BIOL 221 Chapter 5 Lecture Outline The Central Nervous System

BIOL 221 Chapter 5 Lecture Outline The Central Nervous System The nervous system is one fully integrated system with divisions based on differences in structure, location, and function There are 4 main functions of the nervous system 1) respond to chemical and physical stimuli 2) conduct electrochemical impulses 3) release chemical regulators 4) enable perception of sensory stimuli, learning, memory, and control of muscles and glands Glial Cells Glial cells are also known as neuroglia and are found throughout the central and peripheral nervous systems. They have 2 important characteristics 1) Do not initiate or conduct nerve impulses 2) Serve as connective tissue of the CNS There are 4 major types of glial cells found in the CNS 1) Astrocytes 2) Oligodendrocytes 3) Microglia 4) Ependymal Cells Glial Cells (continued) Astrocytes most abundant glial cells has 7 functions 1) Holds neurons together 2) Guides neurons during fetal brain development 3) Helps establish the Blood brain barrier 4) important in repair of brain injuries and neural scar information 5) play a role in neurotransmitters activity 6) take up excess potassium from brain ECF 7) Enhance synapse formation and modify synaptic transmission Oligodendrocytes: Form myelin sheath around axons in CNS Microglia: Immune cells in the CNS. Have different functions depending on their state Active state: Act as immune defense cells of the CNS Resting state: release low levels of growth factor (NGF) that help neurons and other glial cells survive and thrive Ependymal cell: Line the internal, fluid filled cavities of the CNS Function: Help form and circulate cerebrospinal fluid Protection of the CNS The CNS is protected by 2 1) Bones: skull & vertebral column 2) Meninges: Dura Mater, arachnoid mater, pia mater 3 3) Glial Cells 4) Cerebral Spinal Fluid: extracellular fluid that support & protects neurons 5) Blood brain barrier: the separation of blood & CNS