{ Human Nervous System 1/14/2015

Introduction The Human Nervous System is comprised of two sections: The Central Nervous System and the Peripheral Nervous System. The combination of the efforts of both of these systems allow us to analyze and sense changes inside or outside of our bodies, while simultaneously allowing us to respond and react to these changes.

Human Nervous System The Human Nervous System can be compared to the nucleus in a eukaryotic cell. It controls processes within the body, responds to internal and external situations, and manages the body. Overall, the human nervous system is composed of the brain, the spinal cord, spinal nerves, cranial nerves, and sensory organs and receptors.

Central Nervous System The Central Nervous System is located in the center of the body and receives information from sensory organs from the Peripheral Nervous System and analyze/interprets the information. In response, the Central Nervous System also reacts with signals and movements through the Peripheral Nervous System, inadvertently or purposefully. This system, in addition to the Peripheral Nervous System, is made of specialized nerve cells called neurons.

Parts of the Central Nervous System Spinal Cord: located in the center of the back of the torso, the spinal cord is surrounded by nerves from the Peripheral Nerve System. Brain : located in the back and the upper front of the head, the brain contains billions of neurons that transmit, carry, and contain information that control response.

Parts of the Brain The brain itself is made of four main parts: the cerebrum, the cerebellum, the diencephalon, and the brain stem. The cerebrum contains 85 percent of the brain’s matter. These four parts are connected to senses and bodily movements.

Neurons Neurons are specialized cells that are specifically shaped to service the nervous system. They can receive, respond, send/transmit, and/or analyze information that is being sensed. Interneurons are specifically found in the CNS and respond to information that is sent their way. Afferent Neurons and Efferent Neurons are found in the Peripheral Nervous System. These neurons send automatic impulses to the CNS

Neurons Neurons are built like a normal eukaryotic cell, with a nucleus in the center. A series of “branches” grow outwards from the nucleus. The main extension is called the axon. It carries messages that leave the cell. Dendrites are smaller branches upon main branches to pass on electrical signals, in addition to information. A layer of phospholipids called the myelin sheath increase the cell’s ability to carry the electrical signals that pass between the nervous systems.

Peripheral Nervous System The Peripheral Nervous System is located throughout the body. Sensory organs, receptors, internal organs, and muscles are some parts of this system. The Peripheral Nervous System spreads outwards from the CNS. Each of the thirty-one spinal pairs of nerves contains a dorsal root and a ventral root that will relay the instructions to muscles and organs. Afferent neurons in the head carry information from the CNS through twelve cranial pairs of nerves. The Peripheral Nervous System contains the Somatic and the Autonomic Nervous Systems. Together, they respond to stimuli and maintain homeostasis.

Somatic Nervous System The Somatic Nervous System is also called the Voluntary Nervous System, whereas the Autonomic Nervous System is the Involuntary Nervous System. Compared to the Autonomic Nervous System, the SNS works consciously and purposefully. This nervous system contains the 31 pairs of spinal nerves and 12 pairs of cranial nerves. Smiling is a voluntary movement

Autonomic Nervous System The Autonomic Nervous System is also called the Involuntary Nervous System. It maintains homeostasis and works automatically and unconsciously. This nervous system contains receptors, sensory/internal organs, and smooth/cardiac muscles. The organs and receptor send information through efferent neurons while muscles and organs carry out the impulses. Fight or Flight is a sympathetic reaction where a sense of panic is achieved. Parasympathetic reactions inversely achieve a state of calm.

Diseases in the Human Nervous System Many different diseases can occur within the nervous system that affect the human body and its capabilities. Alzheimer’s disease, epilepsy, Huntington disease, Parkinson’s disease, and aphasia are some diseases that occur in this system. Diseases can be genetic or caused by trauma or injury(autoimmune disorders, disruption of the normal blood flow, tumors, or infection).

Aphasia Aphasia is the loss or inability of speech. When someone suffers from aphasia they can have difficulties understanding other people when they speak. They can also find that they have difficulty speaking or finding words. If the brain has suffered from a severe injury or they have suffered a stroke, these disabilities can occur.

Epilepsy Epilepsy is a disease where the patient can suffer seizures or convulsions in varying states of severity and durations of time, depending on the individual’s situation. Children can develop epilepsy if they suffer from a high fever. This condition can occur at any age. Strobe lights can result in seizures in those who suffer from epilepsy.

Conclusion While I was researching this presentation, I found many facts on the many parts of the Human Nervous System that I did not previously know. For example, I did not know about the myelin sheath on neurons that promote conductivity. I also learned more about aphasia, epilepsy, and diseases in the Human Nervous System. This activity benefited me by prompting me to learn more about this body system. Overall, I learned about the function of the Human Nervous System, the types of impulses that control responses, and the different components of the system.

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