The Nervous System PDF

7 PART A The Nervous System PowerPoint® Lecture Slide Presentation by Jerry L. Cook, Sam Houston University ESSENTIALS...

7 PART A The Nervous System PowerPoint® Lecture Slide Presentation by Jerry L. Cook, Sam Houston University ESSENTIALS OF HUMAN ANATOMY & PHYSIOLOGY EIGHTH EDITION ELAINE N. MARIEB Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functions of the Nervous System  Sensory input – gathering information  To monitor changes occurring inside and outside the body  Changes = stimuli  Integration  To process and interpret sensory input and decide if action is needed Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functions of the Nervous System  Motor output  A response to integrated stimuli  The response activates muscles or glands Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Structural Classification of the Nervous System  Central nervous system (CNS)  Brain  Spinal cord  Peripheral nervous system (PNS)  Nerve outside the brain and spinal cord Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functional Classification of the Peripheral Nervous System  Sensory (afferent) division  Nerve fibers that carry information to the central nervous system Figure 7.1 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functional Classification of the Peripheral Nervous System  Motor (efferent) division  Nerve fibers that carry impulses away from the central nervous system Figure 7.1 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functional Classification of the Peripheral Nervous System  Motor (efferent) division  Two subdivisions  Somatic nervous system = voluntary  Autonomic nervous system = involuntary Figure 7.1 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Organization of the Nervous System Figure 7.2 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Nervous Tissue: Support Cells (Neuroglia)  Astrocytes  Abundant, star-shaped cells  Brace neurons  Form barrier between capillaries and neurons  Control the chemical environment of the brain Figure 7.3a Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Nervous Tissue: Support Cells  Microglia  Spider-like phagocytes  Dispose of debris  Ependymal cells  Line cavities of the brain and spinal cord  Circulate cerebrospinal fluid Figure 7.3b–c Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Nervous Tissue: Support Cells  Oligodendrocytes  Produce myelin sheath around nerve fibers in the central nervous system Figure 7.3d Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Nervous Tissue: Support Cells  Satellite cells  Protect neuron cell bodies  Schwann cells  Form myelin sheath in the peripheral nervous system Figure 7.3e Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Nervous Tissue: Neurons  Neurons = nerve cells  Cells specialized to transmit messages  Major regions of neurons  Cell body – nucleus and metabolic center of the cell  Processes – fibers that extend from the cell body Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Neuron Anatomy  Cell body  Nissl substance – specialized rough endoplasmic reticulum  Neurofibrils – intermediate cytoskeleton that maintains cell shape Figure 7.4a Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Neuron Anatomy  Cell body  Nucleus  Large nucleolus Figure 7.4a–b Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Neuron Anatomy  Extensions outside the cell body  Dendrites – conduct impulses toward the cell body  Axons – conduct impulses away from the cell body Figure 7.4a Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Axons and Nerve Impulses  Axons end in axonal terminals  Axonal terminals contain vesicles with neurotransmitters  Axonal terminals are separated from the next neuron by a gap  Synaptic cleft – gap between adjacent neurons  Synapse – junction between nerves Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Nerve Fiber Coverings  Schwann cells – produce myelin sheaths in jelly-roll like fashion  Nodes of Ranvier – gaps in myelin sheath along the axon Figure 7.5 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Neuron Cell Body Location  Most are found in the central nervous system  Gray matter – cell bodies and unmylenated fibers  Nuclei – clusters of cell bodies within the white matter of the central nervous system  Ganglia – collections of cell bodies outside the central nervous system Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functional Classification of Neurons  Sensory (afferent) neurons  Carry impulses from the sensory receptors  Cutaneous sense organs  Proprioceptors – detect stretch or tension  Motor (efferent) neurons  Carry impulses from the central nervous system Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functional Classification of Neurons  Interneurons (association neurons)  Found in neural pathways in the central nervous system  Connect sensory and motor neurons Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Neuron Classification Figure 7.6 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Structural Classification of Neurons  Multipolar neurons – many extensions from the cell body Figure 7.8a Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Structural Classification of Neurons  Bipolar neurons – one axon and one dendrite Figure 7.8b Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Structural Classification of Neurons  Unipolar neurons – have a short single process leaving the cell body Figure 7.8c Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functional Properties of Neurons  Irritability – ability to respond to stimuli  Conductivity – ability to transmit an impulse  The plasma membrane at rest is polarized  Fewer positive ions are inside the cell than outside the cell Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Starting a Nerve Impulse  Depolarization – a stimulus depolarizes the neuron’s membrane  A deploarized membrane allows sodium (Na+) to flow inside the membrane  The exchange of ions initiates an action potential in the neuron Figure 7.9a–c Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Action Potential  If the action potential (nerve impulse) starts, it is propagated over the entire axon  Potassium ions rush out of the neuron after sodium ions rush in, which repolarizes the membrane  The sodium-potassium pump restores the original configuration  This action requires ATP Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Nerve Impulse Propagation  The impulse continues to move toward the cell body  Impulses travel faster when fibers have a myelin sheath Figure 7.9d–f Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Continuation of the Nerve Impulse between Neurons  Impulses are able to cross the synapse to another nerve  Neurotransmitter is released from a nerve’s axon terminal  The dendrite of the next neuron has receptors that are stimulated by the neurotransmitter  An action potential is started in the dendrite Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings How Neurons Communicate at Synapses Figure 7.10 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  7 PART B The Nervous System PowerPoint® Lecture Slide Presentation by Jerry L. Cook, Sam Houston University ESSENTIALS OF HUMAN ANATOMY & PHYSIOLOGY EIGHTH EDITION ELAINE N. MARIEB Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Reflex Arc  Reflex – rapid, predictable, and involuntary responses to stimuli  Reflex arc – direct route from a sensory neuron, to an interneuron, to an effector Figure 7.11a Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Simple Reflex Arc Figure 7.11b–c Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Types of Reflexes and Regulation  Autonomic reflexes  Smooth muscle regulation  Heart and blood pressure regulation  Regulation of glands  Digestive system regulation  Somatic reflexes  Activation of skeletal muscles Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Central Nervous System (CNS)  CNS develops from the embryonic neural tube  The neural tube becomes the brain and spinal cord  The opening of the neural tube becomes the ventricles  Four chambers within the brain  Filled with cerebrospinal fluid Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Regions of the Brain  Cerebral hemispheres  Diencephalon  Brain stem  Cerebellum Figure 7.12b Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cerebral Hemispheres (Cerebrum)  Paired (left and right) superior parts of the brain  Include more than half of the brain mass Figure 7.13a Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cerebral Hemispheres (Cerebrum)  The surface is made of ridges (gyri) and grooves (sulci) Figure 7.13a Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Lobes of the Cerebrum  Fissures (deep grooves) divide the cerebrum into lobes  Surface lobes of the cerebrum  Frontal lobe  Parietal lobe  Occipital lobe  Temporal lobe Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Lobes of the Cerebrum Figure 7.15a Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Specialized Areas of the Cerebrum  Somatic sensory area – receives impulses from the body’s sensory receptors  Primary motor area – sends impulses to skeletal muscles  Broca’s area – involved in our ability to speak Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Sensory and Motor Areas of the Cerebral Cortex Figure 7.14 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Specialized Areas of the Cerebrum  Cerebral areas involved in special senses  Gustatory area (taste)  Visual area  Auditory area  Olfactory area Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Specialized Areas of the Cerebrum  Interpretation areas of the cerebrum  Speech/language region  Language comprehension region  General interpretation area Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Specialized Areas of the Cerebrum Figure 7.13c Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Layers of the Cerebrum  Gray matter  Outer layer  Composed mostly of neuron cell bodies Figure 7.13a Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Layers of the Cerebrum  White matter  Fiber tracts inside the gray matter  Example: corpus callosum connects hemispheres Figure 7.13a Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Layers of the Cerebrum  Basal nuclei – internal islands of gray matter Figure 7.13a Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Diencephalon  Sits on top of the brain stem  Enclosed by the cerebral heispheres  Made of three parts  Thalamus  Hypothalamus  Epithalamus Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Diencephalon Figure 7.15 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Thalamus  Surrounds the third ventricle  The relay station for sensory impulses  Transfers impulses to the correct part of the cortex for localization and interpretation Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hypothalamus  Under the thalamus  Important autonomic nervous system center  Helps regulate body temperature  Controls water balance  Regulates metabolism Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hypothalamus  An important part of the limbic system (emotions)  The pituitary gland is attached to the hypothalamus Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Epithalamus  Forms the roof of the third ventricle  Houses the pineal body (an endocrine gland)  Includes the choroid plexus – forms cerebrospinal fluid Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Brain Stem  Attaches to the spinal cord  Parts of the brain stem  Midbrain  Pons  Medulla oblongata Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Brain Stem Figure 7.15a Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Midbrain  Mostly composed of tracts of nerve fibers  Has two bulging fiber tracts – cerebral peduncles  Has four rounded protrusions – corpora quadrigemina  Reflex centers for vision and hearing Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Pons  The bulging center part of the brain stem  Mostly composed of fiber tracts  Includes nuclei involved in the control of breathing Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Medulla Oblongata  The lowest part of the brain stem  Merges into the spinal cord  Includes important fiber tracts  Contains important control centers  Heart rate control  Blood pressure regulation  Breathing  Swallowing  Vomiting Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Reticular Formation  Diffuse mass of gray matter along the brain stem  Involved in motor control of visceral organs  Reticular activating system plays a role in awake/sleep cycles and consciousness Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Reticular Formation Figure 7.15b Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  7 PART C The Nervous System PowerPoint® Lecture Slide Presentation by Jerry L. Cook, Sam Houston University ESSENTIALS OF HUMAN ANATOMY & PHYSIOLOGY EIGHTH EDITION ELAINE N. MARIEB Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cerebellum  Two hemispheres with convoluted surfaces  Provides involuntary coordination of body movements Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cerebellum Figure 7.15a Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Protection of the Central Nervous System  Scalp and skin  Skull and vertebral column  Meninges Figure 7.16a Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Protection of the Central Nervous System  Cerebrospinal fluid  Blood brain barrier Figure 7.16a Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Meninges  Dura mater  Double-layered external covering  Periosteum – attached to surface of the skull  Meningeal layer – outer covering of the brain  Folds inward in several areas Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Meninges  Arachnoid layer  Middle layer  Web-like  Pia mater  Internal layer  Clings to the surface of the brain Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cerebrospinal Fluid  Similar to blood plasma composition  Formed by the choroid plexus  Forms a watery cushion to protect the brain  Circulated in arachnoid space, ventricles, and central canal of the spinal cord Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Ventricles and Location of the Cerebrospinal Fluid Figure 7.17a–b Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Ventricles and Location of the Cerebrospinal Fluid Figure 7.17c Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Blood Brain Barrier  Includes the least permeable capillaries of the body  Excludes many potentially harmful substances  Useless against some substances  Fats and fat soluble molecules  Respiratory gases  Alcohol  Nicotine  Anesthesia Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Traumatic Brain Injuries  Concussion  Slight brain injury  No permanent brain damage  Contusion  Nervous tissue destruction occurs  Nervous tissue does not regenerate  Cerebral edema  Swelling from the inflammatory response  May compress and kill brain tissue Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cerebrovascular Accident (CVA)  Commonly called a stroke  The result of a ruptured blood vessel supplying a region of the brain  Brain tissue supplied with oxygen from that blood source dies  Loss of some functions or death may result Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Alzheimer’s Disease  Progressive degenerative brain disease  Mostly seen in the elderly, but may begin in middle age  Structural changes in the brain include abnormal protein deposits and twisted fibers within neurons  Victims experience memory loss, irritability, confusion and ultimately, hallucinations and death Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Spinal Cord  Extends from the medulla oblongata to the region of T12  Below T12 is the cauda equina (a collection of spinal nerves)  Enlargements occur in the cervical and lumbar regions Figure 7.18 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Spinal Cord Anatomy  Exterior white mater – conduction tracts Figure 7.19 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Spinal Cord Anatomy  Internal gray matter - mostly cell bodies  Dorsal (posterior) horns  Anterior (ventral) horns Figure 7.19 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Spinal Cord Anatomy  Central canal filled with cerebrospinal fluid Figure 7.19 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Spinal Cord Anatomy  Meninges cover the spinal cord  Nerves leave at the level of each vertebrae  Dorsal root  Associated with the dorsal root ganglia – collections of cell bodies outside the central nervous system  Ventral root Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Peripheral Nervous System  Nerves and ganglia outside the central nervous system  Nerve = bundle of neuron fibers  Neuron fibers are bundled by connective tissue Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Structure of a Nerve  Endoneurium surrounds each fiber  Groups of fibers are bound into fascicles by perineurium  Fascicles are bound together by epineurium Figure 7.20 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Classification of Nerves  Mixed nerves – both sensory and motor fibers  Afferent (sensory) nerves – carry impulses toward the CNS  Efferent (motor) nerves – carry impulses away from the CNS Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cranial Nerves  12 pairs of nerves that mostly serve the head and neck  Numbered in order, front to back  Most are mixed nerves, but three are sensory only Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Distribution of Cranial Nerves Figure 7.21 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cranial Nerves  I Olfactory nerve – sensory for smell  II Optic nerve – sensory for vision  III Oculomotor nerve – motor fibers to eye muscles  IV Trochlear – motor fiber to eye muscles Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cranial Nerves  V Trigeminal nerve – sensory for the face; motor fibers to chewing muscles  VI Abducens nerve – motor fibers to eye muscles  VII Facial nerve – sensory for taste; motor fibers to the face  VIII Vestibulocochlear nerve – sensory for balance and hearing Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cranial Nerves  IX Glossopharyngeal nerve – sensory for taste; motor fibers to the pharynx  X Vagus nerves – sensory and motor fibers for pharynx, larynx, and viscera  XI Accessory nerve – motor fibers to neck and upper back  XII Hypoglossal nerve – motor fibers to tongue Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  7 PART D The Nervous System PowerPoint® Lecture Slide Presentation by Jerry L. Cook, Sam Houston University ESSENTIALS OF HUMAN ANATOMY & PHYSIOLOGY EIGHTH EDITION ELAINE N. MARIEB Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Spinal Nerves  There is a pair of spinal nerves at the level of each vertebrae for a total of 31 pairs  Spinal nerves are formed by the combination of the ventral and dorsal roots of the spinal cord  Spinal nerves are named for the region from which they arise Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Spinal Nerves Figure 7.22a Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Anatomy of Spinal Nerves  Spinal nerves divide soon after leaving the spinal cord  Dorsal rami – serve the skin and muscles of the posterior trunk  Ventral rami – forms a complex of networks (plexus) for the anterior Figure 7.22b Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Examples of Nerve Distribution Figure 7.23 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Autonomic Nervous System  The involuntary branch of the nervous system  Consists of only motor nerves  Divided into two divisions  Sympathetic division  Parasympathetic division Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Differences Between Somatic and Autonomic Nervous Systems  Nerves  Somatic – one motor neuron  Autonomic – preganglionic and postganglionic nerves  Effector organs  Somatic – skeletal muscle  Autonomic – smooth muscle, cardiac muscle, and glands Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Differences Between Somatic and Autonomic Nervous Systems  Nerurotransmitters  Somatic – always use acetylcholine  Autominic – use acetylcholine, epinephrine, or norepinephrine Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Comparison of Somatic and Autonomic Nervous Systems Figure 7.24 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Anatomy of the Sympathetic Division  Originates from T1 through L2  Ganglia are at the sympathetic trunk (near the spinal cord)  Short pre-ganglionic neuron and long postganglionic neuron transmit impulse from CNS to the effector  Norepinephrine and epinephrine are neurotransmitters to the effector organs Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Sympathetic Pathways Figure 7.26 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Anatomy of the Parasympathetic Division  Originates from the brain stem and S1 through S4  Terminal ganglia are at the effector organs  Always uses acetylcholine as a neurotransmitter Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Anatomy of the Autonomic Nervous System Figure 7.25 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Autonomic Functioning  Sympathetic – “fight-or-flight”  Response to unusual stimulus  Takes over to increase activities  Remember as the “E” division = exercise, excitement, emergency, and embarrassment Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Autonomic Functioning  Parasympathetic – housekeeping activites  Conserves energy  Maintains daily necessary body functions  Remember as the “D” division - digestion, defecation, and diuresis Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Development Aspects of the Nervous System  The nervous system is formed during the first month of embryonic development  Any maternal infection can have extremely harmful effects  The hypothalamus is one of the last areas of the brain to develop Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Development Aspects of the Nervous System  No more neurons are formed after birth, but growth and maturation continues for several years  The brain reaches maximum weight as a young adult Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings