The Complex Nervous System Biology Essay

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Nerves are perhaps the most fascinating and complex part of our bodies. They give us the ability to understand and interact with the world around us and create the thoughts and store the memories that make us human. Without them we would be inanimate chunks of meat.

Nerves are made out of neurons, which exist throughout our entire bodies, constantly sending messages to our brain. The neurons in our skin send messages to the brain about the texture and feelings we experience, as well as the temperature, and pain if we are injured. The specialized neurons in our taste buds can differentiate between the chemicals in our mouths and can send messages to the brain which can interpret these as flavours and taste. In our ears the neurons can pick up the vibrations in the air and relate them as being sound. The nerves in our eyes bring the information from the rod and cone cells to the brain, which gives us vision. The equilibriums which are organs filled with fluid use nerves to sense the waves created by our movement to give us sense of balance.

Nerves are made of billions of neurons, each one with the ability to send a signal. One or two neurons firing would have no meaning, but millions of neurons firing in unison can send a complex message or thought. All of these signals from the neurons come together and run along a nerve into the spinal cord. The spinal cord is basically the neuron freeway that all the nerves in our bodies converge to bring all the signals to the brain, which is itself a huge mass of neurons making sense of all the signals it receives.

The dendrites are long string-like structures coming off the cell body. If they sense the right force, chemical or energy, they send a signal to the nucleus, telling it to send a synapse. The synapse is an electrical charge which is sent down the axon to the axon terminal. The myelin sheath protects the axon and greatly speeds up the signal. When the charge hits the terminal it causes some specialized organelles to create a chemical which jumps the gap to the next neuron, which when stimulated by the chemical, sends a signal of its own (see Figure 2).

The electrical charges that cause these synapses are created by the action potential inside the neuron. The action potential is when the cell builds a negative and then releases it down the axon. To build up this negative charge the cell brings in negative potassium and sodium ions through the cell membrane via sodium potassium gates and pumps. The gates and pumps are specialized proteins designed to bring the molecules inside the cell (see Figure 3).

As you can see, the sodium potassium pump brings in two potassium ions and pumps out three sodium. To help the sodium potassium pumps fill the cell with potassium, specialized proteins known as the sodium potassium gates bring a certain amount of potassium into the cell as well. The sodium potassium gates also bring in a certain amount of potassium, aiding the sodium potassium pumps in their job. Once the cell has a charge of -70 millivolts the cell releases the charge down the axon via ion channels. Next, the cell briefly releases all of its potassium outside the cell and lets in some sodium through the sodium potassium gates. The combined effects of releasing the ions down the axon and letting out more of the ions out through the membrane gives the cell a charge of +40 millivolts. This whole process is known as the action potential.

(see Figure 4).

Figure 4


This process of firing synapses can occur approximately a thousand times per second. This makes a very small part of your body capable of sending billions of signals per second as a very complex message.

All of the nerves are connected together, passing on their signals to the next nerves. This vast network eventually channels into nerves which are tightly packed strings of neurons. The nerves then come from all the parts of the body and connect into the spinal cord.

The spinal cord is about 45cm long in men and 43cm in women, stretching from the base of your skull down to your tailbone, which is part of your spine as well.

The spine is comprised of tightly-packed nerves and support cells feeding the neurons, known as grey matter. This is all encased in the vertebral column which is made up of thirty-three vertebrae with gel pads in-between to keep the vertebrae from rubbing. The spinal column is fairly flexible except for the sacral tip. The spine is divided into five regions: the cervical, thoracic, lumbar, pelvic and sacral (see Figure 5).

Figure 5


As you can see, the upper regions of the spine control the upper parts of the body and the lower regions control the lower half. However, in the event that the spine is severed, all the regions below it are disabled as well. For example, if the spinal cord is severed at T12 you would not be able to use your legs, would have no sexual function and be incontinent. For this reason the higher up on your spine there is damaged the greater the damage will be. If you break C3, you lose control of your diaphragm which results in no longer being able to breathe which results in death unless the individual is immediately put on a ventilator.

Multiple Sclerosis is a disease where your immune system attacks the myelin sheath, damaging the neurons' ability to communicate with each other. This results in loss of muscle control. M.S. usually strikes suddenly little forewarning, crippling the victim almost instantly. This can be very dangerous because the victim can fall and not be able to protect themselves when they land. After the initial strike there is a two to ten hour recovery where the victim regains some muscle control before another attack occurs. There are generally two to four attacks and after each one the victim regains slightly less muscle. The lasting effects of the attack vary quite a bit; some victims can't walk after the attacks, others only experience a slight feeling of weakness. It generally just depends on how badly the myelin sheath is damaged. The myelin sheath is often able to able to repair itself to some degree but full recovery rarely happens.

Scientists still don't really know what causes the immune system to attack the myelin sheath but they have found that smoking raises the risk by three times. Lack of Vitamin D and stress also appear to play a big role. There is no proven cure; however there are some drugs that stop future attacks from occurring. Some people think herbal remedies are the answer. Medicinal cannabis and ingesting hookworm eggs are surprisingly two of the most popular natural remedies but there is little evidence to support that they help at all. However, a healthy diet with lots of omega 3 fatty acids, antioxidants, and Vitamin D has been shown to aid the rehabilitation process.

Autism is a problem with nerve synapses where the synapses don't connect properly to the brain, causing information to be misconceived by the brain. The

symptoms of this include: strange behaviour including stereotypy which involves repetitive movements and noises; compulsive behaviour which involves arranging or organizing objects in stacks or lines; resistance to change or new ideas; daily rituals such as eating the same food or wearing the same clothes on certain days; focus in only a few interests such as a toy or television program; and self injury from repetitive movements such as skin picking, eye poking, hand biting, and head banging.

Unlike M.S., autism is hereditary and there is no way to prevent it from occurring. People with autism are usually born with it although rarely children with no autistic symptoms will develop autism though their childhood. There is absolutely no cure for autism and there is little hope of finding one considering it is written into the very DNA of the person with it.

Autistic people have difficulty developing language and social skills so they often have difficulty functioning in society. However, there are quite a few autistic people who have battled with their illness and have gone on to be quite successful in life. In fact there is a strong argument which suggests that autistics' alternative view of reality provides can provide beneficial new ideas, art, and thoughts.

... Research demonstrates that autistic traits are distributed into the non-autistic population; some people have more of them, some have fewer. History suggests that many individuals whom we would today diagnose as autistic - some severely so - contributed profoundly to our art, our math, our science, and our literature. (F)

It is well believed some of the most brilliant humans that ever lived were autistic. Hans Christian Andersen, Beethoven, Edison, Henry Ford, Kafka, Mozart, Nietzsche, Tesla, Alan Turning, Jane Austenm, Emily Dickenson, Einstein, Thomas Jefferson, Michelangelo, Newton, Mark Twain, Henry David Thoreau, and Nostradamus were are all believed to be autistic."If by some magic, autism had been eradicated from the face of the earth, then men would be socializing in front of a wood fire at the entrance of a cave" (F).

The thoughts and views of autistic people can definitely seem strange and bizarre to us but there is no denying that behind the social and language barriers there is brilliance that ordinary people simply do not have and if that brilliance can be exposed can enlighten us with brilliant new ideas.

In conclusion, neurons are the foundation of what makes us human; all of our knowledge, memories and emotions are created and stored by them. But is the greater amount of neurons we have what separates us from animals? Our limited knowledge suggests neurons are what give us comprehensive information on the world around us giving us the ability to create new things and be able to advance rather than have one stationary lifestyle of just surviving. Some suggest the essence of life is as simple as neurons firing thousands of times: "I don't think there's anything unique about human intelligence. All the neurons in the brain that make up perceptions and emotions operate in a binary fashion. We can someday replicate that on a machine. Earthly life is carbon based and computers are" (F).

Scientists say they have figured out why we have emotions, and that they understand how love and compassion are created. They suggest there is no moral right or wrong if all our choices are based on neurons firing and memories and hormones being released. If that is so people, do not make choices but rather everything we do is predefined by our hormones and what our neurons tell us.

Regardless of this explanation, many scientists are still stumped by how we are so much more creative and socially complex than any animal. Having a larger brain just simply doesn't make enough of a difference. Chimpanzees have roughly the same size brain as us. It seems that humans have a completely different software controlling them or rather they don`t have a software at all. Humans have an incomparable ability to make decisions that can only be explained by religion or presuming there is yet some mystery still to discover in the biology of human that sets us apart from animals.