Describe the basic physiology of a neuron. Detail the manner by which neurons fire action potentials and how neurons communicate with one another across synapses. Outline the process of how an action petential occurs and hoe it propagates down an axon. Explain how chemical transmission occurs at synapses and how this allows neurons to activate of inhibit one another. [Picture from "Answer to Neuron Structure"]Neurons are the basic units of the brain. Above is a picture of a prototypical neuron with its parts labeled by number. The objects labeled by the number one are Dendrites. Dendrites conduct nerve impulses towards the nerve cell. The nucleus, which regulates activities in the cell is labelled 2. Labeled 3, the soma or cell body, is the body of the neuron. The myelinated sheath, of the structure labeled 4, acts like an insulator. Not all neurons have myelinated sheaths. In the types that do, messages to said to 'jump' along the axon. Structure 6 is the axon, which conducts impulses away from the cell body. Finally, structures labeled 8 are called terminal branches or synaptic terminals. These transfer impulses toward the next neuron. (Answer to Neuron Structure) Action potential is what allows for nerve impulses. The process of action potential begins when there is a difference in concentration of ions outside and inside of the neuron. Before this process begins, the neurons are in a state called resting potential. In this state, neurons are negativelty charged at -70 mv. If an electrical stimulus is applied, sodium dependent gates open and positive sodium ions to rush in. Now the neuron is positively charged. The added sodium creates what is known as a 'spike'. This occurs, on average, at positive 35mv. Following this, the sodium gates close and potassium gates open. Positive potassium ions then flow out and the neuron becomes negatively.After this, the neuron becomes hyperpolarized. More positive potassium ions flow out. This ...
