Electrical Impulses

In my AP Biology class, we are currently learning about a subject that I find very interesting: the process by which a signal can be passed from a nerve to the brain and vice versa. When I heard people refer to these signals as "electrical impulses," I never knew what they meant. How did electricity get inside the body? However, I am now aware of how such processes occur. First, allow me to discuss the nature of a neuron. Basically, there is a cell body, known as a soma. This is where the cell nucleus is located. Stemming from one side of the soma are dendrites, little arms that connect to the previous neurons. On the other end is the axon. This is a long arm that branches into smaller, collateral axons, that then connect to other neurons' dendrites. Between each axon and each dendrite is a synapse, a gap between neurons that allow for a signal to be passed. When a sensory neuron receives an impulse, say heat, channels on its axon open up and allow positively charged ions to flow in and negatively charged ions to flow out. This transfer of electrons is what is known as the electrical impulse. When enough electricity has been generated, the neuron is said to have reached "threshold," and the electrical signal is passed down the axon to be transferred to the next neuron's dendrites. When this happens, one of two things can occur. If the neurons are connected by a chemical synapse, the electrical impulse triggers the axon to release neurotransmitters into the synapse. These neurotransmitters bond to receptors on the proceeding dendrite, and when enough receptors have been activated, the impulse is passed on. However, if the neurons are connected by an electrical synapse, the electrical signal is simply passed over from the axon to the dendrite. So this process occurs over and over until the signal reaches the brain. Then, the brain illicits the appropriate response and sends it back to the location of the body that was affected via motor neurons. If we use the example of heat again, the brain would signal the motor neurons to contract the muscles near the heat and retreat. This is how electrical impulses allow our body to function.