Neurons are the cells in our brain that process information and allow us to think, see, hear, taste, touch, and smell. Our neurons make up about 20% of the human brain — a pretty small portion when you consider everything else that’s in there. But what those little guys lack in quantity they more than make up for in quality. Neural networks are amazing structures that allow our brains to process information from the senses, store it as long-term memory, and recall it when necessary.
They are so fascinating because they are the smallest unit of the brain that can function on its own outside of a larger structure like the cerebrospinal fluid or blood vessels (source). Neurons are scattered throughout the brain, but clusters of them appear most prominently in three regions:
What Is A Neuron ?
A neuron is a specialized cell that makes up the nervous system. The human brain contains approximately 100 billion neurons, each with many tiny branches that extend from one end to the other. When we think about neurons, we usually think about the length and diameter of the cells. But a neuron’s shape is not what makes it so powerful. It is the way that it is structured internally. Neurons are incredibly complex, but they are also incredibly simple.
They have a cell body, an axon, and dendrites. The cell body is the main part of the neuron. It contains the nucleus, mitochondria, the endoplasmic reticulum, and the other organelles that make up a typical cell. The axon is the part of the neuron that’s shaped like a wire. It’s responsible for sending messages to other cells. The dendrites are the slender fibers that branch out from the cell body. They are the neuron’s receivers.
Types Of Neurons
There are many different types of neurons in the human brain. Some are specialized to receive information, while others specialize in sending it. The types of neurons are as follows:
- Sensory neurons: These neurons receive information from the senses. - Motor neurons: These neurons send information to muscles.
- Interneurons: These neurons make up the “middlemen” of the brain, receiving information from sensory and motor neurons and then passing it on to other neurons as needed.
- Association neurons: These neurons receive information from other neurons and then pass it on to other association neurons.
- Memory neurons: These neurons receive information from other neurons and then pass it on to the part of the brain responsible for storing long-term memory.
How Do Neurons Communicate ?
Neurons do not actually touch each other. Instead, there is a tiny gap between each nerve cell called a synapse. When we are young and our brains are developing, these synapses are highly malleable. The strength of the signal that travels across a synapse is determined by the number of neurotransmitters released into the synapse. When a neuron is ready to pass on a signal, it releases a neurotransmitter into the synapse. The neurotransmitter crosses the synapse and binds to receptors on the next neuron, passing along the signal.
In order for the signal to cross the synapse, a neuron must be activated. The neuron is able to activate itself by secreting an enzyme called an enzyme that breaks down the cell’s energy source, ATP. Once the neuron has broken down the ATP, it becomes unstable and is unable to receive new energy. This sends the neuron into a state of hyper activation, and it releases the neurotransmitter in a sudden burst.
Synapses And Synaptic Conduction
Synapses are where neurons communicate with each other. When a neuron has enough ATP, it can secrete a neurotransmitter. This neurotransmitter crosses the synapse and binds to receptors on the next neuron. This binding triggers an electrical signal inside the second neuron that travels along the length of the neuron. This electrical signal is what allows us to think, feel, and remember. When the electrical signal reaches the end of the neuron, it can either be sent back out through the synapses or be stored as long-term memory in the cell nucleus.
This storage process is called transcription. When you are young, your neurons are incredibly plastic. This means that the amount of time it takes for the electrical signal to travel from one neuron to the next is relatively short. As you get older, however, your neurons become more rigid. This is because the plasticity of your neurons decreases as you age, meaning that it takes longer for the electrical signals to travel from neuron to neuron.
Exocytosis: How Neurons Communicate Through Neurotransmitters
Neurons communicate with each other through the release of neurotransmitters. When a neuron receives a signal, it is ready to pass that signal on to the next neuron. In order to do so, it has to break down ATP and release one of these neurotransmitters. This process is called exocytosis. In order to do it, the neuron has to break down and re-form the neurotransmitter inside of the synaptic vesicles. This can be a very complicated process. Depending on the neurotransmitter, it can take anywhere from milliseconds to hours for the synaptic vesicles to break down, form the neurotransmitter, and travel to the synaptic membrane.
The human brain is an incredibly complex and amazing organ. But the complexity of our brains can sometimes lead to misunderstandings. There are many ways of looking at the human brain and neurons. Neurons are a very important part of our brains. They carry signals from one cell to another, allowing us to think and feel. These signals travel along axons, which are the long wires that neurons have. The strength of the signal that travels along an axon is determined by the number of neurotransmitters that are released into the synapse.
When the neuron is ready to pass on a signal, it releases a neurotransmitter into the synapse. The neurotransmitter crosses the synapse and binds to receptors on the next neuron, passing along the signal. When a neuron is activated, it breaks down ATP and releases one of these neurotransmitters. This neurotransmitter crosses the synapse and binds to receptors on the next neuron. This binding triggers an electrical signal inside the second neuron that travels along the length of the axon and is either sent back out through the synapses or stored as long-term memory in the cell nucleus.