Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Nervous System  The master controlling and communicating system of the body  Functions  Sensory input – monitoring stimuli occurring inside and outside the body  Integration – interpretation of sensory input  Motor output – response to stimuli by activating effector organs

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  The two principal cell types of the nervous system are:  Neurons –  excitable cells that transmit electrical signals  functional units of the nervous system  Neuroglia – supporting cells that surround and wrap neurons Histology of Nerve Tissue

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Composed of:  Cell body: Nucleus, Nissl bodies, Neurofibrils  Dendrites – receive signal  Axon – produce action potential & transmit signals  Axonal terminals contain neurotransmitter  Axon may have myelin sheath Neurons (Nerve Cells)

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Neurons (Nerve Cells) Figure 11.4b

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Whitish, fatty (protein-lipoid), segmented sheath around most long axons  It functions to:  Protect the axon  Electrically insulate fibers from one another  Increase the speed of nerve impulse transmission Myelin Sheath

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Myelin Sheath Formation The amount of myelin increases from infant to adult.

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Sensory (afferent) neuron — transmit impulses toward the CNS Motor (efferent) neuron — carry impulses away from the CNS Interneurons (association neurons) — shuttle signals through CNS pathways Neuron Classification: Functional

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Organization of the Nervous System  Central nervous system (CNS)  Integration and command center  Peripheral nervous system (PNS)  Sensory: carries messages to CNS  Motor: carries messages from CNS  If to skeletal muscles: Somatic N.S.  If to smooth muscles, cardiac muscle, or glands: Autonomic N.S.

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Principal Parts of the Brain  Cerebrum  Diencephalon  thalamus & hypothalamus  Brainstem  medulla, pons, & midbrain  Cerebellum

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  White matter –  dense collections of myelinated axons  functions in rapid communication  Gray matter –  mostly soma and unmyelinated fibers  functions in decisions, memory, etc. Regions of the Brain and Spinal Cord

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Darker areas are gray matter

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Cerebral White Matter Corpus Callosum: White matter that connects the two hemispheres together

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Cortex (gray matter) Fissure (a deep sulcus) Gryus Sulcus White matter Cerebral Gray Matter is the outer layer. Other gray matter are pockets call Basal Ganglia.

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Cerebrum Gyri: convolutions Sulci: grooves Fissure: large groove 5 Lobes: Frontal lobe Occipital lobe Temporal lobe Parietal lobe Insula lobe

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Diencephalon Hypothalamus Pineal gland Thalamus Pituitary Gland Intermediate mass of Thalamus

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Brain Stem Pons Medulla Midbrain: Cerebral peduncles Cerebral aquaduct Corpora quadrigemina

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Cerebellum

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Protection of the Brain/spinal cord - Meninges Bone (skull) Epidural Space: contains fat, blood vessels, etc. Dura Mater – “tough mother” Subdural Space: Dura Mater and Arachnoid are actually back to back – there is only small amount of interstitial fluid in this space Arachnoid – “like a spider web” Subarachnoid Space: contains cerebrospinal fluid (CSF) Pia Mater – “little or small mother” on surface of brain and spinal cord

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Origin of CSF  Choroid plexus (capillary network)  Found in all 4 ventricles

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Reabsorption of CSF  Reabsorbed through arachnoid villi  grapelike clusters of arachnoid penetrate dural venous sinus

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Flow of Cerebrospinal Fluid (cerebral aquaduct) Choroid Plexus of Lateral Ventricles Left & Right Lateral Ventricles Choroid plexus of 3 rd Ventricle Choroid plexus of 4 th Ventricle 4 th Ventricle Subarachnoid space & central canal of spinal cord 3 rd Ventricle Arachnoid villi BLOOD CSF