PSYCH 100 Study Guide - Midterm Guide: Limbic System, Curare, Heritability
Document Summary
Topics included: neurons, the central nervous system, the peripheral nervous system, the endocrine system, genes, evolution, and behavior. There are about 100 billion neurons (nerve cells) in the human brain. Neurons have many of the same features as other cells: nucleus, cytoplasm, cell membrane. The myelin sheath is made up of glial cells (or glia), which insulate and support neurons by holding them together, provide nourishment and remove waste products, and prevent harmful substances from passing into the brain. Because of the white covering, tissues made up primarily of myelinated axons are known as white matter, whereas tissues made up primarily of unmyelinated axons are called gray matter. The speed at which neurons carry impulses varies widely, from as fast as nearly 400 feet per second on largely myelinated axons to as slow as about 3 feet per second on those with no myelin.
