Neural Communication: Synapses and Nerve Impulse Flow

Nervous Coordination and the Neuron System

Nervous coordination is carried out by the nervous system. This system is made up of nerve tissue whose cells, called neurons, are capable of transmitting information through nerve impulses.

Structure and Function of Neurons

Neurons are typically divided into three main parts:

• Cell Body (Soma): Contains the nucleus and other essential organelles.
• Dendrites: Short, branch-like projections that receive signals.
• Axon: A longer projection that transmits signals away from the cell body. It ends in a series of slender branches that widen slightly at the tip, called axon terminals.

In general, axons are protected by a white substance called myelin. The axons of various neurons sometimes group together to form nerve fibers, which then group together to form nerves.

Transmission of Nerve Impulses

Neurons are connected to each other at specialized junctions. The place where one neuron connects to another is called a synapse.

A nerve impulse is similar to an electrical current that is transmitted along the neuron's membrane and then onto other neurons through these synapses.

The neuron that transmits the message is called the transmitter neuron, and the neuron that receives the message is called the receptor neuron.

Chemical Synaptic Transmission

In the majority of synapses, the transmitter and receptor neurons aren't in physical contact. There is a small gap between them, known as the synaptic cleft. The message is transmitted across this gap by chemical substances called neurotransmitters, which are stored in the axon terminals.

In this type of chemical synapse, the nerve impulse is typically transmitted from the axon of the transmitter neuron to a dendrite, the cell body, or the axon of the receptor neuron.

Steps in Nerve Impulse Transmission Across a Synapse

Nerve impulse transmission across a synapse can be summarized as follows:

1. The nerve impulse, having been transmitted along the membrane of the transmitter neuron, reaches the end of its axon.
2. At the end of the axon, the arrival of the nerve impulse causes neurotransmitters to be released into the synaptic cleft.
3. Neurotransmitters bind to the membrane of the receptor neuron and generate a new nerve impulse.
4. The new nerve impulse is transmitted along the receptor neuron's membrane to its axon, where the whole process is repeated.