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The Nervous System

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S: The Nervous System

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FC: The Nervous System | The busiest place in our bodies. | By Karissa Renyer

1: Table of Contents | 1.) The Neuron............................................................................... 2.) The Three Types of Neurons.................................................... 3.) The Reflex.................................................................................. 4.) The Central Nervous System.................................................... 5.) The Cerebrum............................................................................ 6.) The Cerebellum, Medulla, and Spinal Cord............................. 7.) The Peripheral Nervous System............................................... 8.) Ways to Take Care of the Nervous System.............................. | 3 4 5 6 7 8 9 10

3: The Neuron | Nerves are often compared to telephone wires; they carry messages all over the body. Each nerve is made of cells, and these specific cells are called neurons. A neuron is made of a cell body and a few connecting fibers. Containing a nucleus and being surrounded by cytoplasm, a cell body is the control center of the cell. Growing out of the cell are thread-like fibers that carry messages around. While dendrites send messages away from the cell, the axon carries messages to it. At the end of the axon, it starts to branch out to things called end plates, which keep a message from going the wrong way. Most axons have a neurilemma covering that allows it to be regrown. Some neurons have a myelin sheath around them. This helps keep the messages on the right wire and insulates the nerve. | 3

4: The Three Types of Neurons | Sensory, association, and motor are the three types of neurons. The sensory neurons pick up messages from the eyes, skin, ears, nose, and tongue and send them towards the brain and spinal cord. Association neurons take the messages from the sensory neurons and transfer them to the motor neurons. The motor neurons then transfer the message to a muscle, making it move, or a gland, where there is a secretion. These important neurons keep the brain up to date on what is happening to the body, and they can send messages originated in the brain to various tissues and organs in the body. | Neuron Synapse | 4

5: The Reflex | Reflexes are imperative because they are mechanisms that help protect us. Sneezing, coughing, and blinking are all examples of reflexes. Another example is when a person goes to the doctor's office for a checkup, and the doctor hits the patients leg. If the patient's leg jerks up, then the reflexes are healthy. When the doctor hits the leg, a nerve message is carried by a sensory neuron to the spinal cord. From there, the message is transferred to an association neuron, which then passes it off to a motor neuron. Then motor neurons travels down the leg to a muscle. The muscle contracts and the leg moves. Reflex means "to turn back" because the impulse is "turned back" to a place near where it began. | 5

6: The Central Nervous System | The human communication system has a main switchboard made of the brain and spinal cord; it's called the central nervous system. Being vital to survival, the brain and spinal cord are enclosed by bones. The cranium of the skull protects the brain and the vertebrae keep the spinal cord safe. There are three main areas of the brain: the cerebrum, cerebellum, and medulla oblongata. The cerebrum controls muscles, allows a person to think, receives sensory messages from the body, and forms the top of the brain. Coordinating the muscles, the cerebellum is located underneath and behind the cerebrum. Finally, the medulla oblongata regulates vital activities like breathing, the heart rate, and digestion. It's the lower part of the brain; it attaches to the spinal cord. | 6

7: The Cerebrum | Being made of gray and white matter, the cerebrum is the largest part of the brain. The cortex, or the surface area, is folded into ridges called convolutions. It is the control board of the nervous system. Each area of the cerebral cortex has a particular job to do. The motor area controls the muscles; it's about two inches wide and runs over the brain between the ears (like a headband). Behind the motor area is where nerve messages having to do with touch are found. Located in the rear of the cerebrum are the sight sensations. Taste, speech, hearing, and smell, are in the lower part of the cerebrum. All of these senses and their interpretations are known as our consciousness. The cortex has to function together, so lots of nerve cells connect the different parts. There are also additional connections made in a second layer of the cerebrum called the cerebral medulla. | 7

8: 8 | The Cerebellum, Medulla, and Spinal Cord | Like the cerebrum, the cerebellum is composed of gray and white matter and the surface of it is folded. The cerebellum's main job is to control balance and coordination. It's located below and behind the cerebrum. The medulla oblongata is the lowest part of the brain. Attached to the spinal cord, it's composed of white and gray matter. The white matter, located on the outside, is a pathway for nerve passages from higher brain parts. The gray matter is a switchboard for sensory messages going to the central nervous system and motor neurons going to a gland or muscle. Some of the gray matter though is used to control the body's necessary life functions. The spinal cord is a long bundle of nerves located in the vertebral column. It has 31 nerve pairs attached to it. These nerves carry messages to and from the spinal cord. Only some messages go to the brain; the others go to muscles and glands. | Medulla | Cerebellum | Spinal Cord

9: 9 | The peripheral nervous system connects the central nervous system to all the other body parts. It's made up of 43 pairs of large nerves. Out of 43 peripheral nerves, 12 are cranial. These nerves take messages from the eyes, nose, tongue, the balance, and a few other functions and send them to the brain. The longest cranial nerve, called the vagus nerve, supplies a connection to the internal organs. The spine's 31 pairs of peripheral nerves are called spinal nerves. They are connected to most of the outside of the body. Some peripheral nerves are autonomic nerves. They control digestion, respiration, and circulation. The brain doesn't have to think for these actions to take place. For example, the vagus nerve is autonomic. In the autonomic nervous system, there are two divisions. One division called the parasympathetic slows down activities. The other division, the sympathetic, speeds things up. | The Peripheral Nervous System

10: Ways to Take Care of One's Nervous System | The nervous system is important, so one needs to protect it. Here are some things to do if one wants to keep their nervous system healthy. 1.) Stay away from drugs. They can not only damage one's nervous system, but they can harm other parts of the brain as well. Even everyday over-the-counter and prescription medications can be dangerous if they aren't taken as directed. 2.) Don't drink. Alcohol slows down the brain and can permanently damage it. Plus it is illegal to consume alcohol if one is under the age of 21. 3.) Keep clear of violent sports and activities. If one gets a serious neck injury, they can become paralyzed or even die. | 10

11: Dirt Biking | Drugs | Alcohol | Stay away from these these things to keep one's Nervous System healthy! | 11

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Jennifer Renyer
  • By: Jennifer R.
  • Joined: over 6 years ago
  • Published Mixbooks: 5
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About This Mixbook

  • Title: The Nervous System
  • A book about the nervous system
  • Tags: None
  • Published: about 5 years ago

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