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Giulia: This is a documentary or the nervous system. We hope that after watching this presentation you will understand this complex system a little bit better

Jason: I think, therefore I am. This famous scientific quote from Rene Descartes refers to one of several extremely important things the nervous system allows us to do. Although we, as the dominant species on the planet, consider thought to be the most important given it allows us to act and make decisions beyond our impulse, and allows us an excuse to not be classified as pure animals, we will be focusing on the less recognized activities the nervous system allows us to carry out, and how the nervous system functions for our well-being. These primary functions this system carries out for our decisions and actions are receiving information, responding to information, and maintaining homeostasis. The first function, receiving information, simply refers to our acknowledgment of our surroundings. We can see and feel the area around us. We recognize pain, and recognize pleasure.

Giulia:This system also checks how our body is operating, by, for example, keeping track of the levels of glucose in our body. The second function is responding to information received. Any change or signal that makes our body respond is called a stimulus. Some responses caused by stimuli can be controlled, but many, such as our heart rate, are involuntary and cannot be resisted. To keep a stable internal condition in our body, or homeostasis, our nervous system directs our being to respond correctly to stimuli and information it receives. If we're hungry, we are inclined to eat by the nervous system. This is a way the nervous system maintains homeostasis.

Jason: The nervous system is made up neurons. Neurons respond to what is around you. They are affected by something inside or outside of your body.There are many types of neurons: sensory neurons respond to touch, sound, and light. Motor neurons receive signals from the brain and spinal cord and cause muscle contractions.Inter-neurons connect neurons to other neurons in the brain and the spinal cord.

Giulia:The information that a neuron carries is called a nerve impulse. To be able to carry the message or information, a neuron has to have a special structure. The neuron has a large cell body that contains the nucleus, threadlike extensions called dendrites and an axon. The dendrites carry nerve impulses toward the neuron's cell body. The axon carries impulses away from the cell body. Nerve impulses begin in the dendrites, move toward the cell body and then down toward the axon. A neuron may have many dendrites but it only has one axon. An axon however has many tips so it can transmit several nerve impulses at a time.

Jason: It continues toward the cell body, through the axon, and to the axon tip. The impulse travels through the entire neuron as electrical and chemical signals. These impulses begin when receptors in different sensory organs pick up stimuli. They, in turn, cause nerve impulses in sensory neurons. Then the impulse travels to inter-neurons in the brain. The brain then interprets the signal and tells you how to react. Glia are the supportive nervous tissue that aid the neurons.

Giulia: Now we move on to the divisions of the nervous system. The nervous system is clearly divided into two categories. There is the central nervous system, and the peripheral nervous system. The central nervous system is the control center of the body. It includes the brain and spinal cord. All the information is brought to your brain. The spinal cord is a thick column of nervous tissue that links the brain to most of the nerves in the peripheral nervous system. The brain contains approximately 100 billion neurons, all of which are inter-neurons.Three layers of connective tissue cover the brain. The space between the middle layer and the innermost layer is filled with a watery fluid. There are three main parts of the brain that receive and respond to information. These are, the cerebrum, the cerebellum and the brain stem. The cerebrum is the largest of them. It interprets input from the senses, controls movement and carries out complex mental process like learning and remembering.

Jason: The cerebrum is divided into two parts. The left and right half.The right half sends impulses to the skeletal muscles on the left side of your body, and the left half controls the right side of your body. In addition each half of the cerebrum controls slightly different mental activities. The right half is associated with artistic and creative thinking, and ability. Giulia: And the left side is associated with logical thinking.

Jason: The peripheral nervous system, the other division, branches out from the central nervous system and connects it to the rest of the body. The nerves in this system are either somatic or autonomic. The somatic nerves control voluntary actions. The autonomic nerves control involuntary actions.

Giulia: Thank you for watching this documentary.

Jason: We hope you learned something new about the nervous system.