![]() ![]() part of the cell that controls what can get in and out of the cell. Since we are made up of mostly water, including the fluids that surround all the cells in our body, this results in the phospholipids separating and keeping the cell’s innards inside and the rest of the world outside.Ĭomputer illustration of a cutaway view of a human cell membrane. ![]() It is made up of molecules called phospholipids, long chains of carbon that interact with each other creating an internal environment inside the membrane that repels water (a hydrophobic environment), and surface molecules capable of interacting with water (a hydrophilic environment). It separates everything inside the cell from everything outside. The cell membrane is like the ‘skin’ of a cell. This is a building block principle we will refer back to over and over again. The first fundamental thing to understand is what an electrical impulse means - what it physically is - in a neuron, or for that matter, in any cell capable of sustaining electrical activity. The physical basis of electrical impulses in cells Which in turn puts us back at the dendrites of the next set of neurons, and back to signaling via electrical impulses. It is a biochemical mechanism that takes over - triggered by the arrival of the action potential - which in turn passes the signal across the synapse to the next neuron. In fact, as introduced above, what happens at the synapse is not electrical at all. And the events at the synaptic terminals when the action potential reaches the end of the axon are completely different than what is taking place in either the dendrites or the axon. The electrical impulses in the dendrites are functionally and biophysically different than the action potentials in the axon. So in a series of articles we will explore each one. Anywhere on the circle, since a neuron receiving signals from other upstream neurons is eventually passing those signals off to other neurons downstream.īut the details matter. So to understand how neurons communicate with each other we have to start somewhere. It does not matter where on the circle you start, you can start anywhere, go around, and you end up back in the same place. Your mind, as far as we know, is the result of the physical processes in your brain and all the action potentials and other cellular signals responsible for collectively carrying and processing all the information the brain contains. What you think, how you interact with the physical world through your senses, what you imagine, how you feel, how you learn, and how you remember. ![]() The result is, well, you and who you are. In this way, billions upon billions upon billions of signals independently and simultaneously propagate through the entire brain across the massive network of 85 billion neurons. The signal that crosses over at the synapse to other neurons is not as an electrical impulse, but rather a chemical message that then triggers new electrical impulses in the dendrites of the downstream neurons, just one of as many as tens to hundreds of thousands such inputs simultaneously occurring on the dendrites. ![]()
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