Nervous System: PNS And CNS

Nervous System:PNS and CNSBiology 105Lecture 10Chapter 8

OutlineI.Central Nervous System vs Peripheral NervousSystemII. Peripheral Nervous SystemA. Somatic Nervous SystemB. Autonomic Nervous SystemIII. Autonomic Nervous SystemA. Parasympathetic Nervous SystemB. Sympathetic Nervous SystemIV. Reflex ActionsV. Central Nervous SystemA. Protection of CNSB. Spinal CordC. BrainCopyright 2009 Pearson Education, Inc.

Two Parts of the Nervous System Central Nervous System (CNS) Brain and Spinal Cord Peripheral Nervous System (PNS) Nervous tissue outside brain and spine Sensory organsCopyright 2009 Pearson Education, Inc.

Two Parts ofPeripheralNervousthe NervousSystemSystem Somatic nervous system – division of PNS thatcontrols voluntary functions. Responsible for movement, controls skeletalmuscles Autonomic nervous system – division of PNSthat controls involuntary functions. Controls cardiac and smooth muscles, andglandsCopyright 2009 Pearson Education, Inc.

Autonomic Nervous System Autonomic Nervous System is divided intotwo systems: Parasympathetic division – “rest and digest” Sympathetic division – stimulatorystress responses “flight or fight”Copyright 2009 Pearson Education, Inc.

Figure 8.1 The nervous systemCopyright 2009 Pearson Education, Inc.

PNS – Parasympathetic Nervous SystemParasympathetic Nervous System(Cranial and sacralregions of spinal eathing rateSlowsheart rateWidensbloodvesselsIncreasesdigestive activityIncreasesdigestive esStimulatesdefecationCopyright 2009 Pearson Education, Inc.Figure 8.12 (1 of 2)

Parasympathetic – Rest and Digest Constricts eye pupilsStimulates salivationSlows heart rateConstricts breathingDilates blood vesselsStimulates digestionConstricts bladderStimulates sex organsCopyright 2009 Pearson Education, Inc.

PNS – Sympathetic Nervous SystemSympathetic Nervous System(Thoracic and lumbarregions of spinal hing rateIncreasesheart rateNarrowsblood vesselsSlowsdigestive activitySlowsdigestive activityGanglionStimulates secretionof epinephrine andnorepinephrineCauses salt andwater retentionRelaxesbladder musclesInhibitsdefecationCopyright 2009 Pearson Education, Inc.Figure 8.12 (2 of 2)

Sympathetic – Fight or Flight Dilates eye pupilsInhibits salivationAccelerates heart rateFacilitates breathingStimulates secretion of epinephrine andnorepinephrineStimulates release of free glucoseInhibits digestionRelaxes bladderInhibits sex organsCopyright 2009 Pearson Education, Inc.

Reflex Actions Sometime the body requires a very fastresponse, such as reacting to a hot stove. We may not have time to send the message allthe way up to the brain to process theinformation. The spinal cord can process the informationand send a response back to the motornerves.Copyright 2009 Pearson Education, Inc.

Reflex Arc The pathway consisting of a sensory receptor,a sensory neuron, interneurons, a motorneuron, and an effector (muscle or targetorgan).Copyright 2009 Pearson Education, Inc.

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Which division of your PNS controlsvoluntary functions?1. Autonomic2. Somatic50%AutonomicCopyright 2009 Pearson Education, Inc.50%Somatic

This division of your PNS inhibits digestion:1. Parasympathetic2. Sympathetic50%PaCopyright 2009 Pearson Education, Inc.thempaSyrasympathetictic50%

This division of your PNS slows heart rateand lowers blood pressure:1. Sympathetic2. Parasympathetic50%Copyright 2009 Pearson Education, Inc.symParaSympapatthehetictic50%

Protection of the CNS The CNS consists of the brain and spinalcord, which are vulnerable structures! The CNS is protected by:1.2.3.4.Bone (skull and vertebral column)MeningesCerebrospinal fluidBlood-brain barrierCopyright 2009 Pearson Education, Inc.

Protection of the CNSThe bones of the skull andvertebral column are hardcases that protect the brainand spinal cord.The meninges are threemembranes that protectthe brain and spinal cord.Ventriclesof the brainCerebrospinal fluid cushionsthe brain and spinal cord.Copyright 2009 Pearson Education, Inc.Figure 8.2

Meninges Meninges are protective membranes(connective tissue) that cover the brain andspinal cord.There are three layers of the meninges:1. Dura mater – outer layer Tough, thick, and leathery2. Arachnoid mater – middle layer Contains thin, spider web-like extensionsconnecting to the pia mater3. Pia mater – inner layer Delicate, molded closely along thesurface of the CNSCopyright 2009 Pearson Education, Inc.

Meningitis Meningitis – inflammation of the meninges. It is caused by many forms of bacteria andviruses. If the infection spreads to the underlying braintissue, it can lead to encephalitis, aninflammation of the brain. This is a VERY serious condition!Copyright 2009 Pearson Education, Inc.

Cerebrospinal Fluid (CSF) Fluid produced in the ventricles of the brain. CSF fills: VentriclesIn-between the meningesCentral canal of the spinal cord. Functions:1. Shock absorption2. Support the weight of the brain3. Nourishment and waste removalCopyright 2009 Pearson Education, Inc.

Blood-Brain Barrier Formed by the tight junctions between thecells lining the blood vessels of the brain. Permits certain substances to enter the brain,while inhibiting others from entering. It inhibits many drugs that are not lipid-solublefrom reaching brain tissue.Copyright 2009 Pearson Education, Inc.

The innermost layer of the meninges is the:materoidmuraAracDCopyright 2009 Pearson Education, Inc.33%atemateraPi33%r33%hn1. Pia mater2. Dura mater3. Arachnoid mater

Where is CSF found?1. Central canal ofspinal cord2. Ventricles3. Between meninges4. All of the above!25%CentralCanalCopyright 2009 Pearson Education, Inc.25%25%VentriclesBetweenMeninges25%ALL

The blood-brain barrier is formed by whichkind of junctions?1. Adhesion2. Gap3. Tight33%AdhesionCopyright 2009 Pearson Education, Inc.33%Gap33%Tight

Spinal Cord Spinal cord extends from the base of the braindown the back, and transmits messagesbetween the brain and the rest of the body. There is cerebrospinal fluid located in acentral canal in the spinal cord.Copyright 2009 Pearson Education, Inc.

Spinal Cord If you look at a cross section of the spinal cordyou will see “white matter” and “gray matter”. The white matter is myelinated axons. Gray matter is mainly cell bodies andnon-myelinated axons.Copyright 2009 Pearson Education, Inc.

Spinal CordWhite matterGray matterDorsal rootDorsal-rootganglionVentral root(a) View from front of bodyCopyright 2009 Pearson Education, Inc.Pair ofspinal nervesFigure 8.11a

A Tour of the Brain Cerebrum Cerebral cortex Hippocampus Amygdala HypothalamusThalamusCerebellumBrain stem – midbrain, pons, medulla oblongata(Pineal gland and pituitary gland are in thebrain, but they are part of the endocrinesystem.)Copyright 2009 Pearson Education, Inc.

The Brain The brain is the control center of the body! Weighs less than 3 pounds, and yet isresponsible for all the unconsciousfunctioning of the body, as well as theconscious thought. The cerebral cortex of the cerebrum is thethinking, conscious part of the brain.Copyright 2009 Pearson Education, Inc.

Cerebrum

Cerebrum Contains: Cerebral cortex Hippocampus Amygdala Functions: Sensory area for touch, vision, hearing, andolfaction Motor area for voluntary movement Association area for sensation interpretation,language, thinking, decision-making, selfawareness, creativity, and memory storageCopyright 2009 Pearson Education, Inc.

Cerebrum – Cerebral Cortex Cerebral cortex – thin outer layer of thecerebrum where most of the higher thinkingand processing takes place. Contains sensory areas Prefrontal region of the cerebral cortex isresponsible for decision making Folding increases surface areaCopyright 2009 Pearson Education, Inc.

Cerebrum – Cerebral CortexCopyright 2009 Pearson Education, Inc.Figure 8.4

Cerebrum – Corpus Callosum Beneath the cortex is white matter, whichlooks white due to the high density ofmyelinated axons. Corpus callosum – band of white matter thatconnects the two cerebral hemispheres .Copyright 2009 Pearson Education, Inc.

Cerebrum and Corpus CallosumCerebrum Contains sensory areasfor skin senses, vision,hearing, olfaction Motor areas for voluntarycontrol of movement Association areas forinterpreting sensations,language, thinking,decision making,self-awareness,creativity, and storageof memoriesCorpus callosum Allows left and rightcerebral hemispheresto communicate withone anotherCopyright 2009 Pearson Education, Inc.Figure 8.3 (2 of 2)

CerebrumThe corpus callosum is aband of white matter that allowscommunication between thecerebral hemisperes.Gray matter consists ofinterneurons, cell bodies,and unmyelinated axonsthat integrate information.White matterconsists of myelinatedaxons that allowcommunication overlong distances.Copyright 2009 Pearson Education, Inc.Figure 8.5

Cerebrum Hippocampus – important in long-termmemory. Amygdala – important in remembering fearand responding to it.Copyright 2009 Pearson Education, Inc.

Memory (the Limbic dalaOlfactory bulbCopyright 2009 Pearson Education, Inc.Figure 8.8

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Thalamus Thalamus – processes sensory information(except smell) and relays it to other areas ofthe brain.Copyright 2009 Pearson Education, Inc.

Hypothalamus Functions:1. Maintains homeostasis: controls heart rate,blood pressure, breathing rate, bodytemperature2. Regulates drives such as hunger3. Controls the pituitary glandCopyright 2009 Pearson Education, Inc.

The BrainThalamus Processes all sensoryinformation(except olfaction) Relays information toappropriate higherbrain centersHypothalamus Controls heart rate,blood pressure,breathing rate, bodytemperature, food intake Is a center for emotions Serves as “masterbiological clock”Copyright 2009 Pearson Education, Inc.Figure 8.3 (2 of 2)

Cerebellum Cerebellum – maintains balance andcoordination, refines motor skills, helps learnnew motor skills.Copyright 2009 Pearson Education, Inc.

CerebellumCerebellum Coordinates sensory–motorvoluntary movement Stores memory of learnedmotor patternsCopyright 2009 Pearson Education, Inc.Figure 8.3 (1 of 2)

Brain Stem Contains: Medulla oblongata Midbrain PonsCopyright 2009 Pearson Education, Inc.

Brain Stem – Medulla Oblongata Functions: Controls many vital involuntary functionsincluding breathing, heart rate, and bloodpressureCopyright 2009 Pearson Education, Inc.

Brain Stem – Pons Functions: Assists the medulla oblongata to controlinvoluntary breathing Relays messages between the spinalcord/cerebellum, and the cerebrum, thalamus,and hypothalamusCopyright 2009 Pearson Education, Inc.

Brain Stem - Midbrain Functions: Important in voluntary muscle control Relay station for auditory and visual information Relays information between thecerebellum/spinal cord and the cerebrum Controls eye movementCopyright 2009 Pearson Education, Inc.

BrainstemThe BrainMidbrain Relays information betweenthe cerebellum or spinal cordand the cerebrum Integrates sensory inputPons A bridge between higher andlower brain centersMedulla oblongata Contains autonomic centers forheart rate and digestive activities Relays sensory information tothalamusCopyright 2009 Pearson Education, Inc.Figure 8.3 (1 of 2)

Glands Pituitary gland and pineal gland are part ofthe brain but will be covered as part of theendocrine system!Copyright 2009 Pearson Education, Inc.

Which region of the brain is the region where mostof the higher thinking and processing takes ht 2009 Pearson Education, Inc.cortex25% 25% 25% 25%AmygdalaHippocampusCerebral cortexHypothalamusla1.2.3.4.

Which region of the brain is the region important inlong-term memory?25% 25% 25% 25%amusHypralCerebocippHothalpusamdamygACopyright 2009 Pearson Education, Inc.cortexAmygdalaHippocampusCerebral cortexHypothalamusla1.2.3.4.

Which region of the brain regulates drivesincluding hunger, maintains homeostasis, controlsthe pituitary gland?25% 25% 25% 25%amusHypralCerebocippHothalpusamdamygACopyright 2009 Pearson Education, Inc.cortexAmygdalaHippocampusCerebral cortexHypothalamusla1.2.3.4.