Chapter 27 Reproductive Physiology
Reproductive System
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Homeostasis of the Species
strategies of life
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need more individuals
need way for species to survive vs. environment:
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make a lot of individuals ; identical
make a few individuals
; variety
purpose of sex :
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to join sex organs ?
to join gametes ?
to join DNA ?
sexy words
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genitalia
sex organs
DNA
genetic code
sex cells
gametes
• ovum
• sperm
primary sex organs
= gonads
produce sex cells
produce hormones
• ovaries
• testes
accessory sex organs
aid sex cells, organs
genetics
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gene
code for 1 protein
DNA
many genes
chromosome
1 strand of DNA
humans have 23 different chromosomes
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haploid # =
23
humans have pairs of each chromosome
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diploid # =
46
(23 pairs)
homologous chromosome pair 23 pairs
maternal + paternal
sister chromatids
during mitosis and meiosis
duplicates of each chromosome
mitosis
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1 diploid cell  2 identical diploid cells
this is how tissues / organisms grow
stages:
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( DNA synthesis)
prophase
metaphase (metaphase plate)
anaphase
telophase
cytokinesis
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sister chromatids
problem
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How can we get variety ?
How can we keep diploid # ?
Meiosis
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mitosis
1 diploid cell  2 identical diploid cell
meiosis
1 diploid cell  4 different haploid cells
• provides genetic variety
haploid cells =
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gametes
male
sperm
spermatogenesis
female
ovum
oogenesis
zygote
united ovum and sperm
(diploid)
2 cell divisions w/ only 1 DNA replication
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meiosis I
meiosis II
Meiosis I
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Meiosis I
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prophase
– tetrads
– crossover
4 chromatids
homologous
swap DNA between maternal and paternal chromosomes
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metaphase
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anaphase , telophase, cytokinesis
– tetrads line up across metaphase plate
result:
2 different haploid cells
w/ 23 chromatid pairs
Meiosis II
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Meiosis II
like mitosis , but no DNA replication
result :
4 gametes
23 chromosomes
spermatogenesis
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spermatogonia
stem cells
primary spermatocyte
start meiosis I
secondary spermatocyte
start meiosis II
spermatids
after meiosis II
spermatozoa
developed flagella
where ?
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spermatogenesis
testes
sperm maturation
epididymis
sperm
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head
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nucleus
DNA
acrosome
hydrolytic enzymes
midpiece
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mitochondria
nutrients
flagellum
glucose, ATP, water
(46)
male structures
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testes
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seminiferous tubules
produce sperm
interstitial cells
testosterone
epididymis
store sperm
ductus deferens = vas deferens
passageway for sperm
seminal vesicle
produce semen
prostate gland
other secretions
penis
urethra
erectile tissue
oogenesis
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oogonia
stem cells
primary oocytes
• meiosis I
• resume meiosis I
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secondary oocyte
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ovum
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pauses at birth
puberty
1st polar body
• meiosis II
• ovulation
• completes meiosis II only if fertilized
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• gamete
3 polar bodies
haploid
developing ovum
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primordial follicle
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primary follicle
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oocyte + follicle cells
resume meiosis
primary oocyte
granulosa cells
secondary follicle
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secondary oocyte
Graafian follicle
ovum
gamete
female structures
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ovary
fallopian tubes
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oviducts
path of ovum to uterus
site of fertilization
uterus
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body
cervix
vagina
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birth canal
uterine wall
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perimetrium
outer serous layer
myometrium
smooth muscle
endometrium
mucosa lining
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stratum basalis
– always present
basal layer
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stratum functionalis
functional layer
– formed each cycle
– lost during menses
– site of implantation
– future placenta
hormone abbreviations
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GnRH
gonadotropic releasing hormone
FSH
follicle stimulating hormone
LH
luteinizing hormone
(ICSH)
interstitial cell stimulating hormone
hormones - general
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GnRH
FSH
LH
follicle growth
meiosis
hormone secretion
maintain gonads
ovum
progesterone, estrogen
sperm
testosterone
hormonal feedback
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gonadal steroids
inhibit GnRH , FSH , LH
gamete production
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inhibin
inhibits FSH (GnRH ?)
hormones - male
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FSH
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ICSH
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testosterone
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inhibin
ant. pituitary
• stim spermatogenesis
• via androgen binding protein (ABP)
ant. pituitary
• stim testosterone
interstitial cells
• spermatogenesis
• sperm maturation
sustentacular cells
• inhibit FSH and LH (inhibits GnRH)
• when sperm count is high
uterine cycle
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menstrual phase
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proliferative phase
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day 1 – 5
loss of functional layer
new functional layer
stim by estrogen
until ovulation
day 5 – 14
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day 15 – 28
secretory phase
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growth of functional layer
secrete mucous , glucose
stim by progesterone
ovarian cycle
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follicular phase
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primary follicle resumes meiosis
stim by FSH
follicle produces estrogen
ovulation
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oocyte released from Graafian follicle
LH = luteinizing hormone
luteal phase
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corpus luteum
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corpus albicans
• produces progesterone
• functions ~ 3 months , if pregnant
degenerated corpus luteum
if no pregnancy
hormonal events
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low estrogen
stim GnRH
FSH
stim oogenesis
follicle produce estrogen
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estrogen
stim uterus
stim LH
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LH
ovulation
corpus luteum
progesterone
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progesterone
grow uterus
inhibit GnRH , LH
FSH , LH
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w/o fertilization
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corpus luteum makes progesterone
progesterone
 LH
w/o LH
corpus luteum degenerates
stops making progesterone
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 progesterone
functional layer dies
menstruation
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 progesterone and estrogen   GnRH , FSH , LH
new cycle starts
w/ fertilization
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hCG =
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human chorionic gonadotropin
made by embryo
(chorion)
~ 14d after ovulation
absorbed into mother’s blood
stim corpus luteum
• continue to produce progesterone
• progesterone maintains uterus
growth of placenta
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= pregnancy test
produced until placenta takes over ~ 3-4 month
mammary glands
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modified sweat glands
alveolar glands
produce milk
lactiferous ducts
gland to nipple
prolactin
• stim alveolar glands
oxytocin
• stim milk release
puberty
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gonads become active
GnRH inhibited since birth
decrease inhibition
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increases GnRH levels
glutamate stim GnRH
increased FSH and LH
stim meiosis
estrogen and testosterone
secondary sex characteristics
menarche
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1st mentrual period
 GnRH
gradual  FSH and LH
few years until ovulation
menopause
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gradual  ovary sensitivity to FSH and LH
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gradual  estrogen levels
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no oogenesis
ovulation ceases ~ age 46 – 54
 estrogen
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estrone
weak estrogen still made in adipose
vasodilation “hot flashes”
uterus, vaginal wall atrophy
osteoporosis
HRT hormone replacement therapy
• prevent osteoporosis?
• risk of breast cancer?
birth control
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Birth control meds
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prevent ovulation
estrogen + progesterone
Norplant
skin implant
(5 years)
Depo-Provera
injection (3 months)
Ortho-Evra
skin patch
morning after pill
prevent implantation or
fertilization
RU-486
uterine contraction
prevent implantation
cause miscarriage
inhibin ?
more birth control
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tubal ligation
vasectomy
rhythm