Going through my registration process into college, I came in contact with a lot of people. Diverse in attitudes, dressing and comportment, all in a room waiting to be interviewed. Even though our differences lies in the way we dressed, it was more than that- it's better described as skin-deep.
The differences we have among us as humans with different races and religion can be traced down to the upbringing we had; these include the teachings we have been exposed to. It boils down to the mind and its moldings. So the almost one thousand student in the room competing for admission to study BSc. Physiology have their difference at a structural level from the brain.
The brain is the seat of our consciousness and personality. Every lessons we learn, every good memories, jokes, lyrics of musics, our like and dislikes are all having their seats in the brain. Let me break this to you- we fall in love with our brains (A topic for another time).
You might have wondered what the brain looks like in reality and how it performs its function; how a soft squishy structure is able to controls all physiological activities occurring in the body and also extends to defining our abilities and talents- Why we do the things we do, why we react to circumstances in a manner differently from the way others do.
I know we all know what the brain looks like, but just the thought of this small, delicate substance controlling the activities of the body is a wonder to behold. This is actually the brain of a chimp and it is similar to that of a human being but for some important functions.
This image is authored by Gaetan Lee, source wikipedia. com license CC-SA-BY 2.0
The function of the whole brain can be studied at a more smaller level- cellular level. The neurons are the principal cells that up the brain, the spinal cord and the nerves which innervates different tissues of the body. The network of structures responsible for controlling the body with the use of electrical signals is called the nervous system- The nervous system in different organisms are developed and adapted differently. Humans being regarded as higher animals owe this ability to the way the brain is structured and complexed.
The brain and spinal cord make up the central nervous system while the nerves which allow it to communicate with other tissues make up the peripheral nervous system. The Nervous system is one of the two systems that regulates all other system.
As we all know that cells are the basic and functional unit of life, this also applies to the Nervous system. So it would be proper to first understand the type of cells in the system, their structures and functions. Anatomists would call it Neurocytology, which is the simply the study of the cellular component of the the nervous system.
The cell in this system are called Neurocytes which is divided into Neurons and Neuroglia.
The cells of the nervous system are just like other cells of the body. They perform the typical function of cells for the nervous system.There are many types of neurons in the body, but for the sake of this article we'll just be talking about one to generally explain their structure and function.
Image Author: Bruce Blaus --- Source: Wikimedia.com --- Licence: CC-BY 3.0
The neuron/nerve cell are the basic cells of the Nervous system concerned with the receiving, processing and transmission of impulses (signals) in the body.
It has an axon projecting out of its soma (Body) and a lot of branches known as dendrites.
Dendrites are the collectors of the signals from the surface of the body, inner most parts of the body and anywhere impulses are generated.
Their main function is to receive and process information. If the stimulus is strong enough, then something called an action potential is formed which then makes us aware of a feeling or sensation.
Axons make up most of the fibers of the nervous system
These are more longer than dendrites and they maintain a uniform diameter throughout their length. Like I said earlier, it arises from the cell body at a region known as the axonal hillock where the famous action potentials are formed.
Axons most of the time are covered with myelin sheet which is a special insulating substance that makes the travel of action potential down the axon much faster. One of the main reasons why we can feel a sensation in nano seconds. Towards the end they separate into several branches known as the axonal terminal where the axons make targeted communications with targeted cells.
Synapes
The site at which information is carried or transmitted from a first neuron (pre synaptic neuron) to a target neuron (post synaptic neuron).
They are called Neuromuscular junctions when they occur between the neurons and skeletal muscle and Neuro effector junctions when they occur between neurons and smooth muscle.
At most synapses, information is usually transmitted my chemical messengers medically known as Neurotransmitters. Triggers from the action potential generated usually causes the release of these chemicals.
The chemicals then bind to the membrane of the post synaptic neuron thereby conveying the information/impulse.
Classification
Based on the role and functions of neurons in the nervous system, they are classified into;
Sensory Neurons
They acquire information or impulses from the body and send the information to the Central nervous System (Brain) to be processed.Motor neurons
They convey processed information from the brain to the body, muscles, organs and glands. Their axons innervates the these organs that the impulses were generated.Inter-Neurons
They are only found in the Central Nervous System and they receive information from sensory and inter neurons and transmit them to motor and inter neurons.
Neurons actually intertwine with each other for the transmission of impulses (information) to occur.
NEUROGLIA
Also known as supporting cells of the Nervous system. There are four (4) types in the Central Nervous System and two (2) in the Peripheral Nervous System.
- Astrocytes
- Microglia
- Oligodendrocytes
- Ependymal cells
And in the Peripheral we have the;
- Schwann cells and
- Satellite cells
Astrocytes
This types of supporting cell is the most numerous and is found both in the brain and the spinal cord. It's main function is to protect the blood-brain barrier. It also regulates communication between presynaptic and postsynaptic neurons at the synapse .
Microglia
They act as the phagocytotic scavengers removing neuronal debris from the Nervous system.
Oligodendrocytes
These are the supporting cells that produce myelin that makes communication fast within the Central Nervous System.
Ependymal cells
These cells have cilia (a kind of hair-like structures) that aids the circulation of cerbrospinal fluid (a fluid that acts as cushion to the brain and spinal cord) within the ventricles of the brain and spinal cord.
Schwann Cells
This type of neuroglia is found in the Peripheral Nervous System and they perform similar functions (Production of myelin sheath around the axons on neurocytes) with the Oligodendrocytes in the Central Nervous System.
Satellite Cells
Their main function is to cover the bodies of neurons in the ganglia of the Peripheral Nervous System.
So there you have it
The cellular components of the brain explained and now you at least know the things that happen when you feel an impulse or sensation. This article is just a preamble to fully understand the brain and the spinal cord.
To understand the nervous system is no easy fit and more information are being gathered.
Comments will be warmly welcomed.
