Where is the multipolar neuron located

Myelin is produced by glial cells. Along these types of axons, there are periodic gaps in the myelin sheath. It is important to note that a single neuron does not act alone. Neuronal communication depends on the connections that neurons make with one another as well as with other cells, such as muscle cells. Dendrites from a single neuron may receive synaptic contact from many other neurons.

For example, dendrites from a Purkinje cell in the cerebellum are thought to receive contact from as many as , other neurons.

There are different types of neurons; the functional role of a given neuron is intimately dependent on its structure. There is an amazing diversity of neuron shapes and sizes found in different parts of the nervous system and across species. While there are many defined neuron cell subtypes, neurons are broadly divided into four basic types: unipolar, bipolar, multipolar, and pseudounipolar. Unipolar neurons have only one structure that extends away from the soma. These neurons are not found in vertebrates, but are found in insects where they stimulate muscles or glands.

A bipolar neuron has one axon and one dendrite extending from the soma. An example of a bipolar neuron is a retinal bipolar cell, which receives signals from photoreceptor cells that are sensitive to light and transmits these signals to ganglion cells that carry the signal to the brain. Multipolar neurons are the most common type of neuron. Each multipolar neuron contains one axon and multiple dendrites. Multipolar neurons can be found in the central nervous system brain and spinal cord.

The Purkinje cell, a multipolar neuron in the cerebellum, has many branching dendrites, but only one axon. Pseudounipolar cells share characteristics with both unipolar and bipolar cells. It contains a brain, ventral nerve cord, and ganglia clusters of connected neurons.

These ganglia can control movements and behaviors without input from the brain. Octopi may have the most complicated of invertebrate nervous systems. They have neurons that are organized in specialized lobes and eyes that are structurally similar to vertebrate species. Various nervous systems : a In cnidarians, nerve cells form a decentralized nerve net. Mollusks, such as squid and e octopi, which must hunt to survive, have complex brains containing millions of neurons.

In f vertebrates, the brain and spinal cord comprise the central nervous system, while neurons extending into the rest of the body comprise the peripheral nervous system. Compared to invertebrates, vertebrate nervous systems are more complex, centralized, and specialized. While there is great diversity among different vertebrate nervous systems, they all share a basic structure: a CNS and a PNS.

One interesting difference between the nervous systems of invertebrates and vertebrates is that the nerve cords of many invertebrates are located ventrally near the abdomen , whereas the vertebrate spinal cords are located dorsally near the back. The nervous system is made up of neurons, specialized cells that can receive and transmit chemical or electrical signals, and glia, cells that provide support functions for the neurons by playing an information processing role that is complementary to neurons.

A neuron can be compared to an electrical wire: it transmits a signal from one place to another. Glia can be compared to the workers at the electric company who make sure wires go to the right places, maintain the wires, and take down wires that are broken.

Although glial cells support neurons, recent evidence suggests they also assume some of the signaling functions of neurons. Four major types of neurons transmit signals through the body via specialized structures such as dendrites, axons, and synapses. The nervous system of the common laboratory fly, Drosophila melanogaster , contains around , neurons, the same number as a lobster.

This number compares to 75 million in the mouse and million in the octopus. A human brain contains around 86 billion neurons. Despite these very different numbers, the nervous systems of these animals control many of the same behaviors, from basic reflexes to more complicated behaviors such as finding food and courting mates.

The ability of neurons to communicate with each other, as well as with other types of cells, underlies all of these behaviors. Most neurons share the same cellular components. But neurons are also highly specialized: different types of neurons have different sizes and shapes that relate to their functional roles. Each neuron has a cell body or soma that contains a nucleus, smooth and rough endoplasmic reticulum, Golgi apparatus, mitochondria, and other cellular components.

Neurons also contain unique structures, relative to most cells, which are required for receiving and sending the electrical signals that make neuronal communication possible. Dendrites are tree-like structures that extend away from the cell body to receive messages from other neurons at specialized junctions called synapses. While some neurons have no dendrites, other types of neurons have multiple dendrites. Dendrites can have small protrusions called dendritic spines, which further increase surface area for possible synaptic connections.

Cellular structure of neurons : Neurons contain organelles common to many other cells, such as a nucleus and mitochondria.

They also have more specialized structures, including dendrites and axons. Once a signal is received by the dendrite, it then travels passively to the cell body. The cell body contains a specialized structure, the axon hillock, that integrates signals from multiple synapses and serves as a junction between the cell body and an axon: a tube-like structure that propagates the integrated signal to specialized endings called axon terminals. These terminals, in turn, synapse on other neurons, muscles, or target organs.

Chemicals released at axon terminals allow signals to be communicated to these other cells. Neurons usually have one or two axons, but some neurons, like amacrine cells in the retina, do not contain any axons.

Some axons are covered with myelin, which acts as an insulator to minimize dissipation of the electrical signal as it travels down the axon, greatly increasing the speed on conduction. This insulation is important as the axon from a human motor neuron can be as long as a meter: from the base of the spine to the toes. The myelin sheath is not actually part of the neuron. Myelin is produced by glial cells. Along these types of axons, there are periodic gaps in the myelin sheath.

It is important to note that a single neuron does not act alone. Neuronal communication depends on the connections that neurons make with one another as well as with other cells, such as muscle cells.

Dendrites from a single neuron may receive synaptic contact from many other neurons. Arrows indicate the direction of excitation flow along the neuron, from input to output. Multipolar neurons: Search for multipolar neurons in glass slide 48 in your Histology slide box, cerebellar cortex of pig Golgi stain. Note: Three layers are recognized in the cerebellar cortex superficial gray matter of the cerebellum : 1 an outer molecular layer composed of few cells and many nonmyelinated fibers, 2 an intermediate layer comprised of flask-like cell bodies called Purkinje cells , which are multipolar neurons , and 3 an inner granular layer composed of tightly-packed cells and fibers.

Question: Why is the Purkinje cell considered a multipolar neuron? All multipolar neurons have two characteristics: -- more than two processes emanate from the cell body, and -- the cell body receives synaptic input just like the dendrites. Neurons Three major categories of neurons are recognized: Bipolar neurons are relatively rare. The arrow points to an axon of a Purkinje neuron. At middle of the slide, cell bodies of three Purkinje cells neurons are visible as black, rounded, profiles.

Cell processes, termed dendrites , extend superficially from the cell body into the molecular layer.