Reproductive Systems – Slideshow |, Study notes of Physiology

Download Reproductive Systems – Slideshow | and more Study notes Physiology in PDF only on Docsity! ce) Fa Cn =e ine ee OW ce) ~~ Functions  of  the   Reproductive  Systems Produce  gametes  (eggs  &  sperm)  in  the  gonads   (ovaries  &  testes) Produce  sex  hormones   Ovaries  produce  estrogens  (mainly  estradiol) Testes  produce  androgens  (mainly  testosterone) Facilitate  sexual  intercourse Produce  offspring Cremaster  muscle   adjusts  the  position  of   the  testes   Optimal  temp  for   spermatogenesis  is  2-­‐3   degree  Celsius  below   core  body  temp Penis Conveys  urine  and  semen   through  the  urethra  to   the  outside Consists  of  3  columns  of   erectile  tissue   Contain  blood  sinuses  and   the  urethra 2  corpora  cavernosa 1  corpus  spongiosum Surrounds  urethra Glans  (head  of  penis) Enlargement  of  the  distal  end  of   the  corpus  spongiosum Distal  urethra  forms  the  external   urethral  orifice Covered  by  prepuce  (foreskin) Removed  in  circumcision Spermatogenesis Spermatogonia  produce   primary  spermatocytes Undergo  meiosis  to  produce   spermatids Sperm  cells  have  23   chromosomes As  they  mature,  they  acquire   a  tail  and  become  functional   sperm Sperm  Anatomy The  sperm  head  contains   the  nucleus   DNA  consists  of  haploid  (half)   number  of  chromosomes The  acrosome contains   enzymes  which  help  the   sperm  enter  the  ovum Mitochondria  supply  ATP   for  locomotion The  flagellum (tail)  whips   back  and  forth,  propelling   the  sperm. Vas  Deferens Transports  sperm   From  the    epididymis   to  the  urethra  during   ejaculation 18  inches  long   Loops  over  ureter  and   down  posterior  side  of   urinary  bladder At  ejaculation, peristalsis  of   smooth  muscle  of  ducts  in  the   epididymis  propels  sperm  into   the  vas  deferens Sperm  not  ejaculated   degenerate  and  are  reabsorbed Viable  sperm  can  also  linger   here  for  several  weeks! Accessory  Glands Secrete  most  of  fluid  in  semen Only  5%  of  semen  consists  of  sperm Accessory  glands  include: Seminal  vesicles Prostate  gland Urinary bladder Superior pubic ramus (cut) Ductus (vas) deferens Urethra Corpus cavernosum Corpus spongiosum Penis Glans penis Prepuce Large intestine Seminal vesicle Ejaculatory duct Prostate gland Bulbourethral gland Anus Epididymis Testis Scrotum Accessory  Glands Prostate  Gland Located  inferior  to  the  urinary  bladder;  proximal  end   of  the  ureter Secretes  25%  of  fluid,  including:   Alkaline  substances  to  neutralize  the  hostile  acidic   environment  of  the  male  urethra  and  female  vagina! Other  substances  to  enhance  sperm  motility. Urinary bladder Superior pubic ramus (cut) Ductus (vas) deferens Urethra Corpus cavernosum Corpus spongiosum Penis Glans penis Prepuce Large intestine Seminal vesicle Ejaculatory duct Prostate gland Bulbourethral gland Anus Epididymis Testis Scrotum Arousal  &  Ejaculation During  arousal  arteries  to  the  penis  dilate Fill  sinuses  in  corpora  cavernosa  &  corpus  spongiosum  with   blood  (erection) Prior  to  ejaculation,  accessory  glands  release  their  fluids  into   ejaculatory  duct Ejaculation  involves  a  sympathetic  reflex Sphincter  at  base  of  bladder  closes Contractions  of  vas  deferens  propel  sperm  into  urethra  and   out  via  external  urethral  orifice Path  of  Sperm #1  Seminiferous  tubules                               #2  epididymis                                                           #3  vas  deferens                                                       #4  urethra                                                                           #5  external  urethral    orifice Average  volume  of  semen  =   2.5  -­‐ 5  ml 50  -­‐ 150  million  sperm/ml Less  than  20  million/ml  is   considered  infertile             Let me out! Let me out! Hormonal  Control:     Male The  hypothalamus  releases  gonadotropin  releasing   hormone  (GnRH)  that  targets  the  anterior  pituitary Anterior  pituitary  then  releases  its  own  hormones  in   response Target  the  male  (and  female)  gonads Endocrine  review  time  .  .  .   Negative  feedback  among  the  hypothalamus,  the  anterior  pituitary,   and  the  testes  controls  the  concentration  of  testosterone  (and therefore  sperm  production)  in  the  male Female  Reproductive  Anatomy Internal  anatomy: Ovaries Uterine  tubes/Fallopian  tubes   Uterus   Vagina External  anatomy: Vulva  (pudendum) Mons  pubis Labia  and  vestibule Clitoris Ovaries Produce  ova  (eggs)  via  oogenesis Produce  female  sex  hormones 2 Oogonium &® Meiosis | Primary oocyte First polar body y\ @ Secondary oocyte Ovulation Nn Sperm + Secondary cell oocyte Fertilization ib \ @ Second ‘ polar body e) Ovum During fetal development meiosis | begins. After puberty, primary oocytes complete meiosis |, which produces a secondary oocyte and a first polar body that may or may not divide again. The secondary oocyte begins meiosis II. A secondary oocyte (and first polar body) is ovulated. Meiosis II After fertilization, meiosis II resumes. The oocyte splits into an ovum and a second polar body. The nuclei of the sperm cell and the ovum unite, forming a diploid (2n) zygote. e Events of oogenesis Uterine  Tubes                             (Fallopian  Tubes/Oviducts) Transport  sperm  to  ovum,  and  fertilized  egg  to  uterus Infundibulum :    funnel-­‐shaped  end  of  tube,  open  to  pelvic   cavity Fimbria   into  tube  at  ovulation Inside  of  tube  is  lined  with  cilia  that  propel  egg  toward   uterus Also  assisted  by  peristalsis  of  muscular  wall  of  uterine  tube. Uterine tube ] Ovary Body of uterus Secondary Endometrium -—- Myometrium Perimetrium Cervix Cervical orifice Vagina Vagina Muscular  tube   extending  from  cervix   to  exterior  of  body Birth  canal  and  outlet   for  menstrual  flow The  vagina  is  situated  between  the  bladder  and  the   rectum Vulva Includes:   Mons  pubis Elevation  of  adipose   tissue  to  cushion  pubic   symphysis Labia  majora  (outer   lips),  and  labia  minora   (inner  lips)  are  skin  folds (singular:    labium  majus  and  labium  minus) Enclose  inner  genital  structures     e Bartholin’s glands (greater vestibular glands) provide lubrication upon sexual arousal Female  Reproductive  Cycle The  female  reproductive  cycle  consists  of  the  events   that  occur  simultaneously  in  both  the  ovaries  and  the   uterus: Ovarian  cycle involves  the  maturation  of  the  ovum,  or  egg  cell Uterine  cycle (menstrual  cycle)  involves  the  changes  in  the   endometrium  of  the  uterus TABLE 27.5 HORMONES OF THE OVARIAN AND MENSTRUAL CYCLES Secreted by Major Roles Releasing hormone FSH LH Estrogen Estrogen and progesterone Hypothalamus Pituitary Pituitary Ovarian follicle Corpus luteum Regulates secretion of LH and FSH by pituitary Stimulates growth of ovar- ian follicle Stimulates growth of ovar- ian follicle and production of secondary oocyte; pro- motes ovulation; promotes development of corpus luteum and secretion of hormones Low levels inhibit pituitary; high levels stimulate hypo- thalamus; promotes endometrium Maintain endometrium; high levels inhibit hypo- thalamus and pituitary; sharp drops promote menstruation In  the  ovary,  FSH  stimulates  the  ripening  of  a  follicle,  a   pocket  that  holds  an  egg  cell  (ovum) The  maturing  follicle  secretes  increasing  amounts  of   estrogen  into  the  bloodstream Thickens  the  endometrium  of  the  uterus   preparation  for  the   implantation  of  a  fertilized  egg Anterior  view                                                            Lateral  view A  sudden  surge  of  LH  causes  ovulation Follicle  ruptures  and  releases  the  egg  into  the  oviduct   (Fallopian  tube)   In  the  brain,  the  hypothalamus  and  anterior  pituitary  release   their  hormones  into  the  bloodstream The  blood  carries  FSH  and  LH  to  the  ovary In  the  ovary,  FSH  ripens  the  follicle   As  the  follicle  matures,  it  secretes  more  and  more  estrogen,   which  thickens  the  endometrium  and  prepares  it  for  the  arrival  of   a  fertilized  egg Rising  levels  of  estrogen  cause  a  sudden  increase  in  LH     The  LH  surge  causes  ovulation.    The  ruptured  follicle  becomes  the   corpus  luteum If  a  fertilized  egg  does  not   reach  the  lining  of  the  uterus,   the  corpus  luteum   degenerates Without  a  functional  corpus   luteum,  progesterone  and   estrogen  levels  decline. Low  estrogen  and   progesterone  can  no  longer   maintain  the  endometrium,   and  it  starts  to  break  down       As  estrogen  and   progesterone  decline,   FHS  and  LH  levels   begin  to  rise  again     The  lining  of  the   uterus  sloughs  off  as   menstrual  discharge Under  the  influence  of   FSH,  another  follicle   begins  to  ripen  in  the   ovary,  and  the  cycle   begins  anew Maintaining  the  Corpus  Luteum   (and  the  Pregnancy) Progesterone  needs  to  stay  high  in  order  for  the   endometrium  to  support  a  developing  embryo   Critical  that  the  corpus  luteum  stays  functional secretes  its  own  hormone  that  maintains  the  corpus   luteum human chorionic  gonadotropin,  or  HCG