Ch 3: Neurons and Glia

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Slide 1:The Systems, Structures, and Cells That Make Up Your Nervous System Chapter 3 The Anatomy of the Nervous System

General Layout of the Nervous System :General Layout of the Nervous System Central Nervous System (CNS) Brain (in the skull) Spinal Cord (in the spine) Peripheral Nervous System (PNS) Located outside of the skull and spine Serves to bring information into the CNS and carry signals out of the CNS

General Layout of the Nervous System (continued) :General Layout of the Nervous System (continued) Peripheral Nervous System Somatic Nervous System Afferent nerves (sensory) Efferent nerves (motor) Autonomic Nervous System Sympathetic and parasympathetic nerves Both are efferent

Autonomic Nervous System :Autonomic Nervous System All nerves are efferent Sympathetic and parasympathetic nerves generally have opposite effects Two-stage neural paths, neuron exiting the CNS synapses on a second-stage neuron before the target organ

Autonomic Nervous System(continued) :Autonomic Nervous System(continued) Sympathetic Thoracic and lumbar “Fight or flight” Second stage neurons are far from the target organ Parasympathetic Cranial and sacral “Rest and restore” Second stage neurons are near the target organ

Slide 6:Major divisions of the nervous system

Meninges, Ventricles, and Cerebrospinal Fluid (CSF) :Meninges, Ventricles, and Cerebrospinal Fluid (CSF) CNS encased in bone and covered by three meninges Dura mater – tough outer membrane Arachnoid membrane – web-like Pia mater – adheres to CNS surface Cerebrospinal fluid (CSF) Fluid serves as cushion

Protecting the Brain :Protecting the Brain Chemical protection The blood-brain barrier – tightly-packed cells of blood vessel walls prevent entry of many molecules Physical protection Skull Meninges Cerebrospinal fluid (CSF)

Cells of the Nervous System :Cells of the Nervous System Neurons Specialized cells for the reception, conduction, and transmission of electrochemical signals Many sizes and shapes Glial cells Outnumber neurons 10:1

Slide 10:Major external features of a typical neuron Cells of the Nervous System

Slide 11:The cell mem- brane Cells of the Nervous System (continued)

Slide 12:Cells of the Nervous System (continued) Four types of neurons

Glial Cells: The Forgotten Majority :Glial Cells: The Forgotten Majority Four classes: Oligodendrocytes – extensions rich in myelin create myelin sheaths in CNS Schwann cells – similar to function of oligodendrocytes but in PNS, can guide axonal regeneration Astrocytes – largest glia, star-shaped, many functions Microglia – involved in response to injury or disease

Terminology Note :Terminology Note