a physiological resp…

Beta Rhythm (Music of the Mind)

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