Final answer:
The structure of a motor neuron includes a cell body with a nucleus, dendrites for receiving impulses, and a long axon for sending impulses. The axon is often covered by a myelin sheath to speed up signal transmission, with occasional gaps called Nodes of Ranvier to facilitate rapid impulse conduction.
Step-by-step explanation:
Structure of a Motor Neuron
Motor neurons are specialized cells that carry nerve impulses from the central nervous system to muscles and glands. Their structure is well adapted to this function. A motor neuron is composed of the following parts:
- Cell Body: The cell body contains the nucleus and other organelles, and is the site of most of the neuron's metabolic activity.
- Dendrites: These are thin, branched processes extending from the cell body that receive nerve impulses from other neurons.
- Axon: This is a long projection that transmits nerve impulses away from the cell body towards other neurons or effector cells (muscles or glands). The axon may be wrapped in a myelin sheath, which accelerates the impulse conduction.
- Nodes of Ranvier: Gaps in the myelin sheath that allow for the rapid transmission of nerve impulses.
- Axon Terminals: The branched ends of the axon where the neuron forms synapses with other cells.
The axon hillock is the part of the neuron where the axon emerges from the cell body, and it plays a critical role in initiating nerve impulses. Myelin sheaths are created by Schwann cells, which not only provide insulation but also aid in the repair and regeneration of axons. Motor neurons are an example of multipolar neurons, which possess several dendrites and a single axon.