The Nervous System

1. The Nervous System The central nervous system & The peripheral nervous system

2. The Central and Peripheral Nervous System The Central Nervous System: The Central Nervous System consists of the brain and the spinal cord, and processes information and creates a response that is delivered to the appropriate part of the body through the peripheral nervous system The Peripheral Nervous System: The Peripheral Nervous System consists of nerves and supporting cells, and collects information about the body’s external and internal environment.

3. Brain The brain contains billions of neurons and other supporting tissue that process, relay, and form responses to an incomprehensible amount of information every moment. Frontal Lobe: The frontal Lobe is used for evaluating consequences, making judgments, and forming plans. Temporal Lobe: ]The temporal lobe is used for hearing and smelling. Cerebellum: The used for storing information about muscle and joint positions. Occipital Lobe: The occipital lobe is used for vision. Parietal lobe: The parietal lobe is used for reading and speech. Spinal Cord: The parietal lobe is used for reading and speech. The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain

4. Spinal Cord The spinal cord is the main communication link between the brain and the rest of the body. • The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain. • The spinal cord functions primarily in the transmission of neural signals between the brain and the rest of the body but also contains neural circuits that can independently control numerous reflexes and central pattern generators. • Thirty-one pairs of spinal nerves branch out from the spinal cord which connect the brain to different parts of the body.

5. Neurons Neurons are nervous system impulses that are transmitted by cells. They are classified according to the direction an impulse travels. They carry impulses from the brain to the muscles and glands. Interneurons process information from sensory neurons and send commands to other interneurons. They all have certain common features. They all have nuclei, cell bodies, dendrites, axons, nodes, axon endings/terminals, and myelin sheaths. The nucleus serves the purpose of controlling the cell. The cell body hold the nucleus and the cytoplasm, and is the largest part of the neuron. Dendrites receive impulses from other neurons And carry impulses to the cell body Axons carry impulses away from the body. Nodes are along the myelin sheaths which surround the neuron. Axon endings and terminals are the endings and swellings of axons. Myelin sheaths are insulating membranes. This surrounds a single, long axon that has many gaps, called nodes, where the axon membrane is exposed.

6. The Nerves Neurons are the thin threads of nerve cells that run throughout your body. Bundled together, they carry messages back and forth just the way that telephone wires do. When a neuron is stimulated, it begins to actually generate a tiny electrical pulse. This electricity and chemical change travels the full length of the neuron. Nerves are axons and dendrites of different neurons that are clustered into bundles of fibers. Some contain fibers from only a few neurons, others contain hundreds. Each type of nerve serves a different purpose. For example, sensory nerves send messages to the brain and connect to the brain through the spinal cord. Motor nerves carry messages back from the brain. Nerve impulses in a way are kind of like the flow of an electric current. The impulse begins when a neuron is stimulated by another neuron or its environment. A stimulus like touch or pain, create these impulses. A nerve impulse first travels down the axon from the cell body out to the axon terminals. At the leading edge of the impulse, gated sodium channels open which allows positive charged Na ions to flow into the cell making it positive. Once an impulse passes the sodium gates close allowing K ions to flow out restoring the resting potential so that it is negative again. At the end of the neuron when the impulse reaches the axon terminal, it passes the impulse along to another cell. This is called synapse. When the impulse arrives to this, neurotransmitters are released from the axon and bind to receptors on the membrane of the receiving cell.  

7. Ways in which the Nervous System works with other systems within the body. The Nervous System works with the Skeletal System because bones provide calcium that is essential for the proper functioning of the Nervous System. It also works with the Cardiovascular System because the brain helps regulate heart rate and blood pressure. The Nervous System works with the Muscular System because receptors in muscles provide the brain with information about body position and movement. It also works with the Respiratory System because the brain monitors respiratory volume and blood gas levels.

8. Fun Facts about the Nervous System The human nervous system is divided into two parts, the central nervous system and the peripheral nervous system. If joined end to end, your nerves would stretch sixty-two miles. If we lined up all the neurons in your body, it would be around six-hundred miles long. There are about thirteen-million-five-hundred-thousand neurons in the human spinal cord. Humans on average use only four percent of the cells in their brain at one time.