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# Nervous System ## Peripheral Nervous System * **Sensory Parts** * Physical signals * Skin * Muscles * Senses ## Sensory Somatic * **(Composed of all nerves branching off of the spinal cord that extend to the rest of the body).** ## Central Nervous System * **Motor** * Cer...

# Nervous System ## Peripheral Nervous System * **Sensory Parts** * Physical signals * Skin * Muscles * Senses ## Sensory Somatic * **(Composed of all nerves branching off of the spinal cord that extend to the rest of the body).** ## Central Nervous System * **Motor** * Cerebellum * Spinal Cord **Note:** * Sympathetic system stimulates everything but the gastrointestinal system * Parasympathetic system inhibits everything but the gastrointestinal system. **Note:** * **Properties of Living Matter** * **Excitability:** The ability to react to physical and chemical stimuli * **Conductivity:** The ability to transmit excitement from one place to another ## Neuron * **Types of Neurons** * **Afferent:** Sensory or receptor neurons that carry signals from peripheral tissues to the CNS * Carry impulses from peripheral tissues to the CNS * **Efferent:** Motor or descending neurons that carry signals from the CNS to peripheral tissues * Carry impulses from the CNS to peripheral tissues **Soma:** Contains the nucleus and organelles; the control center of the neuron where incoming information is processed and metabolic functions occur. **Dendrites:** Short branching extensions of the soma that receive signals from other neurons and transmit them to the soma; act like antennae to capture information. **Axon:** A long, thin projection that stretches from the soma to the other neurons, muscles, or glands; transmits electrical signals **Myelin Sheath:** A fatty layer that covers the axon in some neurons; increases the transmission speed of nerve impulses and provides protection. **Nodes of Ranvier:** Gaps in the myelin sheath that allow the nerve impulse to jump from one node to the next, accelerating signal propagation. **Synaptic Buttons or Axon Terminals:** The ends of the axon where neurotransmitters are released; contact with dendrites of other neurons or cells transmit the signal. **Diagram Description:** A simple diagram of a neuron is present. It shows the soma, dendrites, axon, myelin sheath, nodes of Ranvier, and axon terminal. Labels are included to identify each part.