window.onload = function(){ alert("I had just recently designed a website as one of my science projects, and this was the end result d:") var label = document.getElementById("label"); var text = document.getElementById("text"); neuron(); } function neuron(){ label.innerHTML = "Neuron"; text.innerHTML = "

Types of Neurons

In our nervous system, communication is a vital part of fulfilling any task it must do, and neurons are what link everything together. Neurons are small, microscopic cells that transmit electrical and chemical signals between each other to trigger certain things to happen, allowing our brain to communicate with parts separate from it to do certain tasks, given the circumstance. Provided everything that the nervous system needs to do, there are several different types of neurons, all with their own specific purpose that work alongside each other. These different variations of the neuron include sensory neurons, a type of cell that converts reactions received from parts of the body (most commonly parts that influence our senses, such as our eyes or noses) into electrical signals from which it does something based on what is received; motor neuron cells, neurons that communicate with muscles in the body to do certain things, allowing for movement; and interneurons, a neuron that allows communication between both motor neurons and sensory neurons. Even with their diverse functionalities, they are all very important aspects of how the nervous system works and how it does what it does. Without neurons, it would be impossible for the nervous system to function the way it does and allow for organisms to do every incredible thing they are capable of accomplishing.

General Shape

Every neuron has its own distinct shape, but what links all the neurons together are the parts that make it up. The main part of the neuron, debatably the most important, is the soma or cell body. The soma is a round, spherical part of the neuron that holds most of the parts of the body of cell where all the nutrients that the neuron requires to stay alive are created.

One of these parts is the nucleus. The nucleus contains all the D.N.A. of the cell, deciding what it does and how it moves as its main function. Within the nucleus is the nucleolus, the part in the cell that creates most of the proteins via ribosomes and transfers R.N.A., a small part of the cell that aids in the creation of proteins, to the cytosol, where most of the proteins and organelles within the cell live. The Golgi apparatus is a thin, tube-like area in the soma. The look of it is very reminiscent of endoplasmic reticulum, given its thin and flexible body. The main purpose of the Golgi is to receive proteins from the rough endoplasmic reticulum and convert it into small packages known as vesicles. Outside of the soma is where the main purpose of the neuron is undergone, specifically where it transfers and receives electrical and chemical signals from other neurons. Dendrites are long branches that extend out of the soma, and are primarily used for receiving electrical signals from other neurons and transfering the signal throughout the rest of the receiving neuron. The axon is a long singular branch that extends out the other end of the soma and is used to carry electrical signals away from the cell body to the other end of the neuron, where the message will be transferred elsewhere. The axon is wrapped inside of the myelin sheath, an insulator that is used to drastically speed up the transmission of the signal to the receiving end. At the end of the axon is the axon terminal, which are long, branch-like parts. Their main purpose is to connect with the dendrites of other neurons via a synapse, where an electrical signal will be sent from the terminal to the dendrites, into the neuron receiving the signal.

Different Structures

The structure of neurons may vary from cell to cell, but it is often only separated into four distinct types. They are all based on the different parts of the neuron, how many of each part there are, and how they are all put together to make the cell. The first type, and often the most common to be seen within the brain, is the multipolar neuron. This type of neuron will often consist of a soma with an abundance of dendrites and only one axon. The multipolar neuron is typically found within the central nervous system, and given its large amount of dendrites, it will often be the cell that most prominently receives and transmits signals from one another, playing an important role in the nervous system.

The next type of neuron is the bipolar neuron, a type of neuron that takes up most of the sensory cells. Bipolar neurons generally have two axons protruding out both ends of the soma, where one axon leads to dendrites and the other leads to the axon terminal, with the soma having no dendrites coming out of it directly. The main role of a bipolar neuron is to transfer signals given off from your senses, and would be typically found in places that lead to the eyes, nose, ears, etc. Given their very specific use, bipolar neurons are quite rare within the body, and are generally only found in specific places in the nervous system. Unipolar neurons are a type of neuron where the soma connects only to the axon, with any dendrites found in the neuron connected to the axon near the axon terminal. Because the dendrites and axon terminal are located very close to each other, the electric signal sent into the neuron does not need to travel too far throughout the cell, therefore making a unipolar neuron electrically inactive. They are generally sensory neurons, usually found within the CNS, and will often be used to trigger impulses or reactions in the body. They are most commonly found in invertebrates, but also inhabit humans and most other organisms. The last type of neuron is the pseudounipolar neuron. This type of neuron is similar to the unipolar neuron in the way that no dendrites are directly connected to the soma, but rather through the axon. What differentiates pseudounipolar neurons with the unipolar neuron is that they typically have their soma isolated from any other parts of the neuron, only being connected by a small tube next to the rest of the cell. The tube that connects to the soma splits up into two branches, where one side generally focuses on communicating with the peripheral tissues and the other which connects with the spinal cord. These types of neurons are often created from a bipolar neuron, whose two sides fused together during development.

Communication Between Neurons

The entire nervous system of an organism is largely based around the communication of several parts from around the body, which is prominently done through the neurons. The communication between the cells is mostly done through chemical or electrical signals, in a process known as neurotransmission. When neurons communicate with each other, they will do so by connecting their dendrites and axon terminal together via a synapse, where the cell sending the message will send it out using an electrical signal, created as something known as an action potential from within the soma. When the signal is sent to the receiving neuron, it may trigger some receptors from within the dendrites, which pushes the neuron to release neurotransmitters. Neurotransmitters are chemicals released in the body, often used to communicate between neurons or from neurons to muscles. When the electrical signal is sent, there is a possibility of three different ways that the neurotransmitters released could affect any cells that receive them. The first way is excitatory, which will trigger the soma in the receiving neuron to create an action potential. The second is inhibitory, which does the opposite and will generally block any production of an action potential, stopping the neuron from being able to transmit signals. The last type is neuromodulation. When this is released, it will affect large amounts of neurons in an attempt to control the quantity of them."; } function glia(){ label.innerHTML = "Glial Cells"; text.innerHTML = "

What are Glial Cells?

Even though neurons play an important role in helping the nervous system function the way it does, it is not the only cell working on keeping it alive. The second type of cell, which has a population more than fifty times greater than the neurons, are the glia (also known as neuroglia or glial cells). Glia cells are typically non-neuronal cells, meaning that they do not conduct electricity from within them to communicate with each other, unlike neurons. They are often used to aid in the communication between neurons, rather than communicating themselves, and work to keep them out of harm. This allows the cells in your nervous system to live longer, allowing for an organism to live much longer lives. Had there been no glial cells, then all the neurons within the nervous system would starve and die, leaving glia to be very important aspects of an organism’s body.

Different Types of Glia

Glia cells appear mostly in the CNS and PNS and have several different things to do to keep the neurons and brain alive. This leads to there being several different kinds of glia, so that they amount of work needed to be done can be distributed across several cells. The type of cell that a glia can be is separated into two categories, macroglia and microglia, both of which having several different subtypes for different functions for both the CNS and PNS. In the CNS, the microglia act as the immune system of the brain and will try to identify any threats that may harm vital parts of the brain.

Some of the more common things that they will do is remove any dead neurons found within the organism, to avoid any unwanted problems that may occur as a result of the dead cell staying for too long. The next cell typically found in the Central Nervous System is known as astrocytes. This type of glia makes sure that all of the neurons are functioning properly and sending and receiving signals to each other with no issues. It does so by manipulating how much neurotransmitters are being released which prevents any issues that may occur from too much or too little neurotransmitters being sent out, keeping track of the number of ions in a general area, and providing the nutrients that neurons require to function to them. They get their name from their star-like shape, created from the abundance of processes protruding out all sides of the astrocyte. The second type of glia within the CNS is the ependymal cell. Ependymal glia cells make up the ependyma, acting as a barrier of protection for certain parts of the brain. These parts generally include the cerebrospinal fluid (often referred to as CSF) and the central canal of the spinal cord (a long area that runs all the way through the spinal cord). There has also been evidence to suggest that the ependymal cells play a role in regenerating neurons, although being unable to restore the cells fully. The third type of macroglia within the CNS is known as the oligodendrocyte. This type of glial cell is a cell that goes around to each neuron it may encounter and develop a myelin sheath for its axon. Without the use of the myelin, the signal required to travel across the neuron would take a substantially longer time to reach the axon terminal, making the use of the oligodendrocyte much more vital for fast communication. The last type of glia cell in the CNS is known as the radial cell, which is solely responsible for generating neurons, astrocytes, and oligodendrocytes. In the PNS, there are generally only three types of glial cells. The first type, schwann cells, are equivalent to the oligodendrocytes as they too develop myelin sheath for any neurons it may encounter. The next type, satellite cells, are similar, but not identical, to astrocytes. Their main purpose is to provide nutrients to the neurons, but they also act as an extra protective barrier for the soma of cells, as they will tend to wrap around the cell body to keep it out of harm. The last type of cell in the PNS is known as enteric cells. Although not too much is known about it as of now, there has been evidence to suggest that it does send and receive signals from nearby neurons and will also act similarly to astrocytes."; } function brain(){ label.innerHTML = "Brain"; var intro = "

Introduction to the Brain

The brain, given its extensive number of functions to manipulate an organism, is the most important aspect of the nervous system, and quite possibly of an entire organism. The brain is an organ which is roughly the size of both a person’s fists put together, located within the skull of an animal. Its main purpose is to control nearly everything that the organism does, from moving, eating, breathing, using the organism’s senses, etc. It is also prominently used for doing things that the organism itself cannot control, including emotions or the beating of a heart. This leads the brain to be an incredibly important part of allowing an organism to thrive and function the way they do, as without it, they would not be able to do anything. Given the large amount of functionality that the brain has, it also has a very complicated structure and complex inner workings, a lot of which we still do not understand. This leaves it to be an incredible mystery to us, which may take us generations to fully understand. Nevertheless, we have still been able to figure out the basics on how the brain functions, giving us a general understanding of how it may work. Our research as of now may lead to greater advancements and breakthroughs involving the brain, but time will only tell how long that may take."; var gaw = "

Grey & White Matter

Throughout the entire brain, it is comprised of two distinct parts – grey matter and white matter. Grey matter is any section of the brain that mostly contains the somas, dendrites, and axon terminals of neurons and any glial cells. It gets its name from the pink-grey tint that it gives off, and any section that is made up of grey matter is typically associated with muscle movement and perceiving any sensory signals. The white matter makes up parts of the brain that contain more axons, and acts as a connector between grey matter in order to shorten the time it take for information to be processed."; var cerebrum = "

Cerebrum

For everything that the brain does, it is all distributed across the entirety of the organ, with each section holding its own specific purpose on what it should accomplish. The human brain is split up into three major parts, the cerebrum, cerebellum, and brainstem. The cerebrum, or cerebral cortex, is located at the top of the brain and is the largest part out of the three.

This area is typically what controls all a human’s conscious actions, such as thinking, language, problem solving, and movement. Because of its large size in a human body, it separates us from any other organism alive, making us more intelligent and capable of figuring out creative ways of survival. The cerebrum is also split up into several smaller parts. The first four major parts are the lobes, which include the frontal lobe, temporal lobe, parietal lobe, and occipital lobe. The frontal lobe is the largest of the four and is located at the very front of the brain. This part of the cerebrum contains many neurons which are highly sensitive to the dopamine neurotransmitter, making it more associated with your personality and emotions. It also controls your problem solving, communication, short-term and long-term memory, and any conscious decisions you may need to make, which includes movement. The frontal lobe is split up into two different sides, the left and the right, where the right side of the lobe controls the left side of the body and vice versa. Underneath the frontal lobe and in the middle of the cerebrum is the temporal lobe. This lobe is used mainly for processing information provided by the body’s senses, although mostly associated with sound and sight. The temporal lobe allows for speech to be effectively processed when heard, allowing us to fully understand any information being told. This also allows us to formulate what we want to say and say it out loud to send the information to another person. The temporal lobe is also associated with processing visual information and recognizing things that we may see, working alongside the hippocampus and amygdala to create long-term visual memories based on what is received. Above the temporal lobe and in the middle of the top of the brain is the parietal lobe. This lobe is also very much associated with sensory information, similar to the temporal lobe, but functions more alongside the sense of touch and taste.

The parietal lobe is responsible for allowing for the feeling of touch in specific points in your body, which makes the feeling of when we touch something only concentrated on the part of our body that touched it, and distinguishing between the feeling of the touch of two or more objects, allowing us to feel objects individually rather than as one thing (this is often known as two-point discrimination). It also makes for everything around us feeling more distinguishable, including the ability to determine the size and shape of any objects you may see and figuring out how many there is of that one thing. Additionally, the parietal lobe is responsible for allowing you to recognize where you are in the space around you, which lets us know where all our body parts are even without the ability to see them. Lastly, this section has also been linked to the coordination of our movements. Without this lobe, movement would be near impossible as it would completely discard any coordination of your body and arms/legs, and it would be very difficult to determine where you may be in the specific area that you are in relative to other objects around you. The last major lobe in the cerebral cortex is the occipital lobe, which is the smallest of the four. The occipital lobe is located directly at the back of the brain, underneath the parietal lobe. This lobe is largely associated with vision, and is connected to the optic nerve, allowing for any light that enters the eyes to be directed towards it. The occipital lobe is capable of perceiving and recognizing colour and other objects we may see, and it is always receiving visual information from the eyes and processing it in roughly a few milliseconds. Without the occipital lobe, it would be near impossible to be able to see anything and even with the ability to see, we would be unable to recognize anything and remembering certain things. Alongside the four major lobes, the cerebrum is also divided further down into three subcortical parts within the lobes. The first part is known as the hippocampus, a small horseshoe-shaped part of the brain located in the temporal lobe. This small organ is the most important aspect of memories, specifically long-term memories, and plays a role on spatial recognition. When any new information is sent to the hippocampus, the neurons within it will decide whether to keep the information as a new short-term or long-term memory. If it is found to be unfit or unnecessary information, then it may just discard the information, letting you forget it entirely. How the neurons are capable of deciding whether or not to keep the information is very complicated, leaving us still to this day unable to understand how they do so.

Along with memories, the hippocampus is also responsible for allowing us to remember the places we have been through, making buildings easily traversed through after going around once. The second subcortical part in the cerebrum is known as the basal ganglia. This region is a group of several large nuclei, all located roughly in the center of the brain. The purpose of the basal ganglia is mainly to control eye movement and general muscle movement, which allows us to move parts of our bodies fluidly and fulfill any everyday actions. This part of the cerebrum has also been linked to the dopamine neurotransmitters, providing us with the feeling of pride and accomplishment, and it has also been associated with making decisions. The last of the three parts is the olfactory bulb, which is a section containing two small thin tubes in the front of the brain. The exact function of the olfactory bulb is still unknown to us, but some studies may suggest that it acts as a filter for the different senses, only allowing for certain sounds, smells, or feelings to affect us. Although not characterized as a subcortical part, the amygdala is also a major region in the brain and plays a role in determining who you are. The amygdala is a small portion of the temporal lobe, located right in front of the hippocampus. It is most prominently associated with emotions, depicting how you will act in certain situations, and provides you with your fight or flight sensation, which depicts how you should act in situations that may potentially be harmful or life-threatening. This section may also be the reason that we have certain fears or phobias, pushing us to avoid certain things that we believe could cause harm to us."; var cerebellum = "

Cerebellum

Even with the cerebrum’s vast use in allowing for our body to function, it is merely just a single part of the brain and cannot do everything that an organism needs to do. The second of the three major parts of the brain is known as the cerebellum. The cerebellum is a small, round shaped section located underneath the cerebrum and directly at the rear of the brain. Because it is directly connected to the spinal cord via the brain stem, the cerebellum is often associated with the senses, allowing for coordination, balance, smooth movement of the limbs, etc. Although it is a relatively old part of an organism’s brain, dating back thousands of years ago, even before the human species, the cerebellum is still a very useful area and contains roughly half of the brain’s neurons. Had there been any damage inflicted on the cerebellum, you would still be able to function as normal, with your general sense of sight, smell, etc. still somewhat in tact, but it may affect your ability to traverse your way around places and being able to make any precise movements with your limbs. Nonetheless, it is still a very important aspect of being an organism, and still holds a vital role in allowing humans to evolve to where we are. Looking at the anatomy of the cerebellum, it could also be divided into three major lobes within it.

The first lobe is generally referred to as the flocculonodular lobe (or vestibulocerebellum), which is an area located towards the front and center of the cerebellum and is made up from two major parts, the flocculus and the nodule. The hypothesis of what this area is generally used for is that it is responsible for learning some of the most basic skills that require muscle movement, including things like walking or sitting down. It has also been found to be associated with the movement of the head, allowing us to continuously see a smooth image, even during the movement of our head. The second major lobe within the cerebellum is known as the anterior lobe, which covers the majority of the cerebellum and is located around its edges. This section is mostly associated with the spinal cord, sending and receiving sensory information, and is capable of using the muscles in the body to push against gravity, making it responsible for posture. It also receives mostly all the proprioception signals sent from our muscles, allowing us to know subconsciously where we are in space without needing the ability to actually see our muscles. The last lobe is the posterior lobe, located in front and on top of the anterior and flocculonodular lobes, respectively. This lobe is the newest part of the cerebellum and is most often associated with the precision movement of our muscles, allowing for the ability of have fine motor skills."; var bstem = "

Brain Stem

Given the brain’s vital importance in being able to control limbs and muscles to allow for movement, it requires an efficient method of sending and receiving signals to and from specific sections of the body to achieve that. It does this via the brain stem, a section of the brain located directly underneath the cerebrum and cerebellum, and protrudes right through the center of the brain, allowing for signals to efficiently reach several sections. The brain stem is a thick and long tube that connects to the spinal cord, sending and receiving all signals, whether pain, sensations, or general movement of the limbs and muscles. Any information that needs to be sent to the brain is first received by the brain stem, which then sends it further to wherever it needs to go. Alongside transferring signals across the body into the brain, the brain stem also has a handful of several other functions for your body, including breathing, swallowing/digestion, and several involuntary actions such as your heart rate or blood pressure.

Additionally, to fulfill all its tasks, the brain stem is split up into three prominent parts - the midbrain, pons, and medulla. The midbrain is located in the center of the brain, connecting the brain stem with the cerebrum. It is a very important portion of our brain, given its extensive functionality, and is also split up into its own three smaller parts. The first part is known as the colliculi, which is a group of several large bunches of neurons, collectively creating the inferior colliculus and the superior colliculus. The superior colliculus is located right at the top of the brain stem and is most prominently in charge of receiving and recognizing visual information sent via the retinas. It is also in charge of processing several other types of information, all sent from different places in the body, mostly focusing on perceiving sensory signals. The inferior colliculus is located directly underneath the superior colliculus and will receive and perceive auditory information from the superior colliculus. It will most often work on recognizing different sounds and pitches and filtering out unnecessary sounds produced from chewing, breathing, etc. Similar to the superior colliculus, it will also receive other sensory signals and work on recognizing those but will focus more on the auditory information. Located underneath the colliculi is the tegmentum. This section runs through much of the brain stem and will often take charge in allowing for muscle movements and the control of any sensory system. This plays a very important role in being able to do everyday tasks, making it a vital part of the brain. The last of the three major parts of the midbrain is the cerebral peduncle, located towards the back of it. This section does little work on its own but will act as a connector between the brain stem and the cerebrum, aiding in the development of memories and movement. The second of the two parts that form the brain stem is the pons, a section located underneath the midbrain. This area typically acts as the bridge for signals between several parts of the brain and body, allowing for information to be processed via different parts of the brain. Although still not very certain of it, scientists have found evidence suggesting that the pons may also be associated with the formation of dreams initiated in REM and may also be the section responsible as the cause of sleep paralysis. The last section of the brain, the medulla, is the section most prominently associated with involuntary actions, such as the beating of the heart, breathing, sneezing, digestion, and vomiting. It is the absolute most important part of the brain, as it would be near impossible to live without it and damaging it in any way could cause significant damage to your body and brain as you would not be able to pump blood throughout your veins and constantly replenish yourself of oxygen."; var tmem = "

Different Types of Memories

One of the most incredible things that our brains are capable of accomplishing for us is the ability to formulate memories from things that occur in our everyday lives, which may last either a very limited duration of time as a memory or a permanent one, sticking with you until the day you pass. Provided the complexity and importance of the formation and storage of memories, it is still a very unknown process for the most part on how it works, but we have been able to understand some key things about it that could help us with understanding more in the future. In our minds, there are two major memory types that memories can be stored as. Short-term memory is the first of the two types and is often associated with any memories that can only be remembered for a short period of time, lasting approximately 15 to 30 seconds. Within that time frame, the memory that had just been created would be completely discarded of, making it close to impossible to recall the same memory following that period. The second way that a memory could be stored would be as long-term memory, allowing the newly created memory linger to either a few minutes or for the rest of your life.

Given how many things can be stored as long-term memory, any memory created may fall into one of two categories, implicit or explicit memory. Implicit memory is any type of memory that may be created without trying to make it a memory and can be recalled without the need to think of it too much. This may include muscle memory (e.g. riding a bicycle, walking, or driving a car), which is typically known as a subcategory of implicit memory referred to as procedural memory, or associated/recognizing words or objects because of previous knowledge of something related to it, which is typically known as priming memory. In short, recalling implicit memories are generally done unconsciously and automatically by the brain, allowing for fulfilling simple and repetitive tasks, such as walking or reading, to be done much easier and more efficiently. The second subcategory of long-term memories is known as declarative or explicit memories. This type of memory is created consciously, meaning that you are aware during the formation of the memory that it will become something you will remember later, and it usually consists of events or information that you have experienced or learned about and as a result had remembered it. As a declarative memory, the memory created may either be a semantic or episodic memory. A semantic is memory that stores knowledge that may have been taught through school or just everyday life. The knowledge learned is typically facts or information on a specific thing and can either be created via repetition of the information or from the memory merely forming from hearing it a limited number of times. Episodic memories are the memories of events or occurrences throughout your life, which have made a large enough impact that they have converted to long-term memories. Information of the event that you may remember could include the date that it had occurred, the location of it, the people that had been there, or your general feeling(s) at the time during the event."; var fmem = "

Formation of Memories

As the brain storing two types of memories is a very well-known fact that most neuroscientists understand, the formation of the memories are what make it the mystery that it still is to this day. Our current theory on how memories are created is based around synaptic plasticity. Synaptic plasticity is the idea that synapses may be able to manipulate the strength of themselves when transmitting signals from one neuron to another, which varies the synaptic strength, or the level of strength that the synapse allows itself to send the signal across. A weaker synaptic strength results in less of the signal to be transferred across to the receiving neurons and vice versa. Additionally, how long the change stays for the synaptic plasticity is based on whether it is a short-term synaptic plasticity, making the change only linger for roughly a few milliseconds, or long-term plasticity, making the change in plasticity stay for a very large amount of time, possibly even leaving it permanent. For synaptic strength to remain high, the constant reactivation of the soma to create an action potential is needed, meaning that two neurons would need to repetitively be required to send signals between each other for the synaptic strength to stay strong. Even though the way this ties in with the formation and recalling of memories is still a theory, it is a good candidate for how it may potentially work and so far, it is the only idea that seems to fit. When a new memory is formed, the structure and quantity of neurons and proteins vary from before the memory had been created and a group of neurons are called to store the information of the memory (this process is still very much unknown to us, and the decision of whether the memory will be stored as long-term or short-term, if it should be stored at all, is also a mystery). Generally, for short-term memories, the synaptic strength of the synapses within the group of neurons holding the information is quite weak, putting the group of neurons in a position where they could easily fall apart and lose the information, making the memory forgotten. For long-term memories, the synaptic strength is fairly high within the group of neurons that carry the memory, allowing for it to linger around for a longer period of time, possibly even indefinitely. Additionally, how it is possible to create long-term memories via repetition of information may be possible because constantly repeating a certain thing may strengthen the synaptic strength between the neurons, allowing for the group of neurons storing the memory to stay around longer. Even though memory is stored all throughout the brain, it is most often stored and formed in the hippocampus, making that a very vital part in memories. Whether this theory is true or false (and there has been some evidence against it), memories are quite possibly the absolute most fascinating aspect of the brain, and even though it is still unknown to us, the formation is a very complex and interesting process and greatly adds to the enigma which is the brain."; text.innerHTML = intro + gaw + cerebrum + cerebellum + bstem + tmem + fmem; } function nsystem(){ label.innerHTML = "Nervous System
"; text.innerHTML = "

Introduction to the Nervous System

For nearly every living being that had walked the face of the earth, their ability of movement was what defined them as the organism that they were, as this ability allowed them to fulfill any task required. Without the capability to move, no species would be able to do anything they do today, humanity included. It allows us to do anything that we need to do, such as walking to different places or picking something up, which in turn makes it a vital part of being a living organism. How humans, and nearly every other species that make up the animal kingdom, are able to move the way we do is all possible because of several systems within our bodies, but the one that most prominently allows for our limbs to be moved is the nervous system. This system is a complex part of our bodies that contains billions, even trillions, of smaller cells, nerves, and other parts to keep it functioning the way it does. It connects the entirety of our body together, making us all one being that constantly communicates with several other parts within ourselves, allowing for our everyday actions to be as possible as the parts that allow for the actions. The nervous system greatly defines who we are as a person, as our actions are typically used to judge our personality, and all our emotions are created within it. Even though the brain is a very important part of being alive, it would never have become what it is today without our nervous system, and as it connects our entire body together, no other system within ourselves would have the ability to do what they do without it. For this, we are merely all that we are today because of our nervous system and we would never have been the same without it.

Central Nervous System

The nervous system runs all across our body, reaching nearly every part. To account for this, it is divided into two separate sections, known as the Central Nervous System (CNS) and Peripheral Nervous System (PNS). The CNS is the main part of the nervous system that controls all our actions, affecting and manipulating parts in the PNS to react to whatever the body is needed to do, either from reflex or just general body movement indicated to occur from the organism itself.

The CNS consists of two main parts, the brain and spinal cord, which work together to fulfill any actions required to happen. The spinal cord connects to the bottom of the brain via the brain stem, located directly underneath the cerebellum and cerebrum, and runs down the majority of the back of the human body. It is surrounded by a type of bone named vertebrae which protects it and allows for the spinal cord to stay firmly in place where it needs to, preventing possible damage to it. The spinal cord is typically made up from an abundance of neurons, all grouping together to create grey and white matter, similar to the brain. The main purpose of the spine is to carry signals sent from the muscles to the brain and create nerves to be distributed throughout the body. It does this in five different sections within the spinal cord, which all split into several different smaller segments of spinal nerves (a type of nerve that can transmit any type of signal, whether sensory, motor, or autonomic, making it a type of nerve known as a mixed nerve), totalling up to 31 pairs within the sections. The first section of the spinal cord, located directly at the top, is made up of eight cervical segments (labeled C1-C8). This section is most often associated with the neck, given its position in the human body, and controls most parts within its proximity (controlling most of the top portion of the body). Beneath the cervical segments are the thoracic segments, made up from 12 thoracic nerves (labeled either Th1-Th12 or D1-D12). These segments are located towards the mid section of the spinal cord and are closely associated with the chest, abdomen, and hands/fingers. Underneath the thoracic segments are the lumbar segments (labeled L1-L5), containing five different sections of lumbar nerves.

Each section supplies different and varying amounts of muscles to regions near the hips and knees. Below the lumbar segments is the sacral region (labeled S1-S5), located at the pelvic area. This area controls most of the sections connected to the pelvis and the legs. Lastly, the coccygeal region is located directly at the bottom of the spinal cord and only consists of one pair of spinal nerves. Although this area does not control any limbs, it is connected to the skin around the tailbone (also known as the coccyx). All these segments are attached to parts in the body, sometimes several different parts, and effect each section in certain ways. This may be providing a route for transmission from muscles to the brain, supplying muscles or other resources to different parts, or delivering signals from the brain to wherever it is needed. Alongside that, these sections are also responsible for any involuntary reflexes that may occur in a situation where we could be in danger or we think we are (e.g. jumping or flinching when getting scared or pulling away from something that had hurt us). Whether natural reflexes or reflexes that you had learned from practice, the spinal cord tries whatever it can to keep you out of harm, making decisions to move specific muscles or limbs nearly in an instant, making it a powerful and valuable part of our bodies. Had any injuries inflicted damage on the spinal cord, it could easily result in serious and possibly permanent damage to your body. This may include paralysis of certain parts in your body, the loss of sensations, and difficulty in doing everyday things such as walking, going to the washroom routinely, and breathing. Serious damage could very much be life-threatening or may greatly limit your movements and general feelings drastically for the rest of your life. Whatever the case, the spinal cord is a very important aspect of the nervous system as it connects everything together and allows for the vital aspect of communication between parts of our bodies to be a possibility.

Peripheral Nervous System

Throughout the entire body of an organism are a massive number of nerves and ganglia (a large cluster of nerve cells. These nerves are all what allow for movement of the different parts of our limbs and for our senses to affect us, connecting nearly everywhere in our bodies to the CNS to allow for this. These large numbers of nerves/ganglia are what make up the Peripheral Nervous System (PNS), which creates the second portion of the entirety of the nervous system. For what the PNS does, it is divided further down into two separate sections that both work on different things. The somatic nervous system (SNS) is the first of the two subsystems, associated with the connections between the muscles/sensory organs and the brain. It primarily consists of motor and sensory neurons to allow for movement of the muscles and feelings or sensations, making it more responsible for voluntary actions. This means that most of what the SNS is responsible of doing it mostly dependant on the host of the body, as they control everything that it does, with an exception on the senses. The SNS is also capable of recognizing and reacting to something that had affected either the surface or insides of our bodies, which is done via a subsystem of the SNS known as the somatosensory system, which allows for us to recognize whenever something had touched us in some way. This provides us with feelings of pain, pressure, movement, etc., making for an important aspect for letting us perceive where we are in space and what the objects around us are.

Alongside the somatic nervous system is the autonomic nervous system (ANS), a system most prominently responsible for the connections between our internal organs and the brain. It provides them with what they need to continue to work and controls most of the involuntary actions associated with the organs. This may include the beating of the heart, digestion, urination/defecation, blood pressure, and breathing. To do all this, it is divided further down into two smaller subsystems to control different things associated with the organs. The first system, the sympathetic system, is largely associated with the amygdala in the sense that when the amygdala sends out a signal for the fight or flight response, the sympathetic system will reply by activating the actual feeling of danger, pushing for the organism to do something related to the situation. During the response, it will raise your heart beat and blood pressure, and may also release some chemicals into your body, providing you with the feeling of stress and worry during that time. The section part of the autonomic nervous system is the parasympathetic nervous system. This system will do the opposite of the sympathetic system as it will control the body while at a rest state, lowering the blood pressure and heart rate and making you feel more calm and relaxed. It controls what is known as “rest and digest”, where it processes the food and waste within the body, resulting in the process of the digestion of food and defecation/urination. It also influences your feelings of sexual arousal and the production of any liquid in your body, including tears and saliva. To lower your stress and heart rate, the parasympathetic system will release chemicals within your body to slow you down and make you feel calmer, undoing any of the affects that the sympathetic system had inflicted, had you recently been in a fight or flight situation. These two systems work together in unison to allow for us to be ready in certain situations, lowering the chances of getting caught off guard or being unable to defend ourselves because of us doing something else. Furthermore, they allow for all our internal organs to do what they do, enabling for every other system in our bodies to function and providing us with everything necessary to survive. Without the autonomic system, nothing within our bodies would be able to work, resulting in life to be near impossible to thrive and evolve. "; } function diseases(){ label.innerHTML = "Mental Illnesses & Diseases"; var introduction = "

Introduction to Mental Disorders/Diseases

For every person on this Earth, their brain and nervous system are far from perfect. Several things within our bodies could go wrong in one way or another, which may lead to problems that could affect our brain and nervous system, leading to either mental illnesses or diseases. These problems affect everyone in different ways, often leading us to deal with it in our own ways. Whether this may be taking medication, talking to someone, or dealing with it in a more specific way, every problem has a different way to be approached and handled, and there is most often a way to get through it. One of the biggest problems that involve that, however, is that people may not get diagnosed and properly treated based on their situation, which may be the result from personal fears or the general feeling of being unable to do so, leaving them to try to deal with it on their own. This could make the problem for them worse, which could lead to the damage inflicted from the issue worse than it needs to be, putting them in a state of desperation and loneliness, possibly leading to actions that they may regret doing. Whatever the case, anyone is susceptible to contracting a problem, and whether it may linger around for years or only come as one or several reoccurring episodes, it can impact our lives in many ways. Even though it may not seem like it, mental disorders affect the best of us, and how we choose to deal with them will depict how much we will allow for it to control us. Letting it take control could lead to feelings of loneliness or helplessness, and although it may feel as if you have no control over yourself, anyone would be capable of getting the help they need to get past those thoughts. We are all merely just organisms fighting the same battle with our minds and thoughts, and even for those who have it the worst, there will always be a possibility of recuperation. Even in the worst of times, we can always find a path of recovery, and even if it may not seem as if there is today, there is always the possibility of it opening in the future."; var als = "

Motor Neuron Disease

Motor Neuron Disease (also known as ALS or Lou Gehrig’s disease) is a type of disease that primarily affects the entirety of the nervous system, and more specifically, the motor neurons within them. Motor neurons are a type of neuron that connect to different parts of the body to allow for movement. Without them, the ability to control and move your limbs would be very difficult, as they play a vital role in being able to do so. ALS works in the way that it will go through each motor neuron in your body and gradually weaken them to the point that they cannot do any work and perish.

This classifies Lou Gehrig’s disease as something known as a neurodegenerative disorder, or a disorder that will progressively kill off most, if not all, of your neurons. Provided that the body is unable to fully regenerate and recreate neurons, the disease, if continuing long enough, will cause permanent damage to the body, most often resulting in the paralysis of most or all parts of your body. Even though we understand how the disease works its way throughout your body, we are still unclear on why or how it comes into effect within your body. For now, all that is known about the disease is that it does become inherited throughout generations, making the children of those with ALS at a higher risk of contracting it than those with parents without the disease. There has also been evidence to suggest that while at an older age, you become exposed to a greater chance of getting it, which may also show that it may not always be linked to inheritance. Because of our current uncertainty on the cause, there is currently no working treatment on how to prevent the illness, but rather only methods to slow down the effects. Some of these methods include different types of therapy, medication, and using certain tools for replacing functions in our bodies that may have become incapable of fulfilling its task. Even though these methods may not always work and cannot fully prevent the progression of the disease, they have been shown to make the speed at which the effects impact you to lessen, providing a longer life span and maximising the amount of time you may still be able to use your muscles. However, ALS is known to be a fatal disease, leaving the sufferer with merely only five to ten years before the disease may take them. Although there have been cases where people have been capable of living past the estimate of time that they had left, such as with Stephen Hawking, but these cases are typically quite rare, leaving for the majority of the cases to leave the sufferer with a short amount of time. Nevertheless, research is being done in fields where it may provide us with a cure or treatment that will near eliminate all symptoms for the disease, and even though we have not been able of finding anything as of yet, research on stem cells have provided evidence that may lead to the treatment of ALS, but time will only tell if that may be the case."; var depression = "

Depression

Depression is a mental illness that directly affects the brain, manipulating one’s thoughts and feelings towards themselves and everything around them. It may leave the sufferer with feelings of loneliness, helplessness, and weakness that could lessen the amount of happiness they may feel regularly, limiting it to nearly no feelings at all. This may push the person to constantly feel down and in a state of thought where it would push them to believe in their own uselessness in the world, leaving the sufferer in a terrible position, difficult to escape from. Unfortunately, if this goes untreated, it could lead to self harm and, in the most extreme cases, the point where the person may try to end their own life. Although this disorder is horrible and can drastically affect one’s life, most often for the worse, we have been able to figure out the reason behind the illness and how it may affect our brain on a microscopic level. The exact cause of depression may be linked to several causes, but the most prominent and important one is the chemical imbalance between the neurons within the brain. Within our bodies, we all contain a specific type of neurotransmitters known as monoamine neurotransmitters. Some of these chemicals, specifically those such as dopamine, serotonin, and norepinephrine, are often linked to feelings of pleasure, general mood and behaviour, and regulating blood pressure and heart rate, respectively.

In general, most of monoamine neurotransmitters affect how you feel, providing you with feelings of happiness and trust towards other things. For those affected by depression, their bodies will generally be unable to produce and transfer these neurotransmitters between the neurons. This will limit the feelings that the sufferer may feel in their everyday life, resulting in feelings of sadness because of the loss of the neurotransmitters that allow for happiness or pride towards themselves. Additionally, depression has also been observed as an illness that can be inherited, putting those with parents who had suffered from it at a higher risk of contracting it themselves. Even though we still cannot fully understand the effects and causes of the illness, we have been able to gather enough understanding of it to create a treatment that, most of the time, will help alleviate the effects of depression. Some of these treatments include taking certain drugs, most often reuptake inhibitors which try to provide and allow for the transmission of certain neurotransmitters, and therapy. Although though they may not be able to work with everyone, these methods have helped thousands, even millions, of people suffering from the illness. However, only a small fraction of people get properly treated for, so although we have a treatment, we still require a better way of distributing it to everyone who needs it. This could be very difficult, but more research is being done in the field, allowing for hope in the future of a better way to helping people out with getting over depression."; var anxiety = "

Anxiety

Anxiety is a mental disorder, more common than others, that affects roughly 10% of the population of Canada each year. It is a disorder characterized by the excessive and frequent feelings of nervousness or fear in situations that would typically not induce the same feelings towards others (e.g. social interactions, speeches/performances towards an audience, or completing tasks/assignments).

There are several different types of anxiety disorders that you may experience, with some kinds including social anxiety, a type of anxiety that induces nervousness in people while in social situations, often because of the fear of being judged by others; panic disorder, generalized by the frequent occurrences of panic attacks within someone; and generalized anxiety disorder (GAD), which may create fear within someone as a result of several different things, rather than certain things in specific. In the minds of those dealing with anxiety, they generally experience their feelings the way they do because of the inability for their brains to be able to process certain situations correctly, misinterpreting them for situations that may be harmful towards us. Panic disorder, although still difficult to understand by scientists, is thought to occur because of amygdala sending out feelings of panic towards other parts of the brain. In most cases of panic disorder, this signal is often overlooked by the other parts, often not stopped or transmitted elsewhere, which will result in our conscious selves receiving the signal and providing us with the panic attack. The same can be said about social anxiety and GAD, where simple situations may cause the amygdala to send out feelings of panic, alongside the decrease in serotonin levels within our bodies. The lack of serotonin may often lead to additional feelings of sadness or loneliness, which in turn may also result in those suffering from anxiety to also experience depression. As of now, our current methods of professionally dealing with anxiety include therapy and different drugs, including anti-depressants."; var alzheimers = "

Alzheimer's Disease

Alzheimer’s disease is a common disease, generally affecting those among the age of 65. Similar to ALS, Alzheimer’s is a neurodegenerative disease, meaning that it typically targets and kills the neurons within your brain and body. As a result, it makes any damage inflicted onto one suffering from it irreversible, making it a very dangerous disease. Furthermore, it is also a progressive disease as it will worsen the longer one may have it. As a result, the symptoms one may experience will come in seven different stages throughout having the disease. Throughout the stages, the problems occurred typically affect the sufferer’s memory and cognitive ability, weakening their ability to remember certain things from a short while ago or from their past and impacting their capability of doing tasks, such as solving math problems or doing their taxes. At its worst, someone suffering from Alzheimer’s disease will be unable to recognize themselves and where they are, remember anything (destroying one’s long-term and short-term memory), and even moving their muscles. As for the past several years there has been a great amount of research concerning the disease, scientists have been able to figure out the basics of how the brain is affected by Alzheimer’s. Given how greatly our bodies are affected by the disease, both mentally and physically, several things occur in the body of one suffering from Alzheimer’s. The first problem is the lack of certain neurotransmitters within ourselves. Some of these chemicals include acetylcholine, which aids in the production and storage of memories; glutamate, a neurotransmitter that allows for the communication between neurons, and serotonin. The second most prominent cause of the occurrence of Alzheimer’s disease is the β amyloid (also know as beta amyloid). β amyloid is known as the leading cause of the production of amyloid plaques, doing so by grouping together into large groups. These plaques will bunch up in the synapses of neurons trying to communicate, which limits the ability for them to send signals between each other. This can be very toxic towards the cells, resulting in their death, slowing down and limiting the ability of some of the basic functions within your mind and body. Provided that Alzheimer’s is typically associated with the loss of the ability to use your memory, this may occur most often in parts of the brain responsible for performing that task such as the hippocampus.

The last most prominent cause of the disease is neurofibrillary tangles within the neurons. These tangles are a very important aspect of understanding Alzheimer’s disease, as they can greatly impact important functions that the neurons require to survive. Neurofibrillary tangles are created by an abundance of the τ protein, a type of protein used to stabilize the long tubes within the cytoplasm of cells known as microtubules. In a healthy neuron, these tubes are used to transport resources towards the axon, fulfilling a similar role as the endoplasmic reticulum. Although the τ proteins are a vital part for the microtubules to be created and function properly, they can also destroy them. In the neurons of an Alzheimer’s patient, the protein will form up into several large groups of disformed fibers around the microtubules, damaging the tubes and killing them. Because of this, no nutrients would be able to travel to the axon, leaving the cell to be near purposelessness and will merely be left to starve. Neurofibrillary tangles are most often found in the cerebral cortex (the outer layer of the cerebrum) and the hippocampus, playing a role in the loss of memory. Even though we understand how the disease affects the brain, we are still unable to understand how we contract the disease and therefore and to stop it. There are no current treatments or cures for Alzheimer’s, with only a few methods to limit the affects of the disease, leaving those suffering from it with a shorter life span, often only being left with 3-8 years after diagnoses, depending on the age. Given its slow and progressive symptoms, it is a terrible disease, affecting even those not affected with it, and has caused the suffering of millions of people worldwide. Nonetheless, there are several research facilities and organizations that primarily focus on the research of Alzheimer’s disease, trying to provide us with a better understanding of it for the future. Additionally, because of this research, we may be able to start working on some sort of a treatment for the disease in the near future, allowing for millions of lives to be spared from the terrible impacts of it."; var autism = "

Autism Spectrum Disorder

Provided the large spectrum of mental disorders and diseases, there are several common illnesses, leaving a high probability for you to have encountered someone suffering from them. Some of the widespread problems will generally fall under what is known as the autism spectrum, a group of similar disorders that will likely affect people in near identical ways at varying severities. Underneath the spectrum are two prominent illnesses – autistic disorder and Asperger syndrome. These two problems typically affect the sufferer’s social skills, only being capable of speaking until a certain age (which varies depending on the disorder they have), and will often provide them with specific habits that may come off as strange to others. These habits generally include the constant requirement of repetition, needing for most things in their lives to follow a certain schedule or routine, and the obsession over one specific thing. Those suffering from either of the two disorders may also have varying amounts of trouble learning new things, having it be more difficult for those with autistic disorder. Nonetheless, any problem under autistic spectrum disorder is never fatal and those with any of the disorders will often live average and normal lives, provided they had been properly cared and educated for as a child. Furthermore, it has also been seen that those with the conditions may have greater attention to detail, allowing for them to be excellent in certain job positions. The neuroscience of the disorders is generally influenced by abnormalities in specific sections of the brain, including the cerebellum, brain stem, and several smaller parts within the cerebrum. Some of the odd characteristics of these parts of the brain generally include varying sizes of the parts, with the cerebellum having to be observed as slightly smaller than usual and parts of the cerebrum to be noticeably larger, and a difference in size and density of the groups of neurons. From the research, it seems that the neurons would tend to be slightly smaller and condense closer with other neurons, making for most of the cells within certain parts of the brain to be in very close proximity with each other. Another issue that may influence whether one has autism spectrum disorder is the number of neurotransmitters within the body. GABA (gamma(γ)-aminobutyric acid) is a type of neurotransmitter that is generally used to calm down the body by slowing down the process at which neurons will function. With those that have autism spectrum disorder, it has been seen that they will generally have a smaller number of GABA, and although scientists are still unsure why or how this influences autism disorders, it seems to play an important role in understanding the cause of it. Even though the cause of autism spectrum disorder is still very much unknown to us, there is active research in universities such as the MIT on autism, providing hope for more of an understanding of the disorders in the future."; var epilepsy = "

Epilespy

Epilepsy is a common mental disorder directly associated with the brain and CNS. It is generally classified as a disorder that causes reoccurring episodes of seizers, or a period where one may lose entire control over certain or all parts of their body and functions. Seizures could last from either thirty seconds to, in the worst cases, approximately five minutes. They may come in different severities, depending on the situation and person experiencing them. Some seizures could only leave the person with a few jerks of movement in some parts of their body, such as the arms or legs, while others may tend to leave them completely unconscious and out of control over themselves, resulting in the sudden and involuntary movement of all parts of their body. Although they may not always be fatal, those with seizures that would make them unconscious and lose control of their body would be at risk of biting their tongues, which, even though could not result in them choking, could lead to immense damage and pain. Although the exact cause and affect seizures have on the brain is still unknown, there has been some research to suggest certain things.

One main thing that occurs during a seizure is the chaotic and spontaneous transmission of electrical signals all across the brain or between specific parts, depending on the type of seizure created. The cause of this has been linked to several different things, but the most prominent include glial cells, GABA, and the transmission between the neurons before the seizure. Glial cells and GABA are typically used to regulate and inhibit the activity within the brain and body, calming and slowing down the communication, allowing for everything to function properly. A possibility on why seizures may occur could be that the glia and GABA would be incapable of fulfilling their task, leaving the neurons to be left at their own devices. This may be what leads to the chaotic electrical signals that spread around the brain during a seizure, as the neurons may potentially be unable to control the communication themselves. Another possible cause would be something potentially blocking and disallowing the ability for neurons to communicate via one another, which, although still not very understood, could lead to the seizures to occur. As those with epilepsy suffer from reoccurring episodes of the seizures, it has been thought that it may be because of the possible misconnection between nerves within the brain, leaving for further issues to continuously occur and putting them at a higher risk of contracting seizures. Whatever the case, further research is still required to be able to develop a working treatment, as the current methods of dealing with it still have several flaws. Our current knowledge is still insufficient which leaves for lots of gaps in our understanding of epilepsy. If we are able to close these gaps, it will allow for our current methods of dealing with the disorder to be drastically improved."; text.innerHTML = introduction + als + depression + anxiety + alzheimers + autism + epilepsy; }

Science Project