Because the axon hillock represents the beginning of the axon, it is also referred to as the initial segment. Within the axon hillock, the cytoplasm changes to a solution of limited components called axoplasm. This is a tapering of the cell body toward the axon fiber. Where the axon emerges from the cell body, there is a special region referred to as the axon hillock. Figure 12.8 shows the relationship of these parts to one another.įigure 12.8 Parts of a Neuron The major parts of the neuron are labeled on a multipolar neuron from the CNS. This gives the neuron a polarity-meaning that information flows in this one direction. Information flows through a neuron from the dendrites, across the cell body, and down the axon. The dendrites are usually highly branched processes, providing locations for other neurons to communicate with the cell body. The other processes of the neuron are dendrites, which receive information from other neurons at specialized areas of contact called synapses. It is the axon that propagates the nerve impulse, which is communicated to one or more cells. That single axon can branch repeatedly to communicate with many target cells. Neurons are usually described as having one, and only one, axon-a fiber that emerges from the cell body and projects to target cells. But what makes neurons special is that they have many extensions of their cell membranes, which are generally referred to as processes. The cell body contains the nucleus and most of the major organelles. Parts of a NeuronĪs you learned in the first section, the main part of a neuron is the cell body, which is also known as the soma (soma = “body”). The three-dimensional shape of these cells makes the immense numbers of connections within the nervous system possible. An important part of the function of neurons is in their structure, or shape. They are responsible for the electrical signals that communicate information about sensations, and that produce movements in response to those stimuli, along with inducing thought processes within the brain. Neurons are the cells considered to be the basis of nervous tissue. Neurons are important, but without glial support they would not be able to perform their function. Ongoing research pursues an expanded role that glial cells might play in signaling, but neurons are still considered the basis of this function. Glial cells, or glia, are known to play a supporting role for nervous tissue. They are electrically active and release chemical signals to target cells. They are responsible for the computation and communication that the nervous system provides. Neurons are the primary type of cell that most anyone associates with the nervous system. Nervous tissue is composed of two types of cells, neurons and glial cells. List the glial cells of the PNS and describe their function.List the glial cells of the CNS and describe their function.Identify the different types of neurons on the basis of polarity.Describe the basic structure of a neuron.
By the end of this section, you will be able to:
0 kommentar(er)
