Functions Of The Nervous System PDF

Functions of the Nervous System Functions of the Nervous System Organization of the Nervous System...

Functions of the Nervous System Functions of the Nervous System Organization of the Nervous System 1. Sensory input—gathering information 3. Motor output  Nervous system is classified based on:  To monitor changes occurring inside and outside the  A response to integrated stimuli  Structures (structural classification) body Nervous system  Changes  stimuli  The response activates muscles or glands  Activities (functional classification) 2. Integration  To process and interpret sensory input and decide Abeer Gharaibeh whether action is needed © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. Structural Classification of the Nervous Structural Classification of the Nervous Functional Classification of the Peripheral Functional Classification of the Peripheral System System Nervous System Nervous System  Central nervous system (CNS)  Peripheral nervous system (PNS)  Sensory (afferent) division  Motor (efferent) division (continued)  Organs  Nerves extending from the brain and spinal cord  Nerve fibers that carry information to the central  Two subdivisions  Brain  Spinal nerves—carry impulses to and from the spinal nervous system  Somatic nervous system  voluntary  Spinal cord cord  Somatic sensory fibers carry information from the  Consciously controls skeletal muscles  Function  Cranial nerves—carry impulses to and from the brain skin, skeletal muscles, and joints  Autonomic nervous system  involuntary  Functions  Visceral sensory fibers carry information from visceral  Automatically controls smooth and cardiac muscles  Integration; command center  Serve as communication lines among sensory organs, organs and glands  Interpret incoming sensory information the brain and spinal cord, and glands or muscles  Motor (efferent) division  Further divided into the sympathetic and  Issues outgoing instructions parasympathetic nervous systems  Nerve fibers that carry impulses away from the central nervous system organs © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. Central Nervous System (CNS) Regions of the Brain Regions of the Brain: Cerebrum Regions of the Brain: Cerebrum  CNS develops from the embryonic neural tube  Cerebral hemispheres (cerebrum)  Cerebral hemispheres are paired (left & right)  Lobes of the cerebrum  The neural tube becomes the brain and spinal cord  Diencephalon superior parts of the brain  Fissures (deep grooves) divide the cerebrum into  The opening of the neural tube becomes the  Brain stem  Includes more than half of the brain mass lobes ventricles  Cerebellum  The surface is made of ridges (gyri) and grooves  Surface lobes of the cerebrum  Four chambers within the brain (sulci)  Frontal lobe  Filled with cerebrospinal fluid  Three main regions of cerebral hemisphere  Parietal lobe 1.Cortex (gray matter)  Occipital lobe 2.White matter  Temporal lobe 3.Basal nuclei (deep pockets of gray matter) © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. Regions of the Brain: Cerebrum Regions of the Brain: Cerebrum Regions of the Brain: Cerebrum Regions of the Brain: Cerebrum  Cerebral areas involved in special senses  Specialized areas of the cerebrum  Broca’s area  Layers of the cerebrum  Visual area (occipital lobe)  Primary motor area  Involved in our ability to speak  Gray matter—outer layer in the cerebral cortex;  Auditory area (temporal lobe)  Sends impulses to skeletal muscles  Usually in left hemisphere composed mostly of neuron cell bodies  Olfactory area (temporal lobe)  Located in frontal lobe  Other specialized areas  White matter—fiber tracts deep to the gray matter  Motor neurons form corticospinal (pyramidal) tract,  Anterior and posterior association areas  Corpus callosum connects hemispheres which descends to spinal cord  Basal nuclei (ganglia)—islands of gray matter  Speech area  Motor homunculus is a spatial map buried within the white matter © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited.  Regions of the Brain: Diencephalon Regions of the Brain: Diencephalon Regions of the Brain: Diencephalon Regions of the Brain: Diencephalon  Sits on top of the brain stem  Thalamus  Hypothalamus  Epithalamus  Enclosed by the cerebral hemispheres  Surrounds the third ventricle  Under the thalamus  Forms the roof of the third ventricle  Made of three parts:  The relay station for sensory impulses  Important autonomic nervous system center  Houses the pineal body (an endocrine gland) 1. Thalamus  Transfers impulses to the correct part of the cortex  Helps regulate body temperature  Includes the choroid plexus—forms cerebrospinal 2. Hypothalamus for localization and interpretation  Controls water balance fluid  Regulates metabolism 3. Epithalamus  Houses the limbic center for emotions  Regulates the nearby pituitary gland  Houses mammillary bodies for olfaction (smell) © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. Regions of the Brain: Brain Stem Regions of the Brain: Brain Stem Regions of the Brain: Brain Stem Regions of the Brain: Brain Stem  Attaches to the spinal cord  Midbrain  Pons  Medulla oblongata  Parts of the brain stem  Composed mostly of tracts of nerve fibers  The bulging center part of the brain stem  The lowest part of the brain stem  Midbrain  Two bulging fiber tracts, cerebral peduncles, convey  Mostly composed of fiber tracts  Merges into the spinal cord  Pons ascending and descending impulses  Includes nuclei involved in the control of breathing  Includes important fiber tracts  Medulla oblongata  Four rounded protrusions, corpora quadrigemina,  Contains important control centers visual and auditory reflex centers  Heart rate control  Blood pressure regulation  Breathing  Swallowing  Vomiting © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. Regions of the Brain: Cerebellum Protection of the Central Nervous System Meninges Meninges  Two hemispheres with convoluted surfaces  Scalp and skin  Dura mater  Arachnoid layer  Controls balance and equilibrium  Skull and vertebral column  Tough outermost layer  Middle layer  Provides precise timing for skeletal muscle activity  Meninges  Double-layered external covering  Weblike extensions span the subarachnoid space and coordination of body movements  Cerebrospinal fluid (CSF)  Periosteum—attached to inner surface of the skull  Arachnoid villi reabsorb cerebrospinal fluid  Meningeal layer—outer covering of the brain  Pia mater  Blood-brain barrier  Folds inward in several areas  Internal layer  Falx cerebri  Clings to the surface of the brain  Tentorium cerebelli © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. Cerebrospinal Fluid (CSF) Cerebrospinal Fluid (CSF) Pathway of Flow Hydrocephalus in a Newborn Blood-Brain Barrier  Similar to blood plasma composition 1. CSF is produced by the choroid plexus of each  Hydrocephalus  Includes the least permeable capillaries of the body  Formed by the choroid plexus ventricle.  CSF accumulates and exerts pressure on the brain if  Excludes many potentially harmful substances  Choroid plexuses–capillaries in the ventricles of the 2. CSF flows through the ventricles and into the not allowed to drain  Useless as a barrier against some substances brain subarachnoid space via the median and lateral  Possible in an infant because the skull bones have  Fats and fat-soluble molecules  Forms a watery cushion to protect the brain apertures. Some CSF flows through the central not yet fused  Respiratory gases  Circulated in arachnoid space, ventricles, and canal of the spinal cord.  In adults, this situation results in brain damage  Alcohol central canal of the spinal cord 3. CSF flows through the subarachnoid space.  Nicotine 4. CSF is absorbed into the dural venous sinuses via  Anesthesia the arachnoid villi. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited.  Blood-Brain Barrier Spinal Cord Peripheral Nervous System (PNS) PNS: Structure of a Nerve  Water-soluble items that can travel through barrier:  Extends from the foramen magnum of the skull to  PNS consists of nerves and ganglia outside the  Endoneurium surrounds each fiber  Water the first or second lumbar vertebra central nervous system  Groups of fibers are bound into fascicles by  Glucose  Provides a two-way conduction pathway to and from  Nerve  bundle of neuron fibers perineurium  Essential amino acids the brain  Neuron fibers are bundled by connective tissue  Fascicles are bound together by epineurium  Items prevented from passing through:  31 pairs of spinal nerves arise from the spinal cord  Metabolic wastes  Ends around vertebra L1 or L2  Most drugs  Cauda equina is a collection of spinal nerves at the  Nonessential amino acids inferior end  Potassium ions © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. PNS: Classification of Nerves PNS: Cranial Nerves PNS: Cranial Nerves Mnemonic Device PNS: Spinal Nerves  Mixed nerves  12 pairs of nerves that mostly serve the head and  Oh – Olfactory  There is a pair of spinal nerves at the level of each  Both sensory and motor fibers neck  Oh – Optic vertebra, for a total of 31 pairs  Only the pair of vagus nerves extends to thoracic  Oh – Oculomotor  Formed by the combination of the ventral and dorsal  Sensory (afferent) nerves and abdominal cavities  To – Trochlear roots of the spinal cord  Carry impulses toward the CNS  Touch – Trigeminal  Motor (efferent) nerves  Most are mixed nerves, but three are sensory only:  Named for the region from which they arise  And – Abducens  Carry impulses away from the CNS 1. Optic  Feel – Facial 2. Olfactory  Very – Vestibulocochlear 3. Vestibulocochlear  Green – Glossopharyngeal  Vegetables – Vagus  A – Accessory  H – Hypoglossal © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. PNS: Spinal Nerve Plexuses PNS: Autonomic Nervous System PNS: Autonomic Functioning PNS: Autonomic Functioning  Plexus–networks of nerves serving motor and  Motor subdivision of the PNS  Sympathetic—“fight or flight” division  Parasympathetic—“housekeeping” activites sensory needs of the limbs  Consists only of motor nerves  Response to unusual stimulus  Conserves energy  Form from ventral rami of spinal nerves in the  Also known as the involuntary nervous system  Takes over to increase activities  Maintains daily necessary body functions cervical, lumbar, and sacral regions  Regulates activities of cardiac and smooth muscles  Remember as the “E” division:  Remember as the “D” division  Four plexuses: and glands  Exercise  Digestion 1. Cervical  Two subdivisions:  Excitement  Defecation 2. Brachial 1.Sympathetic division  Emergency  Diuresis 3. Lumbar 2.Parasympathetic division  Embarrassment 4. Sacral © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. Developmental Aspects of the Nervous Developmental Aspects of the Nervous Developmental Aspects of the Nervous Developmental Aspects of the Nervous System System System System  The nervous system is formed during the first month  Severe congenital brain diseases include:  Premature babies have trouble regulating body  Brain growth ends in young adulthood. Neurons die of embryonic development  Cerebral palsy temperature because the hypothalamus is one of throughout life and are not replaced; thus, brain  Any maternal infection can have extremely harmful  Anencephaly the last brain areas to mature prenatally. mass declines with age. effects  Hydrocephalus  Development of motor control indicates the  Healthy aged people maintain nearly optimal  Oxygen deprivation destroys brain cells  Spina bifida progressive myelination and maturation of a child’s intellectual function.  The hypothalamus is one of the last areas of the nervous system.  Disease—particularly cardiovascular disease—is brain to develop the major cause of declining mental function with age. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited. © 2015 Pearson Education, Limited.