Male repro system functions

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Male repro system functions

• Testes- produce sperm male sex hormone-
  testosterone
• Ducts transport, store, assist in maturation
  of sperm
• Accessory sex glands- secrete most of liquid
  portion of semen
• Penis- contains urethra
• passageway for ejaculation of semen
• excretion of urine

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Male repro anatomy
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Functions of each structure

• Scrotum- bag
• supporting structure for testes
• loose skin superficial fascia
• hangs from root of penis
• Testes- paired oval glands
• develop near kidneys descend into scrotum in
  latter half of 7th fetal month
• Sperm produced in seminiferous tubules
• Adjacent to seminiferous tubules are
• Leydig cells -secrete testosterone.

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Structure/Functions (2)

• Epididymis- lies along posterior border of each
  testis
• each consists of tightly coiled ductus epididymis
• where sperm motility ? over 10-14 day pd
• ductus stores helps propel sperm by peristaltic
  contraction of it smooth muscle
• Sperm may be stored for a month or more

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Structure/Functions (3)

• Ductus deferens or vas deferens- ?18 in
• stores sperm, can remain viable several months
• sperm not ejaculated are reabsorbed
• (as can happen in epididymis)
• Cut during vasectomy
• Ejaculatory ducts- ?1 in, formed by union of
  seminal vesicle ampulla of vas deferens
• eject sperm seminal vesicle secretions just
  before ejaculation - powerful propulsion of semen
  from urethra to exterior of body

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Structure/functions (4)

• Urethra- shared terminal duct of reproductive
  urinary system
• Passes thru
• prostate gland (prostatic urethra)
• urogenital diaphragm (membraneous urethra)
• penis (spongy urethra)
• Penis- passageway for ejaculation of semen
  excretion of urine

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Glands (1)

• Seminal vesicles- lies posterior to urinary
  bladder, anterior to rectum
• Function secrete an
• alkaline (neutralize acidic environment of male
  urethra), viscous fluid that contains fructose
  (ATP production), prostaglandins (contribute to
  sperm motility viability)
• may also stimulate
• muscular contraction in female reproductive tract
• clotting proteins
• About 60 of volume of semen

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Glands (2)

• Prostate gland- inferior to urinary bladder
  surrounds prostatic urethra
• Secretes milky fluid that contains
• 1. Citric acid- used in ATP production
• 2. Acid phosphatase- function unknown
• 3. Proteolytic enzymes- pepsinogen, lysozyme,
  amylase, and hyaluronidase
• About 25 volume of semen

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Glands (3)

• Bulbourethral (Cowpers) glands- inferior to
  prostate on either side of membraneous urethra
• During sexual arousal secrete an alkaline
  substance that protects passing sperm by
  neutralizing acids from urine in urethra
• Also secrete mucus- lubricating end of penis
  lining urethra to ? of sperm damaged during
  ejaculation

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Descent of Testes

• In both sexes, gonads originate in lumbar region
  descend caudally during fetal development
• In male fetus, testes descend toward scrotum,
  followed by their blood vessels nerves
• testes require a cool location for sperm
  formation
• testes reach pelvis near inguinal region in month
  3
• testes proceed no further until month 7, when
  they suddenly quickly pass thru the inguinal
  canal enter the scrotum

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Parts of spermatozoan

• Head- contains nuclear material acrosome
• Acrosome- dense lysosome-like body in head of
  sperm cell
• contains enzymes that facilitate penetration of
  sperm cell into secondary oocyte
• Midpiece- contain numerous mitochondria
• provides ATP for locomotion
• Tail- typical flagellum
• propels sperm

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Gametes are haploid

• Haploid- (n) having half the of chromosomes
  characteristically found in somatic cells of an
  organism
• Sperm
• Oocyte
• Diploid- (2n) having the of chromosomes
  characteristically found in the somatic cells of
  an organism

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Meiosis vs. Mitosis

• Meiosis- cell division during production of
  gametes
• 2 successive nuclear divisions resulting in
  daughter cells with haploid number chromosomes
• 2n ? n
• Mitosis- division of nucleus that ensures each
  new daughter nucleus has same number kind of
  chromosomes as original parent nucleus
• Process includes the 2 full sets of chromosomes
  sent into 2 separate equal nuclei
• Daughter cells have diploid number of chromosomes
• 2n ? 2n

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Maturation of sperm
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• Hormonal control of spermatogenesis

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Hormone producing cells

• Sertoli cells- supporting cell of seminiferous
  tubules
• secretes fluid for supplying nutrients to sperm
• Secrete hormone inhibin
• phagocytizes excess cytoplasm for spermatogenic
  cells
• mediates effects of FSH testosterone
• Secrete Mullerianinhibiting substance during
  fetal development
• Leydig cells- secretes testosterone
• located in CT between seminiferous tubules

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• Negative feedback loop for testosterone

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Female repro structures

• Ovaries produce 2 oocytes and hormones
• Estrogens, progesterone, inhibin, relaxin
• Uterine tubes transport 2 oocyte to uterus.
  Also, site of fertilization
• Uterus- implantation, fetal development, labor
• Vagina receives penis during intercourse,
  passageway for childbirth
• Mammary glands- synthesize, secrete, eject milk
  for nourishment of newborn

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Oogenesis

• During fetal development, primordial germ cells
  migrate yolk sac? ovaries
• Germs cells in ovary oogonia
• Are diploid
• Most degenerate atresia
• Few develop into primary oocytes which enter
  prophase I of meiosis during fetal development do
  not complete until puberty
• 1 oocyte surrounded by follicular cells
  primordial follicle

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Primary oocyte development

• 200,000 2,000,000 oocytes/ovary at birth
• 40,000 still present at puberty
• ? 400 will mature and ovulate
• Monthly FSH LH stimulate development of
  several primordial follicles, typically only one
  matures enough to be ovulated
• Primary follicle ? secondary follicle ? Graafian
  follicle? follicle ruptures ovulation
• See figure 28.13

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Oogenesis

• One female gamete (haploid) forms from one
  oogonium (diploid)
• How many male gametes are formed from one diploid
  spermatogonium?
• Table 28.1 summarizes

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Hormonal Control of Ovulation
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Female hormone functions
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Human sexual response

• 4 stages
• Excitement arousal, ParasympNS causes
  vasocongestion
• HR bp?, skeletal muscle tone, hypervent
• Plateau excitement sustained intensely, sex
  flushredness of face chest
• Orgasm- briefest, ejaculation, muscular
  contractions in both sexes. SympNS causes smooth
  muscle contraction of genitals
• Resolution- relaxation return to unaroused
  state