What is a nerve cell, and how does it work?
Nerve cells, or neurons, are specialised cells that play a critical role in our bodies by transmitting information as electrical signals.
These cells are vital in connecting different body parts to the central nervous system (CNS), including the brain and spinal cord.
Neurons have unique structures that help them perform this function effectively, allowing them to carry and relay signals rapidly across long distances in the body.
Structure of a nerve cell
Neurons have a distinct structure that supports their ability to transmit electrical impulses. They consist of:
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Dendrites and dendrons: Small, branching extensions that receive signals from other neurons and pass them toward the cell body.
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Cell body: The central part of the neuron contains the nucleus, cytoplasm, and cell membrane. The nucleus controls the cell’s activities.
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Axon: A long fibre extending from the cell body, transmitting signals away from the neuron. Axons can be up to 3 feet long, depending on the neuron's location.
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Myelin sheath: A fatty layer that wraps around the axon, insulating it to speed up the transmission of electrical impulses. The myelin sheath ensures that the signals are conducted efficiently along the axon.
How nerve cells transmit electrical impulses
Nerve cells function by responding to stimuli—changes in the environment detected by special cells called receptors. When a stimulus occurs, neurons transmit electrical impulses from one part of the body to another.
This process begins with the sensory neurons, which detect external stimuli like heat or pressure. They send electrical signals to the CNS through their axons. Inside the CNS, relay neurons (or interneurons) connect sensory neurons to the brain or spinal cord. The information is then relayed back through motor neurons, which carry the impulse to effectors like muscles or glands, producing a response.
Types of neurons
There are three main types of neurons, each with a specific function:
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Sensory neurons: Detect stimuli and send signals to the CNS.
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Relay neurons: Connect sensory neurons with motor neurons within the CNS.
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Motor neurons: Transmit signals from the CNS to muscles or glands, causing a response.
Synaptic transmission: How neurons communicate
Neurons communicate with each other at junctions called synapses. When an electrical impulse reaches the end of a neuron (axon terminal), it triggers the release of chemicals called neurotransmitters.
These chemicals cross the synapse and bind to receptors on the neighbouring neuron, passing on the signal. This process ensures that information is relayed throughout the body, enabling responses to stimuli like light, heat, or sound.
Conclusion
Nerve cells are essential for relaying electrical impulses throughout the body. Their unique structure, including dendrites, axons, and the myelin sheath, supports their ability to transmit signals quickly and efficiently.
Neurons communicate through synapses to process and respond to stimuli, making them critical for all bodily functions, from simple reflexes to complex behaviours.
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