the systems, structures, and cells that make up your nervous system chapter 3 the anatomy of the...

The Systems, Structures, and Cells That Make Up Your Nervous System

Chapter 3The Anatomy 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

Major divisions of the nervous system

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

Meningeshttp://faculty.une.edu/com/fwillard/Meninges/pages/mening02.htm

http://faculty.une.edu/com/fwillard/Meninges/pages/mening02.htm

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 Neurons

Specialized cells for the reception, conduction, and transmission of electrochemical signals

Many sizes and shapes Glial cells

Outnumber neurons 10:1

Major external features of

a typical neuron

Cells of theNervousSystem

The cell

mem-brane

Cells of the Nervous System (continued)

Fourtypes

ofneurons

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 NoteCNS PNS

Myelin-providing glia

Oligodendrocytes Schwann cells

Clusters of cell bodies

Nuclei (singular nucleus)

Ganglia(singular ganglion)

Bundles of axons Tracts Nerves

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

Neuroanatomical Tracing Techniques

Anterograde (forward) tracing where axons project

away from an area Retrograde (backward)

tracing where axons are projecting into an area

Directions in the Vertebrate Nervous System

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

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

The Spinal Cord Gray matter – inner component,

primarily cell bodies White matter – outer area, mainly

myelinated axons Dorsal – afferent, sensory Ventral – efferent, motor

The Spinal Cord (continued)

Dorsal and ventral roots Spinal cross section

The Five Major Divisions of the Brain

Early develop-

ment of themammalian

The Five Major Divisions of the Brain (continued)

The divisionsof the adult

human brain

Major Structures of the Brain Myelencephalon = medulla

Composed largely of tracts Origin of the reticular formation

Metencephalon Many tracts Pons – ventral surface Cerebellum – coordination

Structures of thehuman

myelencephalon(medulla) and

metencephalon

Major Structures of the Brain

Major Struc-tures of theBrain (continued)

The humanmesencephalon

(midbrain)

(continued)

Major Structures of the Brain

The humandiencephalon

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

Major fissures of the cerebral hemispheres Lobes of the cerebral hemispheres

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

The major structures of

the limbicsystem

The basal ganglia

Summary of major brain structures

the systems, structures, and cells that make up your nervous system chapter 3 the anatomy of the...

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