EXSC%224:%Week%of%1/9/17%Textbook%Notes%Ch.%11.1%&%11.2%11.1#The#nervous#system#receives,#integrates,#and#responds#to#information#• Nervous#system#has#3#functions#1. Sensory#input:#sensory#receptors#detect#changes#inside#and#outside#the#body#2. Integration:#processing#of#the#sensory#input#to#decide#what#to#do#3. Motor#output:#nervous#system#activates#effector#organs#(muscles#and#glands)#to#cause#a#response#o Ex:#see#a#red#light#while#driving#(sensory#input),#nervous#system#recognizes#what#this#info#means#and#what#to#do#(integration),#foot#hits#the#brake#(motor#output)#• Central#nervous#system#(CNS)#o Brain#and#spinal#cord#o Control#center#of#the#nervous#system#o Interprets#sensory#information#and#dictates#motor#output#• Peripheral#nervous#system#(PNS)#o Consists#of#nerves#that#extend#from#the#brain#and#spinal#cord#§ Spinal#nerves:#carry#impulses#to#and#from#spinal#cord#§ Cranial#nerves:#carry#impulses#to#and#from#the#brain#o Contains#ganglia:#collections#of#neuron#cell#bodies#o Two#divisions:#afferent#(sensory)#and#efferent#(motor)#§ Afferent#• Nerve#fibers#that#carry#impulses#to#the#central#nervous#system#from#sensory#receptors#• Somatic#sensory#fibers#convey#impulses#from#skin,#skeletal#muscles,#and#joints#• Visceral#sensory#fibers#convey#impulses#from#the#visceral#organs#• Keeps#the#CNS#aware#of#what#is#going#on#in#and#out#of#the#body#§ Efferent#• Transmits#impulses#from#the#CNS#to#effector#organs#• Has#2#parts#o Somatic#nervous#system#§ Somatic#nerve#fibers#that#conduct#impulses#from#the#CNS#to#skeletal#muscles#§ Voluntary#o Autonomic#nervous#system#§ Visceral#motor#nerve#fibers#that#regulate#activity#of#smooth#and#cardiac#muscles#and#glands#§ Involuntary#§ Has#2#subdivisions#• Sympathetic:#stimulates#• Parasympathetic:#inhibits#11.2#Neuroglia#(glial#cells)#support#and#maintain#neurons#• Neuroglia#(glial#cells)#o Cells#in#the#nervous#system#that#associate#closely#with#neurons#o 6#types#(4#in#CNS#and#2#in#PNS)#• glial#cells#in#the#CNS#o astrocytes:#brace#and#support#o microglial#cells:#initiates#immune#response#o ependymal#cells:#line#cavities#o oligodendrocytes:#produce#myelin#• glial#cells#in#the#PNS#o satellite#cells:#brace#and#support#o schwann#cells:#produce#myelin#%Lecture%1/10%Notes%4#essential#concepts#for#physiology#1. Physiology#uses#gradients#2. Negative#feedback#systems#are#essential#to#homeostasis#3. Principle#of#complementarity#4. Regulate#protein#function#by#regulating#its#shape#The#nervous#system#does#3#things#1. Sensory#input:#information#is#gathered#by#sensory#receptors#about#internal#and#external#changes#and#sent#to#the#CNS#2. Integration:#interpretation#of#sensory#input#3. Motor#output:#activation#of#effector#organs#(muscles#and#glands)#produces#a#response#Nervous%System%Central%Nervous%System%(CNS)%*Brain#and#spinal#cord#*Integrative#and#control#centers#Peripheral%Nervous%System%(PNS)%*Cranial#and#spinal#nerves#*Nerves#only#exist#here#*Communication#lines#between#CNS#and#rest#of#body################Afferent%(sensory%division)%*#Somatic#and#visceral#sensory#nerve#fibers#*Conducts#impulses#from#receptors#to#the#CNS#Efferent%(motor%division)%*Motor#nerve#fibers#*Conducts#impulses#from#CNS#to#effectors#Somatic%*Voluntary#*Conducts#CNS#to#skeletal#muscle#Autonomic%*involuntary#*conducts#impulses#from#CNS#to#cardiac#and#smooth#muscle#and#glands####Sympathetic%*mobilizes#body#during#activity##Para-sympathetic%*conserves#energy#*rest#and#digest#Histology#of#nervous#tissue#• 2#main#cells#in#the#nervous#system:#Neuroglia#(glial#cells)#and#neurons#o Neuroglia:#supporting#cells#to#neurons#§ Glial#cells#in#CNS#• Astrocytes#o Most#abundant,#versatile,#lots#of#branches#o Cling#to#neurons,#synaptic#endings,#and#capillaries#o Support#and#brace#neurons#(hold#them#in#place)#o Help#determine#capillary#permeability#• Microglia#o Small,#ovoid#cells#with#thorny#processes#o 1st#line#of#defense#o alerts#immune#system#to#any#problems#o migrate#toward#injured#neurons#o phagocytize#• ependymal#cells#o line#cavities#of#brain#and#spinal#column#o separate#CNS#interstitial#fluid#from#cerebrospinal#fluid#o produce#cerebrospinal#fluid#at#choroid#plexuses#o water#tight#seal#o may#be#ciliated#to#help#with#circulation#of#cerebrospinal#fluid#• oligodendrocytes#o make#myelin#o processes#wrap#around#axons#in#CNS#to#insulate#o myelin#speeds#up#transmission#o multiple#sclerosis:#demyelination#in#CNS#§ Glial#cells#in#PNS#• Satellite#cells#o Surround#neuron#cell#bodies#o Same#function#as#astrocytes:#support#and#brace#neurons#• Schwann#cells#o Surround#nerve#fibers#to#form#myelin#sheath#o Vital#to#regeneration#of#damaged#peripheral#nerve#fibers#o Neurons#§ Primary#cells#in#the#nervous#system#§ Special#characteristics#• Long#lived#• Amitotic#with#few#exceptions#• High#metabolic#rate:#dependent#on#supply#of#O2#and#glucose#• Plasma#membrane#functions#in#electrical#signaling#and#cell#to#cell#interactions#(at#the#synapses)#§ Have#high#energy#costs:#20%#of#energy#expenditure#when#at#rest#§ Neuron#types:#multipolar#(efferent#neurons),#bipolar#(rare,#associated#with#eyes),#unipolar#(afferent#neurons)##Textbook%Notes%Ch.%11.3%&%11.4%11.3#Neurons#are#the#structural#units#of#the#nervous#system#• Characteristics#o Typically#large#o Highly#specialized#cells#o Extreme#longevity:#with#good#nutrition,#they#last#a#lifetime#o Amitotic:#can’t#divide#o High#metabolic#rate:#use#lots#of#oxygen#and#glucose#• Neuron#cell#body#(soma)#o Biosynthetic#center#of#the#neuron:#produces#all#the#necessary#proteins#and#chemicals#o Has#a#really#well-developed#Rough#ER#(called#Nissl%bodies)#and#Golgi#apparatus#for#producing#and#packaging#all#the#necessary#neurotransmitters#that#are#released#following#an#action#potential#o Most#neuron#cell#bodies#are#in#the#CNS#§ Protected#here#by#the#skull#and#vertebral#column#§ Clusters#of#cell#bodies#in#the#CNS#are#called#nuclei#(called#ganglia#in#the#PNS)#• Neuron#processes:#arm-like#extensions#from#the#cell#body#o Include#dendrites#and#axons#o PNS#consists#mostly#of#neuron#processes#o Dendrites#§ Diffusely#branching#extensions#§ Has#the#same#organelles#as#the#cell#body#§ Main#receptive/input#region#§ Large#surface#area#for#receiving#signals#from#other#neurons#§ Send#signals#to#the#cell#body,#typically#as#graded#potentials#o Axon#§ Structure#• Each#neuron#has#only#one#•