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The Nervous System

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FC: The Nervous System | By Michelle Hesseltine Period 1

1: The Neuron | Neurons are nerve cells. They are made up by a cell body and connecting fibers and it's their job to carry messages throughout our body. Without nerves and neurons we would be unable to function. There are many different parts of a neuron. The nucleus and cytoplasm make up the cell body which is like a control center of a neuron. The cell body makes sure the neurons systems are running smoothly. Extending from the cell body are dendrites and the axon. Dendrites are fibers that bring messages to the cell body. Basically they are like the receiver of a phone. The axon is a long fiber that carries messages away from the body, like telephone wires do when you make a call.

2: If the axon gets damaged or something some neurons also have something thats called neurilemma. Neurilemma help the axon grow. There is a space between each nerve cell, it's called a synapse. Synapse make sure the messages being sent throughout the body are going only one way. Protoplasm is the living matter of all cells. The matter of cells can be divided into two groups. The first is white matter. White matter is distinguished because it has a myelin sheath or covering whereas gray matter, the other type of matter, does not have a myelin sheath. | The Neuron

3: The Three Types of Neurons | Sensory Neurons Sensory neurons carry messages from the senses (taste, touch, smell, sight, hearing) to the brain and spinal cord. | Motor Neurons Motor neurons carry messages from the brain and spinal cord to muscles and glands of the body. | Association Neurons Association neurons connect the sensory neurons and the motor neurons and are located in the brain.

4: The Reflex | The reflex is something you do not have to learn to do it is a natural reaction. Reflexes are so fast your muscles move before you brain can even process what has happened. It is a protective mechanism. | Sensory neurons carry messages to the spinal cord. Then an association neuron carries it to a motor neuron. The motor neuron then causes the muscle to jerk.

5: The Central Nervous System | The central nervous system is made of the brain and spinal cord. Both the brain and the spinal cord are protected by bone, along with meanings, 3 tissues that protect their surfaces, and cerebrospinal fluid, shock absorbing fluid. The body has so many protective mechanisms because trauma to the brain or spinal cord can be

6: The Central Nervous System | cause extreme disabilities of death. Injury to the brain can result in loss of speech, the ability to think, the ability to feed yourself and so on. Injury to the spinal cord can cause a person to become paralyzed. The brain has different sections for different tasks. The top of the brain is called the cerebrum. The cerebrum is in charge of receiving sensory message, controlling muscles and allowing us to think. The middle section of the brain is called the cerebellum. The cerebellum coordinates the muscles. The final part of the brain is the medulla oblongata at the bottom of the brain, which controls all the bodies vitals like heart beat, and it connects to the spinal cord.

7: The Cerebrum | The cerebrum is the largest part of the brain. The surface area of the cerebrum is called the cortex. The cortex is folded in ridges called convolutions, and is the control board. One large ridge, or fissure, divides the cerebrum into two hemispheres. The motor area of the cerebrum is about two inches wide and is located between the ears. Opposite sides of the cerebrum control the other sides of the body.

8: The Cerebrum | Consciousness is defined as being aware and able to interpret sensation. In other word being awake and at least semi alert. Behind the motor area is the part of the brain that receives nerve messages for touch. The rear part of the brain is dedicated to sight. The lower area of the brain is for speech, hearing, taste, and smell. The second layer of the cerebrum is called the cerebral medulla. The cerebral medulla makes connections throughout the brain.

9: The Cerebellum, Medulla, and Spinal Cord | The cerebellum is divided into two hemispheres and is folded. The cerebellum is in charge of balance and coordination. Injuries to the cerebellum may result in jerky, unpredictable movements. The medulla is made up of white matter on the outside and gray matter on the inside. The white matter receives messages from higher parts of the brain. The gray matter acts as a switch board for sensory and motor messages. Some of the gray matter also controls the bodies vitals. | The spinal cord is a bundle of nerves attached to 31 pairs of nerves with messages. Some of the nerves carry messages to the brain while others send messages to muscles and glands.

10: The Peripheral Nervous System | The peripheral nervous system connects the brain and spinal cord to the rest of the body with 43 pairs of large nerves. 12 pairs of nerves that connect to the brain and involve sight, balance, etc. are called cranial nerves. The vagus, the longest cranial nerve, connects to internal organs. The other 31 pairs of nerves, called spinal nerves, connect to the spinal cord and extend to all areas of the body. The autonomic nervous system is made up of some cranial and spinal nerves. Autonomic nerves control digestion and other internal activities that are often not thought about since the body just does them. There are two divisions of Autonomic nerves.

11: The first division of the autonomic nervous system is the parasympathetic division. This division is in charge of slowing or restricting activities, such as slowing the heartbeat or respiration of the body. | The second division is the sympathetic division. The sympathetic division speeds bodily functions up, like making the heartbeat or respiration faster.

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  • By: Michelle H.
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