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PSYC370 Ch 13.pdf

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Department
Psychology
Course
PSYC 370
Professor
Janet L Menard
Semester
Winter

Description
PSYC  370   Chapter  13   Hormones  and  Sex     Men  are  men,  and  women  are  women  assumption.     MAMAWAWA:  “men-­‐are-­‐men  and  women-­‐are-­‐women  assumption.”     Limitations  of  the  MAMAWAWA   -­‐ Gender  is  not  discrete,  mutually  exclusive,  or  opposites   -­‐ Inconsistent  with  evidence     Developmental  and  activational  effects  of  sex  hormones.     How  hormones  influence  sex:   1. Developmental  effects  (organizational  effects)   -­‐ Influence  development  from  the  time  of  conception  to  sexual  maturity.  “Development”   refers  to  the  development  of  the  anatomical,  physiological,  and  behavioural  characteristics   of  gender.     2. Activational  effects   -­‐ Activation  of  behaviours  related  to  reproduction.       Neuroendocrine  system     Endocrine  glands:  organs  that  secrete  hormones.  Figure  below  lists  the  endocrine  glands.     Glands.     -­‐ Exocrine  glands   -­‐ Endocrine  glands     Exocrine  glands:  interact   with  the  outside  world;   release  chemicals  into   ducts,  which  carry  them   (usually)  to  the  surface  of   the  body.       Endocrine  glands:   release  chemicals   (hormones)  directly  into   the  circulatory  system.     Hormones  act  directly  on   targets.   (13  :  1)   PSYC  370   Gonads.     Gonads:  male  testes  and  female  ovaries.         Testes:  produce  sperm.       Ovaries:  produce  ova.     Sex  chromosomes:  contain  genetic  programs  that  guide  sexual  development.     -­‐ Production  and  release  of  sex  steroid  hormones  (androgens,  estrogens,  &  progestins)  at   the  gonads  (more  to  follow,  see  sex  steroids  section).     Classes  of  hormones.     How  hormones  interact  with  their  targets:   -­‐ Bind  at  receptors  in  the  cell  membrane     Classes  of  hormones  fall  into  three  categories.     1. Amino  acid  derivative  hormones:  synthesized  from  an  amino  acid  molecule.   -­‐ e.g.,  Epinephrine,  which  is  synthesized  from  the  amino  acid  tyrosine.       2. Peptide  hormones  and  protein  hormones:  chains  of  amino  acids,  either  short  (peptide)   or  long  (protein).     3. Steroid  hormones:  synthesized  from  cholesterol  (fat  molecule).   -­‐ Small,  fat-­‐soluble,  can  enter  cell  membranes     -­‐ Bind  with  receptors  at  the  cell  membrane,     -­‐ &  can  also  enter  the  cell,  bind  with  receptors  intracellularly,  and  alter  gene  expression.     -­‐ All  of  the  hormones  that  influence  adult  sexual  behaviour  (i.e.,  sex  hormones)  are  steroid   hormones.     Sex  steroids.     -­‐ Gonads  produce  and  release  steroid  hormones     Main  classes  of  gonadal  hormones:   1. Androgens:  e.g.,  testosterone.     2. Estrogens:  e.g.,  estradiol.   3. Progestins:  e.g.,  progesterone.       All  are  excreted  in  both  genders.  Males  excrete  slightly  more  androgens,  females  slightly  more   estrogens.   (13  :  2)   PSYC  370   Progesterone:  prepares  uterus  and  breasts  for  pregnancy;  function  in  men  is  unclear.     The  adrenal  cortex  is  another  location  that  secretes  sex  hormones.       Hormones  of  the  pituitary.     Tropic  hormones:  primary  function  is  to  influence  the  release  of   hormones  from  other  glands.     Gonadotropin:  tropin  hormone  that  signals  the  gonads  to  release  its   hormones.       Pituitary  is  referred  to  as  the  “master  gland,”  because  most  of  its   hormones  are  tropic  hormones.     -­‐ Posterior  pituitary   -­‐ Anterior  pituitary     Anterior  pituitary  is  the  structure  that  actually  releases  the  hormones.   If  you  want  to  be  technical,  it  is  the  master  gland.       Posterior  started  off  as  part  of  the  hypothalamus  and  the  anterior  stated  off  as  part  of  the  roof  of   the  mouth.         Female  gonadal  hormone  levels  are  cyclic;  male  gonadal  hormone  levels  are  steady.     Menstrual  cycle  is  a  manifestation  of  the  fluctuations  of  gonadal  hormones,  which  follows  a  28-­‐ day  cycle.       Men  do  not  have  much  change  in  gonadal  hormone  levels  from  day-­‐to-­‐day.       Neural  control  of  the  pituitary.     Hypothalamus  controls  the  anterior  pituitary   -­‐ Notice  connection  in  above  diagram     -­‐ Mechanism  of  action  is  unknown     Anterior  pituitary  receives  no  neural  input  from  the  hypothalamus  –  so  what  is  the  mechanism  of   action?     Control  of  the  anterior  and  posterior  pituitary  by  the  hypothalamus.     Control  of  the  posterior  pituitary  is  different  from  the  control  of  the  anterior  pituitary.       (13  :  3)   PSYC  370   1. Posterior  pituitary     -­‐ Vasopressin:  reabsorption  of  water  by  the  kidneys;  also  called  the  antidiuretic  hormone.   -­‐ Oxytocin:  uterine  contractions  during  labour  +  secretion  of  milk  during  suckling.     - Peptide  hormones   - Synthesized  in  the  paraventricular  nuclei  and  the  supraoptic  nuclei     Vasopressin  and  oxytocin  are  synthesized  in  the  paraventricular  nuclei  and  the  supraoptic  nuclei.   They  are  transported  to  the  posterior  pituitary,  where  they  are  stored  until  an  action  potential   triggers  their  release.       Neurosecretory  cells:  neurons  that  release  hormones  into  general  circulation.   -­‐ Paraventricular  nuclei     -­‐ Supraoptic  nuclei         2. Anterior  pituitary     Hypothalamopituiatry  portal  system:  vascular  network  that  carries  hormones  from  the   hypothalamus  to  the  anterior  pituitary.       Portal  vein:  vein  that  connects  one  capillary  network  to  another.     (13  :  4)   PSYC  370   A  network  of  capillaries  from  the  hypothalamus  feeds  into  a  bundle  of  portal  veins  that  carry   blood  down  into  the  anterior  pituitary.       The  figure  has  a  decent  explanation  of  the  hypothalamic  control  of  both  sides  of  the  pituitary.     Discovery  of  hypothalamic  releasing  hormones.     Releasing  hormones:  stimulate  the  release  of  anterior  pituitary  hormones.     Release-­‐inhibiting  factors:  inhibit  the  release  of  anterior  pituitary  hormones.       Thyrotropin-­‐releasing  hormone:  signal  from  the  hypothalamus  for  the  anterior  pituitary  to   release  thyrotropin,  which  signals  the  release  of  hormones  from  the  thyroid  gland.     Thyrotropin:  triggers  release  of  hormones  from  the  thyroid  gland.     Discovery  of  thryotropin-­‐releasing  hormone  confirmed  that  hypothalamic  releasing  hormones   control  the  release  of  hormones  from  the  anterior  pituitary.     Gonadotropin-­‐releasing  hormone:  stimulates  release  of  gonadotropins  from  the  anterior   pituitary.     -­‐ Follicle-­‐stimulating  hormone   -­‐ Luteinizing  hormone     All  hypothalamic  releasing  hormones  are  peptide  hormones.       Summary  of  this  section:  the  hypothalamus  controls  the  anterior  pituitary  via  its  hypothalamic   releasing  hormones.     Regulation  of  hormone  levels.     Three  signals  regulate  hormone  release.     1. Neural  signals     -­‐ All  endocrine  glands  (except  anterior  pituitary)  regulated  by  signals  from  the  nervous   system     -­‐ Cerebral  neurons  control  endocrine  glands  that  are  located  inside  the  brain  (e.g.,  pituitary   and  pineal  glands).     -­‐ Autonomic  nervous  system  (sympathetic  and  parasympathetic)  controls  endocrine   glands  outside  the  brain.     -­‐ Experience  plays  a  role  (e.g.,  some  animals  mate  only  in  spring  –  experience  impacts   release  of  sex  hormones).   (13  :  5)   PSYC  370   2. Hormonal  signals     -­‐ e.g.,  Tropic  hormones  stimulate  the  release  of  hormones  from  other  structures     -­‐ Feedback  systems     3. Nonhormonal  chemicals     -­‐ Glucose  (e.g.,  triggers  release  of  insulin)   -­‐ Calcium   -­‐ Sodium     Pulsatile  hormone  release:  hormones  typically  released  in  pulses  throughout  the  day;  large   surges  lasting  a  few  minutes.       -­‐ Regulation  of  hormone  levels  based  on  frequency  and  duration  of  pulses     Summary  model  of  gonadal  endocrine  regulation.                                                  
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