C2.2.1 Neurons as cells within the nervous system that carry electrical impulses Notes

Neurons Transmit Electrical Signals to Enable Rapid Communication in the Nervous System

1. Neurons are specialized cells of the nervous system responsible for transmitting electrical signals throughout the body.
2. They are uniquely structured to receive, process, and send information rapidly, allowing the body to react and adapt to internal and external stimuli.
3. Neural signaling involves the transmission of electrical impulses, which are propagated along the specialized structures of the neuron.

The Structure of a Neuron: A Cell Designed for Communication

1. A neuron is uniquely structured to transmit information efficiently.
2. It consists of three main parts: the cell body, dendrites, and an axon.

The Cell Body Is The Control Center

The cell body is the neuron's core, containing the nucleus and cytoplasm.

Dendrites Are The Signal Receivers

1. Dendrites are short, branched fibers that extend from the cell body.
2. They act like antennas, receiving signals from other neurons or sensory receptors.
3. These signals are then transmitted to the cell body for processing.

The Axon Is The Signal Transmitter

1. The axon is a single, elongated fibe rthat carries electrical impulses away from the cell body.
2. Axons can vary in length, from a few millimeters to over a meter in some cases, such as those connecting the spinal cord to the toes.

How Electrical Impulses Travel Along Nerve Fibres

Neurons communicate through electrical impulses called action potentials. These impulses travel along the nerve fibers, including dendrites and the axon.

The Role of the Axon

1. The axon is the primary pathway for transmitting electrical signals over long distances.
2. It is often covered by a myelin sheath, a fatty layer that insulates the axon and speeds up impulse transmission.

The Role of Dendrites

1. Dendrites play a crucial role in receiving signals from other neurons.
2. These signals are usually in the form of neurotransmitters, chemical messengers released at synapses, the junctions between neurons.
3. When neurotransmitters bind to receptors on the dendrites, they trigger electrical changes that can initiate an action potential.

The Journey of an Electrical Impulse

Let’s break down how an electrical impulse travels along a neuron:

1. Signal Reception: Dendrites receive a signal, causing a change in the electrical charge across the neuron's membrane.
2. Action Potential Generation: If the signal is strong enough, it triggers an action potential at the axon hillock, the junction between the cell body and the axon.
3. Impulse Propagation: The action potential travels down the axon as a wave of electrical activity.
4. Signal Transmission: When the impulse reaches the end of the axon, it triggers the release of neurotransmitters, which carry the signal to the next neuron or an effector cell (such as a muscle).

Neurons Are Essential for Communication

1. Neurons are the foundation of the nervous system, enabling rapid communication between different parts of the body.
2. They allow you to:
   1. Sense your environment (e.g., detecting heat or cold).
   2. Process information (e.g., interpreting visual or auditory signals).
   3. Respond to stimuli (e.g., moving your hand away from a hot surface).