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Human Physiology Notes 2/1 - 2/12

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Human Physiology Notes 2/1 - 2/12 BIOL 3160

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These notes cover the initial topics Dr. McNutt began to cover the week of our test (2/3) and all of the notes covered up until last week (2/12). Chapter 8 and 9 and the first 9 slides for chapter ...
Human Physiology
Dr. Tamara McNutt-Scott
Class Notes
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Abigail Towe

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This 15 page Class Notes was uploaded by MBattito on Monday February 15, 2016. The Class Notes belongs to BIOL 3160 at Clemson University taught by Dr. Tamara McNutt-Scott in Fall 2015. Since its upload, it has received 82 views. For similar materials see Human Physiology in Biological Sciences at Clemson University.


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Date Created: 02/15/16
Chapter  8:  Central  Nervous  System     The  central  nervous  system  (CNS)  is  comprised  of  brain  and  spinal  cord   • Functions  to:     o Receive  input  information  from  sesnsory  neurons   o Direct  activity  of  motor  neurons  that  innervate  muscles  and  glands   o Association,  or  interneurons,  within  brain  and  spinal  cord  serve  to   “associate”  appropriate  motor  responses  with  sensory  stimuli,  thus   maintaining  homeostasis   During  development:   • Ectoderm:  embryonic  tissue  layer  on  the  surface  of  an  early  embryo     o Eventually  will  form  the  epidermis  of  the  skin   • A  groove  develops  in  the  ectoderm  along  the  dorsal  midline  of  the  embryo’s   body   o Groove  deepens  and  forms  the  neural  tubeà  neural  tube  becomes  the   CNS   • Neural  crest:  part  of  the  ectoderm  where  the  fusion  of  the  neural  tube  occurs     o Located  between  the  neural  tube  and  the  surface  ectoderm   o Neural  crest  (among  other  structures)  becomes  the  ganglia  of  the   peripheral  nervous  system     • Anterior  portion  of  neural  tube  becomes  brain,  folds  form  3  distinct  regions   o Forebrain  (prosencephalon)   § At  fifth  week  of  development  differentiates  to  form   telencephalon  and  diencephalon   § Telencephalon  grows  disproportionately  in  humans  à  forms   the  two  enormous  cerebral  hemispheres   o Midbrain  (mesencephalon)   o Hindbrain  (rhombencephalon)   § At  fifth  week  of  development  differentiates  to  form   metencephalon  and  myelencephalon     • Ventricles:  cavities  that  maintain  “hollow”  morphology  à  filled  with   cerebrospinal  fluid   o Central  canal:  cavity  in  the  spinal  cord;  also  filled  with  cerebrospinal   fluid   § Cerebrospinal  fluid:  formed  by  choroid  plexuses   • Constant  composition   • Slightly  hypertonic   • Differs  from  plasma  in  its  concentrations  of  various  ions   • Moves  by  pulsations  in  the  choroid  plexuses     CNS  comprised  of  gray  and  white  matter   • Grey  matter:  contains  neuron  cell  bodies  and  dendrites   o Found  in  the  cortex  of  the  brain  and  deeper  within  the  brain  in   aggregations  known  as  nuclei     • White  matter:  myelinated  axon  tracts     o Underlie  the  cortex  and  surround  the  nuclei     Brain:   • 3-­‐35  lbs   • receives  about  15%  total  blood  flow  to  body  per  minute  à  due  to  high   metabolic  requirements   • Involvement  in  learning  and  memory  –  permits  behavior  to  be  modified  by   experience   o Benefits  survival     • Along  with  perceptions,  emotions  and  self-­‐awareness  forms  basis  oc   consciousness   • Neural  stem  cells  develop  into  neurons  and  glial  cells   o Neurogenesis:  formation  of  new  neurons  from  neural  stem  cells;   observed  in  2  locations:   § Subventricular  zone:  thin  layer  adjacent  to  the  ependymaa  that   lines  the  lateral  ventricles   • In  mammals  (other  than  humans)  the  neurons   generated  here  migrate  to  the  olfactory  bulbs  à   involved  in  sense  of  smell     • In  humans:  neurons  generated  here  migrate  to  the   striatum  à  regulates  motor  control  and  cognitive   functions   § Subgranular  zone:  in  the  hippocampus   • Form  interneurons  that  function  within  the   hippocampus  to  aid  learning  and  memory     • Brain  creations:   o Not  a  “singular  event”       Cerebrum   • Largest  portion  of  the  brain   • Region  primarily  responsible  for  higher  brain  functions   • Divided  into  left  and  right  hemispheres   o Connected  internally  via  large  fiber  tract  à  corpus  callosum     § Corpus  callosum:  major  tract  of  axons  that  functionally   interconnects  the  hemispheres   • Cerebral  cortex   § 2-­‐4mm  of  gray  matter  form  the  outer  surface  –  underlying   white  matter   o Anatomic  construction  increases  area  for  neurons  but  does  not   increase  volumeà  convolutions   § Gyri:  elevated  folds  of  convolutions   § Sulci:  depressed  grooves  of  convolutions   o Most  complex  integrating  area  of  nervous  system     5  lobes  of  the  cerebrum  and  their  functions   • Frontal:  voluntary  motor  control  of  skeletal  muscles;  personality;  higher   intellectual  processes;  verbal  communication   • Parietal:  somatesthetic  interpretation;  understanding  speech  and   formulating  words  to  express  thoughts  and  emotions;  interpretation  of   textures  and  shapes     • Temporal:  interpretation  of  auditory  sensations;  storage  (memory)  of   auditory  and  visual  experiences     • Occipital:  integration  of  movements  in  focusing  the  eye;  correlation  of  visual   images  with  previous  visual  experiences  and  other  sensory  stimuli;   conscious  perception  of  vision   • Insula:  memory;  sensory  (principally  pain)  and  visceral  integration   • Cortex  is  mapped  by  regions  of  body  –  somatotopy   o Note  that  body  part  size  does  not  correspond  with  amount  of  cortical   area  used  à  body  regions  with  the  highest  densities  of  receptors  are   represented  by  the  largest  areas  of  the  sensory  cortex  and  the  body   regions  with  the  greatest  number  of  motor  innervations  are   represented  by  the  largest  areas  of  motor  cortex   § The  hands  and  face  are  served  by  a  larger  area  than  the  rest  of   the  body       Electroencephalogram   • Synaptic  potentials  produced  by  cell  bodies  and  dendrites  in  cerebral  cortex   create  electrical  currents  that  can  be  measured  by  electrodes  placed  on  the   scalp  à  termed  electroencephalogram  (EEG)   • Deviations  from  normal  EEG  patterns  can  be  used  clinically  to  diagnose   epilepsy  and  other  abnormal  states   o Abnormal  synchronized  discharges  of  cerebral  neuron   o Electrical  storm  within  a  short  circuit,  occurs  at  small  spot  within   brain  –  focus  –  causes  waves  of  electrical  activity  to  spread   throughout  brain   • Absence  of  EEG  signifies  brain  death   • 4  type  of  EEG  patterns:   o Alpha  waves:  best  recorded  from  parietal  and  occipital  regions  while  a   person  is  awake  and  relaxed  with  eyes  closed   § Rhythmic  oscillations  of  10-­‐12  cycles/second   o Beta  waves:  strongest  near  frontal  lobes   § Evoked  activity:  produced  by  visual  stimuli  and  mental  activity     § 13-­‐25  cycles/second   o Theta  waves:  emitted  from  temporal  and  occipital  lobes   § Common  in  infants  and  sleeping  adults   § Increase  in  awake  adults  during  tasks  the  require  attention  and   memory,  sleep  deprivation,  and  severe  emotional  stress   § 5-­‐8cycles/seconds   o Delta  waves:  emitted  in  a  general  pattern  from  the  cerebral  cortex   § Common  during  sleeping  adults  and  awake  infants   § 1-­‐5cycles/second   § Presence  in  an  awake  adult  indicates  brain  damage   Sleep   • EEG  patterns  change  with  sleep   o REM  sleep:  when  you  dream   § Theta  waves   § Limbic  system  is  active  during  REM  sleep   § Higher  total  brain  metabolism  and  higher  blood  flow   § Irregular  breathing   o Non-­‐REM  (NREM)  sleep:  remainder  of  time  during  sleep   § Resting  sleep   § Decreased  energy  metabolism  and  blood  flow   § Regular  breathing  and  heart  rate   § Subjects  allowed  to  have  NREM  sleep  after  a  learning  trial   displayed  improved  performance  to  those  not  allowed  NREM   sleep   § 4  stages  of  NREMà  stages  3-­‐4  are  known  as  slow-­‐wave  sleep   • delta  waves   • Observe  cycles  with  subject  going  through  stages  of  NREM  seep,  then  ascend   back  through  to  REM,  followed  by  stages  of  NREM   o Cycle  ~  90  minutes   o 4-­‐5  REM  to  NREM  cycles  per  night   o Typically  wake  up  from  REM  sleep   Basal  Nuclei   • Masses  of  gray  matter  deep  within  white  matter  of  cerebrum  composed  of   neuron  cell  bodies     • Play  important  role  in  movement  and  posture  as  well  as  complex  aspects  of   behavior   • Corpus  striatum:  most  prominent  basal  nuclei   o Composed  of  the  caudate  and  lentiform  (consisting  of  putamen  and   globus  pallidus  portions)  nuclei   o Function  in  the  control  of  voluntary  movement   • Substantia  nigra  and  subthalamic  nuclei   o Functionally  associated  with  basal  nuclei   • Motor  circuit:     o Motor  cortex  sends  signals  to  basal  nuclei   o Putamen  in  basal  nuclei  sends  signals  to  other  BN  areas   o GP  and  SN  send  signals  to  thalamus   o Thalamus  then  sends  signals  to  motor  cortex   o Allows  intended  movements  while  inhibiting  unintended  movements   Cerebral/Hemispheric  lateralization   • Cerebral  hemispheres  appear  symmetrical,  but  each  has  anatomic  chemical   and  functional  specializations   • Information  entering  brain  decussates  (crosses  over)  à  thus  the  right  side  of   the  brain  controls  the  left  side  of  the  body  and  vise  versa   o Communication  via  corpus  callosum  keeps  each  hemisphere   appraised  of  “total”  body  function   • Through  experimentation,  found  that  each  hemisphere  is  good  at  certain   categories  of  tasks  and  poor  at  others   o Lead  to  concept  of  cerebral  dominance   § Handedness:  people  generally  have  a  greater  motor   competence  with  one  hand  than  with  the  other   • Right-­‐handed  à  left  hemisphere  dominant   o Hemispheres  function  complementary  to  each  other  (neither   subordinate)   o Cerebral  lateralization:  specialization  of  function  in  one  hemisphere   à  now  preferred  over  cerebral  dominance   • Speculate  that  creative  ability  may  be  related  to  interaction  of  information   between  hemispheres   o Proportion  of  left-­‐handed  art  students  is  much  higher  than  right-­‐ handed   Language   • Potential  for  development  of  language  specific  mechanism  in  left  hemisphere   is  present  at  birth,  yet  assignment  is  flexible  in  early  years  of  life  à  after,   success  rates  decline   • Language  is  a  complex  code  that  includes  the  acts  of  listening,  seeing,  reading   and  speaking  with  each  aspect  of  language  dealt  with  by  different  regions   • Knowledge  gained  through  study  of  aphasias:  speech  and  language  disorders   caused  by  damage  to  the  brain  through  injury  or  stroke   • Key  regions  of  particular  importance  in  the  production  of  aphasia:  Broca’s   area  and  Wernicke’s  area   o Broca’s  Aphasia:     § Weakness  in  the  right  arm  and  right  side  of  face   § Those  affected  are  reluctant  to  speak   § Speech  is  slow  and  poorly  articulated   § Comprehension  of  speech  is  unimpaired   § Not  due  to  motor  control  à  tongue,  lips,  larynx,  etc.  are   unaffected     o Wernicke’s  Aphasia:     § Results  in  speech  that  is  rapid  and  fluid  but  without  meaning   à  word  salad   § Language  comprehension  is  destroyed  –  cannot  understand   spoken  or  written  language     § Wernicke’s  area:  concept  of  words  originates  here   • Arcuate  fasciculus:  fiber  tract  that  communicates  between  Broca’s  area  and   Wernicke’s  area   o To  speak  intelligibly,  the  concept  of  words  originated  in  Wernicke’s   area  must  be  communicated  to  Broca’s  area   o Broca’s  area  sends  fibers  to  the  motor  cortex  à  directly  controls   musculature  of  speech   o Conduction  aphasia:  damage  to  the  arcuate  fasciculus     § Produces  fluent  but  nonsensical  speech   • Angular  gyrus:  located  at  the  junction  of  the  parietal,  temporal  and  occipital   lobe   o Believed  to  be  the  center  for  the  integration  of  auditory,  visual  and   somatesthetic  information   o Damage  to  it  produces  aphasias—suggests  it  projects  into  Wernicke’s   area   PET  scans   • Increased  blood  flow  to  specific  lobes  of  brain  during  various  language-­‐based   activities     Limbic  System  and  Emotion   • Hypothalamus  and  limbic  system  are  important  brain  regions  for  neural   element  of  emotional  states   • Limbic  system:  consists  of  a  group  of  forebrain  nuclei  and  fiber  tracts  that  for   a  ring  around  the  brain  stem   o Initially  called  “smell  brain”  because  it  is  involved  in  the  central   processing  of  olfactory  informationà  primary  function  in  lower   vertebrates   o The  center  for  emotional  drives  and  derived  early  in  course  of   vertebrate  evolution     o Few  synaptic  connections  between  the  cerebral  cortex  and  limbic   system  –  explains  why  we  have  so  little  conscious  control  over  our   emotions   • Involved  in:     o Aggression:  stimulation  of  certain  areas  of  the  amygdala  and   hypothalamus  produce  rage  and  aggression   o Fear:  amygdala  is  needed  for  fear  conditioning   o Feeding:  hypothalamus  contains  both  feeding  center  and  satiety   center   § Stimulation  of  the  feeding  center  results  in  overeating   § Stimulation  of  the  satiety  center  will  stop  feeding  behavior   o Sex:  limbic  system  and  hypothalamus  important  in  regulation  of  sex   drive  and  behavior   § In  lower  animals:  cerebral  cortex  is  important  in  sex  drive   § In  humans:  cerebrum  is  more  important  in  sex  drive   o Goal-­‐oriented  behavior:  center  of  reward/punishment  system   • Papez  circuit:  Closed  circuit  that  information  flows  through  between  the   limbic  system  and  the  thalamus  and  hypothalamus   o Hippocampal/mammillothalamic  tract   o Found  to  be  involved  in  consolidation  of  memories  à  “passes  through   circuit”     Learning  and  Memory   • Learning:  acquisition  and  stoage  of  information  as  a  consequence  of   experience   o Measured  by  increase  in  likelihood  of  a  particular  behavioral  response   to  a  stimulus   o Rewards/punishments  crucial  ingredients  in  learning   • Memory:  relatively  permanent  storage  form  of  learned  information   o Not  single,  unitary  phenomenon   § Bra  processes,  stores  and  retrieves  information  in  different   ways  to  suit  different  needs   Memory   • Several  different  brain  regions  involved  with  storage  and  retrieval     o Amnesia:  loss  of  memory   § Result  with  damage  to  several  different  areas     § Suggests  the  presence  of  several  different  systems  of   information  storage  available  in  brain   • Different  categories     o Short-­‐term  or  working  memory:   § Registers  and  retains  incoming  information  for  a  short  time   • Retention:  seconds-­‐minutes   § New  memories  not  instantly  permanent  and  susceptible  to   modification   • Require  protein  synthesis  before  becoming  stable   § Stored  differently  dependent  on  type  of  information  to  be   stored  –  involves  prefrontal  lobe   o Long  Term  memory:   § Store  for  days  to  years   § Depends  on  the  synthesis  of  mRNA  and  protein   § Memory  consolidation:  conversion  of  short-­‐term  memories,   recalled  at  a  later  time   • Requires  the  activation  of  genes,  the  production  of  new   proteins,  and  the  formation  of  new  synapses     § Classified  as:     • Non-­‐declarative  (implicit)  memory:  memory  of  simple   skills  and  conditions  (ex.  How  to  tie  a  shoelace)   • Declarative  (explicit)  memory:  retention  and  recall  of   conscious  experiences  that  can  be  verbalized;  people   with  amnesia  have  impaired  declarative  memory   o Sematic  (fact)  memory:  remembering  the  names   of  the  bones   o Episodic  (event)  memory:  remembering  the   experience  of  taking  a  practical  exam  on  the   skeletal  system   • Removal  of  the  left  medial  temporal  lobe  impairs  the  consolidation  of  verbal   memories  while  removal  of  the  right  medial  temporal  lobe  impairs  the   consolidation  of  nonverbal  memories   • Hippocampus  appears  to  be  important  component  of  memory  system   o MRIs  reveal  that  the  hippocampus  is  often  shrunken  in  living  amnesia   patients   • Emotions  influence  and  strengthen/hinder  memory  formation   o Amygdala  improves  memory  when  there  is  an  emotional  content   (fear)   • Stress  hinders  memory  formation   o Reduces  ability  of  hippocampus  to  form  memories   § Mechanism  unknown  but  area  targeted  (hippocampus  and   amygdala)  due  to  presence  of  receptors  for  stress   • Inferior  temporal  lobes:  appear  to  be  sites  for  the  storage  of  long-­‐term  visual   memories   o Medial  regions  cannot  be  site  of  storage  because  destruction  of  these   area  in  patients  treated  for  epilepsy  did  not  destroy  the  memory  of   events  prior   Synaptic  changes:     § Short-­‐term  memory  involves  establishment  of  recurrent/reverberating   circuits   o Where  neurons  synapse  with  each  other  to  form  a  circular  path  à  last   neuron  to  be  activated  then  stimulates  the  first  neuron   o The  circuits  are  the  neuronal  basis  of  working  memory     § Consolidation  involves  permanent  changes  to  the  chemical  structure  of   neurons  and  their  synapses  with  protein  synthesis  being  required   o Long-­‐Term  Potentiation  (LTP)   § Type  of  synaptic  learning   § Mechanism  couples  frequent  activity  across  synapse  with   lasting  changes  in  signal  strength  across  the  synapse   § Stimulation  at  high  frequency  exhibit  subsequent  increased   excitability     Long-­‐Term  Potentiation:   § Induced  by  the  activation  of  NMDA  receptors  for  glutamate   § At  resting  membrane  potential  the  pore  is  blocked  by  Magnesiumà  does  not   allow  entry  of  potassium  even  if  glutamate  is  present   § To  allow  activation  of  NMDA  receptors,  the  membrane  must  become  partially   depolarized  to  make  the  magnesium  leave  the  pore   o The  depolarization  could  be  caused  by  glutamate  binding  to  the  AMPA   receptor   § When  glutamate  can  bind  to  its  NMDA  receptor,  the  NMDA  channel  opens   allowing  calcium  to  diffuse  into  the  cell   § The  calcium  binds  to  calmodulin  à  activates  CaMKII  enzyme   o The  CaMKII  moves  to  the  synapse  and  phosphorylates  proteins  that   allow  more  AMPA  receptors  for  glutamate  to  be  inserted  into  the   postsynaptic  membrane  and  increase  the  ion  conductance  of  each   AMPA  channel   § Specific  to  that  stimulated  synapse   § Result:  synaptic  transmission  of  that  synapse  is  strengthened   so  that  a  given  amount  of  glutamate  produces  a  greater   postsynaptic  depolarization  à  EPSP     § The  rise  in  the  intracellular  calcium  concentration  also  causes  longer-­‐term   changes  in  the  postsynaptic  neuron   o The  long  term  changes  activate  CREB  and  other  epigenetic  changes   that  contribute  to  long-­‐term  memory     § Most  ESPS  are  produced  on  dendritic  spines  à  LTP  induces  dendritic  spines   to  enlarge  and  change  shape   o LTD  dendritic  spines  are  observed  to  shrink  or  disappear   Neural  stem  cells   § Found  in  hippocampus   § Suggest  that  neurogenesis  may  be  involved  in  earning  and  memory   § Depolarization-­‐induced  suppression  of  inhibition  endocannabinoid   § Neurogenesis  occurs  in  subgranular  zone   Diencephalon:     § Represents  structures  around  the  third  ventricle  and  are  completely   surrounded  by  the  cerebral  hemispheres     § Comprised  of:   o Thalamus:  primarily  relay  center  through  which  all  sensory   information  (except  smell)  passes  to  cerebrum   o Epithalamus:     § Contains  choroid  plexus:  where  cerebral  spinal  fluid  is  formed   § Contains  pineal  gland:  secretes  melatonin  to  regulate  circadian   rhythms     o Hypothalamus:  collection  of  nuclei  that  are  involved  in  a  variety  of   homeostatic  processes   Brainstem   § Comprised  of  midbrain,  pons  and  medulla   § Involved  rigidly,  programmed  automatic  behaviors  necessary  for  survival  as   well  as  providing  a  pathway  for  fiber  tracts  running  between  higher  and   lower  neural  centers   § Midbrain   o Cerebral  peduncles  (ascending/descending  fiber  tracts)   § Ascending  axons:  sensory   § Descending  axons:  motor   o Corpora  quadrigemina  (visual/auditory  reflexes)   § Tectal  plate   o Red  nucleus  (motor  coordination)   o Substantia  nigra  (movement,  mood,  reward,  addiction)   § Pons:     o Passage  of  sensory  and  motor  tracts   o Several  nuclei  associated  with  central  nervous  system   o Observe  autonomic  respiratory  centers   § Modifies  breathing  which  is  controlled  by  medulla   § Medulla:     o All  ascending  and  descending  tracts  between  spinal  cord  and  brain   pass  through  this  region   § Site  of  decussation   o Nuclei  important  for  motor  control   o House  vital  centers:  groupings  of  neurons  required  for  the  regulation   of  breathing  and  of  cardiovascular  responses   § Vasomotor  center:  controls  autonomic  innervation  of  blood   vessels   § Cardiac  control  center:  regulates  autonomic  nerve  control  of   the  heart;  closely  associated  with  the  vasomotor  control  center   § Respiratory  center:  sets  the  rate  and  depth  of  breathing  à   modified  by  the  pons   Cerebellum:   § Second  largest  structure  of  brain   § Receives  input  from  proprioceptors  and  works  together  with  basal  nuclei   and  cerebral  cortex  motor  area  in  coordination  of  movement     o Proprioceptor:  sensory  receptor  found  in  joints,  tendons  and  muscles   § Needed  for  motor  learning  and  coordinating  movement  of  different  joints  in   movement   § Required  for  proper  timing  and  force  required  for  limb  movements   o Ex.  Cerebellum  is  needed  to  touch  your  finger  to  your  nose,  bring  a   fork  of  food  to  your  mouth  or  find  keys  by  touch  in  your  pocket   § Purkinje  cells:  specific  cerebellar  neurons  that  the  functions  can  only  operate   through     § Current  research  suggest  may  have  other  functions  besides  motor   o Schizophrenia   § Individual  interprets  reality  abnormally   § Cognitive  dementia     • General  discoordination  of  sensoriomotor  and  mental   processes   o Autism     § Group  of  developmental  problems,  affect  child’s  ability  to   communicate  and  interact  with  others   § Smaller/abnormal  area  in  vermis   § Ataxia:  lack  of  muscle  coordination  during  voluntary  movements   o Indicative  of  cerebellum  damage   Reticular  Formation  and  Reticular  Activating  System   § An  interconnected  group  of  neurons  that  constitutes  an  arousal  system   o Reticular  activating  system  (RAS):  ascending  arousal  system   § Promotes  wakefulness  when  activated  and  sleep  when   inhibited   • Accomplished  via  use  of  excitatory  and  inhibitory   neurotransmittersà  work  in  tandem  like  a  switch   § Many  drugs  act  on  the  RAS,  promoting  sleep  or  wakefulness   § Narcolepsy:  neurological  disorder  where  a  person  will  fall   asleep  inappropriately  throughout  the  day  despite  having   ample  sleep   • Loss  of  LHA  neurons  that  release  polypeptide   neurotransmitters  that  promote  arousal   § Hypothesis  for  sleep-­‐wake  cycles:   o During  waking,  aminergic  neurons  dominate  and  during  REM  sleep   cholinergic  neurons  are  dominant   § Hypothalamic  neurons  project  to  RAS  and  influence  sleep-­‐ wave  cycles  in  regards  to  biological  clock  aligned  with   circadian  rhythms     Chapter  9:  The  Autonomic  Nervous  System     Autonomic  Nervous  System  Neurons   § Innervate  organs  whose  function  typically  not  under  voluntary  control   o Effectors  that  respond  to  autonomic  regulation  include  cardiac   muscle,  smooth  muscle  and  glands   § Unlike  somatic,  have  a  2-­‐neuron  pathway   o Central  nervous  system  à  preganglionic  neuron  à  autonomic   ganglion  à  postsynaptic  neuron  à  involuntary  effector   o Ganglion:  collection  of  neuron  cell  bodies   § Autonomic  control  is  an  integral  part  of  organ  systems  physiology   § Common  features:   o Resting  tone  (tension)  in  absence  of  nerve  stimulation   o Denervation  hypersensitivity   § Autonomic  nerve  damage  results  in  an  increase  of  target  tissue   sensitivity  to  stimulating  agents   • A  compensatory  event  to  nerve  damage   o Autonomic  innervation   § Target  tissues  display  autorythmicity   • Organs  “independent”  of  their  innervation   § Increase  or  decrease  target  tissue  activity  à  modulator  (not   simulator)   Divisions  of  the  ANS:   § Parasympathetic  (craniosacral)  nerves:  come  from  the  brainstem  and  sacral   region  of  the  spinal  cord   o “Break”   o “Rest  and  digest”   § Sympathetic  (thoracocolumbar)  nerves:  come  from  the  thoracic  and  lumbar   regions  of  the  spinal  cord   o “Gas”   o “Fight  or  flight”   § Note  ganglia  location:  for  sympathetic  most  ganglia  lie  close  to  the  spinal   cord  à  parasympathetic  ganglia  are  either  on  or  next  to  effector  organ   § Mass  activation:  stimulates  sympathetic  nerves  to  “rev  up”  organs  à  global   event   Adrenergic  Stimulation   § Response  of  target  tissue  dependent  on  receptor  displayed   o Alpha  or  beta-­‐adrenergic  receptors     § Subtypes  (do  not  have  to  know  subtypes)   o Act  via  G-­‐proteins   § Clinical  application   o Drugs  can  be  agonists  or  antagonists   § Use  of  drugs  that  specifically  stimulate/block  various  receptors   can  be  used  clinically  to  treat  disease   • Propanol     o Hypertension   o Non-­‐selective  beta  blocker   Cholinergic  stimulation:   § Preganglionic  release  is  always  excitatory,  postganglionic  release  can  be   either  excitatory  or  inhibitory     o Response  is  receptor  type-­‐dependent   § Other  autonomic  neurotransmitters  referred  to  as  nonadrenergic,   noncholingeric  fibers   Organs  with  dual  innervation   § Innervated  by  both  parasympathetic  nervous  system  and  sympathetic   nervous  system   § Action:     o Antagonistic:  most  common   o Complementary:  stimulation  of  either  division  causes  similar  effects   o Cooperative:  stimulation  causes  different  effects  by  parasympathic   and  sympathetic  nervous  system  that  work  together  to  promote  a   single  action   Organs  without  Dual  innervation   § Include:  adrenal  gland,  arrector  pili  muscle,  sweat  glands  and  most  blood   vessels   § Regulation  achieved  by  increase  or  decrease  in  ton  (firing  rate)  of   sympathetic  nervous  system  fibers   Control  of  Autonomic  nervous  system  by  higher  brain  centers   § Visceral  functions  regulated  by  autonomic  reflexes,  as  sensory  input  to  brain   centers  integrate  and  respond  by  modifying  preganglionic  neuron  activity   § Neural  centers  of  medulla  control  autonomic  nervous  system  activity   o Responsive  to  hypothalamus,  ie.  Higher  brain  center   § Major  regulatory  center  for  ANS   § Limbic  system   o Visceral  response  to  emotional  states   § Cerebellum         Chapter  10:  Sensory  Physiology   Sensory  system:  neural  mechanism,  which  processes  sensory  information  bringing   awareness  of  internal  and  external  environment     Sensory  Receptor  Characteristics:   § Muller’s  Law:   o Each  sensory  receptor  response  to  a  particular  modality  of   environmental  stimulus   o Brain  interprets  impulses  along  a  specific  neural  pathway  as  the   stimulus     § Transduces  stimulus  energy  into  electrochemical  energy   § Sensory  unit:     o Single  afferent  neuron  and  all  of  its  receptor  endings   o Receptive  field   § Overlap   o Modality  and  body  location   § Unique  pathway   § Specific  region  of  sensory  cortex   o Acuity,  or  precision   § Locate  and  discern  one  stimulus  from  another     § Amount  of  neuronal  input  convergence   § Each  sensory  nerve  ending,  however  stimulated,  gives  rise  to  its  own  specific   sensation   o Each  sensation  type  depends  not  on  the  nerve  it  travels  but  upon  the   part  of  the  brain  in  which  the  fibers  terminate   Factors  affecting  acuity:   § Sensory  unit  density  and  amount  of  overlap   § Size  of  receptive  field  covered  by  a  sensory  unit   § Greater  sensory  neuron  response  when  stimulus  applied  center  of  receptive   field   Lateral  Inhibition   § Occurs  in  the  central  nervous  system     § Most  important  mechanism  enabling  localization  of  stimulus  site   § Receptors  at  edge  of  stimulus  strongly  inhibited  compared  to  center   § Sensory  neuron  most  strongly  stimulated  inhibits  neighboring  sensory   neurons   Categories  of  sensory  receptors:   § Structural   o Simple  or  complex  in  design   o Peripheral  nerve  endings  free  (respond  to  pain  or  temperature)  or   encapsulated  (respond  to  pressure)     § Functional   o Characterized  by  type  of  stimulus  they  respond  to   § ChemoR:  chemical  stimuli  in  environment  or  blood   • Ex.  Taste  buds,  olfactory  epithelium  and  the  aortic  and   carotid  bodies   § PhotoR:  rods  and  cones  in  the  retina  of  the  eye   § ThermoR:  respond  to  temperature   § MechanoR:  stimulated  by  mechanical  deformation  of  the   receptor  cell  membrane     • Ex.  Touch  and  pressure  receptors  in  the  skin  and  hair   cells  within  the  inner  ear   § Nociceptor:  pain  receptors  that  depolarize  in  response  to   stimuli  that  accompany  tissue  damage   o Type  of  stimulus  information  delivered   § Proprioceptors:  muscles,  joints  and  tendons   • Provide  sense  of  body  position  and  allow  fine  control  of   skeletal  movements   § Cutaneous  receptors:   • Touch  and  pressure  receptors   • Heat  and  cold  receptors   • Pain  receptors   § Special  senses:     • Sight   • Hearing   • Equilibrium   • Taste   • smell   § Exteroceptor  vs.  Interoceptor     o Exteroceptors:  respond  to  external  stimuli   o Interoceptors:  respond  to  internal  stimuli   Sensory  Adaptation   § Tonic  receptor  –  slow  adapting   o Maintain  firing  frequency  during  application  of  stimulus   § Phasic  receptor  –  fast  adapting   o Respond  with  quick  burst  of  activity  when  stimulus  1  applied,  then   firing  rate  decreases   § Adaptation:  ability  to  cease  paying  attention  to  constant   stimuli   • Ex.  Shower  water  feels  much  hotter  when  you  first  step   in   o Quick  short  burst  of  impulses  when  stimulus  applied,  then  another   quick  short  burst  of  impulses  when  stimulus  removed   § “on-­‐off”  info   Receptor  (generator)  Potential   § In  response  to  stimulus,  sensory  endings  produce  local  graded  changes  in   membrane  potential   o Depolarizations  analogous  to  EPSPs   § In  sensory  nerve  endings,  these  potential  changes  in  response  to  stimulation   are  called  receptor  or  generator  potentials   o Since  sensory  neurons  are  Pseudounipolar,  the  action  potentials   produced  are  conducted  continuously  from  the  periphery  into  the   central  nervous  system   § Phasic  receptor:  ex.  Pacinian  corpuscle     o When  a  light  touch  is  applied  to  the  receptor  a  small  depolarization  is   produced   o Increasing  pressure  increases  the  magnitude  until  the  threshold   needed  for  an  action  potential  is  reached   o If  the  pressure  is  maintained  the  size  of  the  generator  potential   produced  quickly  diminishes   § Tonic  receptor:     o Generator  potential  it  produces  is  proportional  to  the  intensity  of  the   stimulus   o If  threshold  is  reached,  an  increase  in  the  generator  potential   amplitude  will  result  in  an  increase  in  action  potential  frequency     o Tonic  receptors  provide  information  about  the  relative  intensity  of  a   stimulus   Cutaneous  sensations   § Result  due  to  information  from  a  variety  of  sensory  receptors   § Somatic  sensations:  sensation  from  skin,  muscles,  bones  tendons  and  joints   § Somatesthetic  senses:  conscious  awareness  of  body    


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All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email


StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here:

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to

Satisfaction Guarantee: If you’re not satisfied with your subscription, you can contact us for further help. Contact must be made within 3 business days of your subscription purchase and your refund request will be subject for review.

Please Note: Refunds can never be provided more than 30 days after the initial purchase date regardless of your activity on the site.