The Systems, Structures, and Cells That Make Up Your Nervous System Chapter 3 The Anatomy of the Nervous System The Systems, Structures, and Cells That Make Up Your 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 Copyright © 2009 Allyn & Bacon
Copyright © 2009 Allyn & Bacon Major divisions of the nervous system Copyright © 2009 Allyn & Bacon
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 Copyright © 2009 Allyn & Bacon
Meninges http://faculty. une. edu/com/fwillard/Meninges/pages/mening02 http://faculty.une.edu/com/fwillard/Meninges/pages/mening02.htm
Copyright © 2009 Allyn & Bacon 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) Copyright © 2009 Allyn & Bacon
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 Copyright © 2009 Allyn & Bacon
Cells of the Nervous System Major external features of a typical neuron Copyright © 2009 Allyn & Bacon
Copyright © 2009 Allyn & Bacon Cells of the Nervous System (continued) The cell mem- brane Copyright © 2009 Allyn & Bacon
Cells of the Nervous System (continued) Four types of neurons Copyright © 2009 Allyn & Bacon
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 Copyright © 2009 Allyn & Bacon
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Copyright © 2009 Allyn & Bacon Terminology Note CNS PNS Myelin-providing glia Oligodendrocytes Schwann cells Clusters of cell bodies Nuclei (singular nucleus) Ganglia (singular ganglion) Bundles of axons Tracts Nerves Copyright © 2009 Allyn & Bacon
Neuroanatomical Techniques Golgi stain – allows for visualization of individual neurons Nissl stain – selectively stains cell bodies Electron microscopy – provides information about the details of neuronal structure Copyright © 2009 Allyn & Bacon
Neuroanatomical Tracing Techniques Anterograde (forward) tracing where axons project away from an area Retrograde (backward) tracing where axons are projecting into an area Copyright © 2009 Allyn & Bacon
Copyright © 2009 Allyn & Bacon Directions in the Vertebrate Nervous System Copyright © 2009 Allyn & Bacon
Copyright © 2009 Allyn & Bacon Directions in the Vertebrate Nervous System (continued) Copyright © 2009 Allyn & Bacon
Directions in the Vertebrate Nervous System (continued) Anatomical directions ignore the fact that humans walk upright. Therefore, top of the head both “dorsal” (back) and “superior” (top) Other directions: Medial – toward the middle Lateral – toward the side Proximal – close Distal – far Copyright © 2009 Allyn & Bacon
Copyright © 2009 Allyn & Bacon Sections of the Brain Horizontal – a slice parallel to the ground Frontal (coronal) – slicing bread or salami Sagittal – a midsagittal section separates the left and right halves Copyright © 2009 Allyn & Bacon
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Copyright © 2009 Allyn & Bacon The Spinal Cord Gray matter – inner component, primarily cell bodies White matter – outer area, mainly myelinated axons Dorsal – afferent, sensory Ventral – efferent, motor Copyright © 2009 Allyn & Bacon
The Spinal Cord (continued) Dorsal and ventral roots Spinal cross section Copyright © 2009 Allyn & Bacon
The Five Major Divisions of the Brain Early develop- ment of the mammalian brain Copyright © 2009 Allyn & Bacon
The Five Major Divisions of the Brain (continued) The divisions of the adult human brain Copyright © 2009 Allyn & Bacon
Major Structures of the Brain Myelencephalon = medulla Composed largely of tracts Origin of the reticular formation Metencephalon Many tracts Pons – ventral surface Cerebellum – coordination Copyright © 2009 Allyn & Bacon
Copyright © 2009 Allyn & Bacon Major Structures of the Brain Structures of the human myelencephalon (medulla) and metencephalon Copyright © 2009 Allyn & Bacon
Copyright © 2009 Allyn & Bacon Major Struc- tures of the Brain (continued) The human mesencephalon (midbrain) Copyright © 2009 Allyn & Bacon
Copyright © 2009 Allyn & Bacon Major Structures of the Brain (continued) The human diencephalon Copyright © 2009 Allyn & Bacon
Telencephalon – Cerebral Cortex Convolutions serve to increase surface area Longitudinal fissure – a groove that separates right and left hemispheres Corpus callosum – largest hemisphere-connecting tract Copyright © 2009 Allyn & Bacon
Copyright © 2009 Allyn & Bacon Major fissures of the cerebral hemispheres Lobes of the cerebral hemispheres Copyright © 2009 Allyn & Bacon
Telencephalon – Subcortical Structures Limbic system – regulation of motivated behaviors Mammillary bodies, hippocampus, amygdala, fornix, cingulate, septum Basal ganglia motor system Amygdala, striatum (caudate nucleus + putamen), globus pallidus Copyright © 2009 Allyn & Bacon
Telencephalon – Subcortical Structures The major structures of the limbic system Copyright © 2009 Allyn & Bacon
Copyright © 2009 Allyn & Bacon Telencephalon – Subcortical Structures The basal ganglia Copyright © 2009 Allyn & Bacon
Summary of major brain structures Copyright © 2009 Allyn & Bacon