A neuron is a type of nerve cell that is the fundamental element of the nervous system, and are comparable to most other cells in the body. The one main characteristic separates them from the others is their ability to broadcast information – these cells transmit signals along electrochemical gradients.
There are different types of neurons that work throughout our body. The most distinctive and are generally used in our daily activities are the sensory neurons, motor neurons, and interneurons.
Sensory neurons transport information from the sensory receptor cells all over the body to the human brain. These tell you about the temperature, pressure, movement, and pain you may experience in your environment. Motor neurons, on the other hand, send information from the brain to the muscle tissues, helping you both carry your groceries and digest your food as well. Interneurons transmit this information between them.
Neurons vs. Other Cells
Except for the red blood cells, all human cells, including neurons, feature a nucleus which stores genetic data. These cells have organelles that perform unique functions such as the mitochondria, endoplasmic reticulum, and the golgi bodies. Due to their constant biochemical reactions, the nucleus is enclosed in a protective membrane.
However, unlike other cells, neurons have hair-like extensions called dendrites that permit them to communicate throughout the body.
A neuron’s membrane is the only one of its kind used to deliver information to various cells throughout the body. With its axon and dendrites as its unique components, these are responsible for transferring and acquiring information from one cell to another.
These interactions that happen between cells, commonly referred to as synapses, occur when neurons discharge chemical messengers, also known as neurotransmitters, into these gaps to be able to successfully and effectively accomplish their role in the body.
Studies have also shown that learning, practice, novelty, exercise and many other activities help neurons develop, and that neurogenesis, the process of producing new nerve cells, does happen throughout life.
The Structure of a Neuron
There are three fundamental sections of a neuron: the cell body, the axon, and the dendrites.
In general, there is only one axon per neuron, but each of them can have more than one dendrite. Axons help transmit signals to its neighboring cell, and can vary in length – from micrometers to as far as reaching your toes. Dendrites are the branches lined with receptors designed to receive these signals from their surroundings.
Despite this, neurons can differ considerably in size, form, and features, based on their purpose and function. Certain neurons possess several dendritic branches, while some only have a handful of them to receive information.
Neural coding is a field of science focused on characterizing the connection between the stimulus, the group or individual neuronal reactions to it, and the corresponding electrical actions as a response. It is believed that neurons can easily encode both analog and digital information because of the theory that sensory data, among others, can be symbolized and classified through the wide range of its systems in the brain.
The neuron’s capacity to distribute signals quickly over substantial ranges is what makes it exceptional and unique among all the other cells in the body. They do this by producing characteristic, electrical pulses or voltage spikes that can move down through nerve fibers, called action potentials.
Sensory neurons alter their behaviors in the presence of an external stimulus such as touch, sight, taste, sound and smell by firing a series of action potentials in temporal sequences. Experts report that information about the stimulus is embedded in this impulse and is then passed to the brain. Despite the fact that action potentials vary in amplitude, shape and duration, they are usually similar with the stereotyped scenarios during neural coding tests – if a short period of an action potential is disregarded, a sequence can be defined by just a string of all-or-none point events in time. Essentially, the intensity and duration of the stimulus along with the threshold of the nerve will determine if a signal is transmitted.
With large-scale neural documenting and decoding technological innovations, scientists have started to unravel this mystery and have supplied us with the first glimpse into the actual neural code, our memory. It is created and stored in the hippocampus, a brain region considered to be an essential in memory development.
When you smell your favorite food, you are able to deliver signals to your brain to document a particular kind of smell and to determine and classify that it comes from a specific type of food.
The nerves in charge of sensing a stimulus and delivering details about it to the central nervous system are called afferent neurons.The receptors needed to identify the scent from your food are immediately turned on when bombarded with this sensory input, and delivers signals up to your brain by means of the afferent neurons. They then transmit the details about the chemicals to your brain allowing you to recognize the smell.
Similarly, when you see the food, light reaches your eye and activates sensors to deliver signals to your brain. Your brain gathers all these signals originating from the afferent system, in our example, both the eyes and the nose, to develop an image and smell, which will then simulate the taste associated to this specific food to your brain.
As soon as you saw the whole picture of your favorite food, both the smell and the sight, the nerves that send signals from to the central nervous system to the muscles are known as efferent neurons.
Once you made the decision to eat it, it was time for you to walk over to the table to get it. The brain delivered signals to the muscles informing them where to go and how fast to get there. Through the efferent neurons, the brain dispatched signals for your body to get going and to take a bite of the food. The easy way to remember this is Afferent Arrives at the brain, Efferent Exists the brain.
Interneurons and Association Neurons
The afferent and efferent neurons are typically not long enough to move from, for example, your big toe straight to your brain. Most afferent and sensory signals, which cross the spinal cord, are transferred to interneurons. The afferent neurons situated in the skin will utilize interneurons to convey its signals and alerts to the brain. An efferent neuron, on the other hand, will make use of an interneuron for its own signals.