reproductive system Flashcards
reproductive system
function: varies over lifetime
adult:reproduction - product gametes (spermatoza/oocytes),23 chromosomes
- produce sex steroids (eg. androgens, progesterone, estrogen)
- females: pregnancy and delivery
mitosis vs meiosis
genetic diversity through sexual reproduction, compared to asexual reproduction
mitosis - double-structured chromosomes are split apart and cells split with them
meiosis - pairing of chromosomes, pulled apart, cells contain 23 double-structured chromosomes, then are split again to 4 cells with 23 single-structure chromosomes
developmental origin of the male reproductive track
male fetus at 7-9 weeks
at 6 weeks: SRY (sex determining region Y turns on)
stimulates the indifferent gonads to be testes
testes now produces Mullerian Inhibiting Hormone (MIH) and testosterone
MIH causes the reduction of the female reproductive structures
testosterone causes the maturation of the male reproductive structures
male anatomy
testes in external environment, are kept a little cooler to perform optimally
epididymis - sperm maturation, must reside to mature
ductus deferens - sperm travels
seminal gland - adds fluid to the sperm
the testis
vas deferens: important for sperm & fluid release
epididymus: sperm storage & maturation
seminiferous tubules: sperm, fluid production
seminiferous tubules
spermatocytes
- adult stem cells
- developing sperm cells
sertoli cells
- support & regulate spermatogenesis
- blood testes barrier
- produce inhibin
leydig cells
- produce testosterone
- located in the space between seminiferous tubules
spermatogenesis
spermatozoa
spermatids
2º spermatocytes
1º spermatocytes
spermatogonia
spermiogenesis
mature sperm
head - nucleus, acrosome
tail - neck, middle piece, principal piece, end piece
abnormal gametes
abnormal spermatozoa are seen frequently
up to 10%
head or tail
giants or dwarfs
unlikely to fertilize due to motility issues
reproductive organs
seminal vesicles
- bulk of fluid
- fructose rich nourishes the sperm
prostate
- alkaline fluid to neutralize acidic environment of the vagina
bulbourethral glands
- alkaline fluid to neutralize the acidic environment of the ureter
hormonal release of testosterone
leydig cells → testosterone
testosterone → LH (luteinizing hormone) and FSH (follicle stimulating hormone)
testosterone → gonadotropin releasing hormone → gonadotropins
testosterone
steroid, hydrophobic, intracellular testosterone receptors, bound to proteins in blood
testosterone + aromatase → estradiol
testosterone effects
negative feedback
spermatogenesis
secondary sex characteristics
anabolic reactions (e.g. muscle mass)
testosterone levels throughout life
sex of baby can be determined - around 5 months
high levels right after birth - protection against infection and disease
andropause
- fatigue
- reduced fertility but not lost
- reduced muscle mass
benign prostatic hyperplasica (BPH)
benign prostatic hyperplasia (BPH)
normal prostate - urethra is not compressed
enlarged prostate - urethra is compressed and is difficult to urinate
prostate cancer
most diagnose cancer among men
1/7 canadian men will be diagnosed with prostate cancer in their lifetime
spermiogenesis
spermatogonia → 1º spermatocytes → 2º spermatocytes → spermatids
→ spermatozoa
effects of anabolic steroid
(luteinizing hormone) LH and (follicle stimulating hormone) FSH
leydig cells create testosterone
testosterone affects the hypothalamus
hypothalamus affects the anterior pituitary gland (which creates gonadotropins)
effects of testosterone:
- increased muscle mass
- increased red blood cell count (viscous blood)
- secondary sex characteristics
- negative feedback onto hypothalamus and anterior pituitary
- spermatogenesis
female reproduction organs
fimbriae
fallopian tube - passage for sperm and oocyte
ovary - oogenesis + hormones
uterus - site for implantation
cervis - entrance to uterus
vigina - site of sperm deposition, removal of menstrual fluid
ovaries: hormone & gamete production
- paired
- located in pelvis
- gametes: oocytes
- produced by oogenesis
- all oogonia develop prior to birth
oogenesis
fetal period
- oogonia - diploid stem cells of ovaries
- begin meiosis I, stops at prophase
child
- remains inactive in cortex of immature ovary until puberty
puberty
- small number activated each month recruited by FSH
- only one continues through meiosis
fertilized zygote
atresia of oocytes
amount of oocytes with age
folliculogenesis of the maturing oocyte
male - the cells that help sperm develop are part of the testes. They include the Sertoli and Leydig cells
female - the cells that help the oocyte develop make up the follicle that surrounds the oocyte. They are called Theca and Granulosa cells
primordial follicle
- primary oocyte
- granulosa cells
primary follicle
- 1º oocyte
- zona pellucida
- granulosa cells
secondary follicle
- 1º oocyte
- zona pellucida
- granulosa cells
- theca cells
Graafian follicle
- 1º oocytes → 2º
- zona pellucida
- granulosa cells
- theca cells
follicle development
primordial follicle
secondary follicle
graafian follicle
primary follicle
support cells: theca cells and granulosa cells
viability of gametes
oocytes
- usually fertilized within 12 hours of ovulation
- cannot be fertilized after 24 hours
spermatozoa
- viable for approximately 48 hours in female reproductive tract
oocyte and follicle stages
abnormal gametes
ovarian follicle may contain 2-3 distinguishable oocytes
may contain multiple nuclei
these are infrequent and often degenerate before reaching maturity
insufficient egg quality: poor maturation and cytoplasm health
human 3-day embryos from ART of one patients
A: recipient egg fertiziled with husband’s sperm
B: recipient egg injected with donor’s sperm
C: recipient egg injected with donor ooplasm fertilized with husband’s sperm
babies are born with three genomes: the nuclear component of the mother & father and the mtDNA form both the recipient and the donor
assisted reproductive technologies
- IUI-intra uterine insemination
- oocyte retrieval
- IVF/ICSI
- embryp transfer
- surrogate mother
- oocyte cryopreservation and cancer
- embryo cryopreservation
hormonal regulation
early to mid-follicular phase
cell types and functions
oocyte: “egg”
theca & granulosa cells: produce sex steroids
regulating reproductive function
GnRH → gonadotropins
gonadotropins → FSH and LH
FSH and LH → Theca cells + Granulosa cells
Theca cells → androstenedione (estrogen pre-cursor and stimulates granulosa cells)
granulosa cells create estrogen
at certain levels estrogen is an inhibitory hormone
once hits a certain level is a positive feedback loop hormone
early to mid-follicular phase
FSH + LH is inhibited by estrogen
estrogen causes the granulosa cells to duplicate and the granulosa cells create estrogen again
causing estrogen to surge and FSH + LH and GnRH to be low (inhibited
late follicular phase
ovulation
Fimbriae
Fallopian tube: passage for sperm and oocyte
ovary: oogenesis + hormones
uterus: site of the implantation
cervix: entrance to the uterus
vagina: site of sperm deposition, removal of menstrual fluid
luteal phase
(after ovulation)
lining of uterus gets thicker
female reproductive organs
female anatomy
uterine events: hormonal changes
anterior pituitary hormones
follicle changes
ovarian hormones: estrogen, progesterone
uterine changes
uterine phases
x-axis
menses, proliferative, secretory phase
overview of menstrual cycle
follicular phase
~1-7 menstruation (least fertile)
~8-9 possible to conceive
~10-14 ovulation the fertile window (best chance of conception)
luteal phase
~15-16 possible to conceive
~17-28 thickening of uterine lining (unlikely to conceive)
pre-menopause & menopause
- loss of primary follicles means less estrogen
- less estrogen means levels are so low that we lose the negative feedback effect
- FSH and LH levels rise drastically, causing strange fluctuations in primary follicle recruitment, and estrogen levels
- pituitary becomes exhausted, LH and FSH levels drop
- cycle ends, and menopause is reached
- begins to happen between ages 45-55
- symptoms include hot flashes, loss of fertility, changes in bone health, metabolic changes etc..
sex steroid hormone effects
- follicular development (estrogen)
peripheral (endocrine) effects:
- uterine changes (estrogen & progesterone)
- feedback (negative/positive)
- cardiovascular health
- bone density
- breast changes
etc. .
birth control: hormone changes
combination pill containing both estrogen and progesterone - taken for 21 days, followed by 7 placebo pills
keeps estrogen at levels that negatively feedbacks to the hypothalamus and the anterior pituitary
main mode of function to prevent fertilization is the cervis. The levels of progesterone keep cervical mucus in a thick, barrier state
can affect libido
birth control: hormonal IUD
intrauterine device - inserted by a physician
releases low dose of progesterone
affects uterine lining and affect cervical mucus
does not affect ovulation
lasts about 5 years
reproductive conditions
endometriosis
- endometrial like tissue
- outside endometrium affecting 10% of women
- when blood touches these sites, they become inflamed and painful
journey to fertilization
vaginal canal is acidic and sperm cells die and release alkaline fluid which allows other sperms to stay alive
head
- nucleus
- acrosome
tail
- neck
- middle piece
- principal piece
- end piece
ejaculate: 15 million/ml-200 million/ml
reach the ovum: 50-100
fertilization: 1
fertilization
ovum surrounded by cumulus cells (former granulosa cells) and zona pellucida
- get to cumulous cells and break through using hyaluronidase
- reaches zona pellucida & binds to oocyte membrane
- acrosome reaction triggered
- fuse with plasma membrane
- block polyspermy (cortical reaction)
creating the zygote
- head enters cytoplasm of ovum
- meiosis II completed: polar body forms
- two nuclei fuse (diploid)
- zygote is created
- rapid cell dividsion (mitosis) begins
per-implantation development
zygote → 4-cell stage → morula → blastocyst (day 5 post-fertiliztior)
→ trophoblast cells (inner cell mass) - aid in implantation of attaching to uterin lining
implantation of blastocyst
trophoblast cells (blue cells)
inner cell mass (yellow cells)
trophoblast cells digest endometrium (create lacunae) trophoblast enters uterus lining
placental development
placenta
lacunae
chorionic villi
amniotic fluid
clinical correlates: placental anomalies
placenta accreta: invades past the endometrium to the myometrium
placenta percreta: invades past the uterine wall, and attaches to other organs
placenta previa: covers the cervical opening
twinning
twins from two zygotes = dizygotic (fraternal if boys, soraral if girls)
twins from one zygote = monozygotic (identical)
labelling twins: twin A is closest to the cervix and will be born first if it’s a vaginal birth; twin B is implanted higher up in the uterus and would be most likely born first if it is a C-section
mono- & dizygotic twins
twins that come from one egg that splits is called monozygotic and are identical
twins can come from two different eggs, that have each been fertilized, which creates two different zygotes. non-identical
early development of zygote
zygote starts to multiply by mitosis → morula → blastocyst (day 5 post-fertilization)
trophoblast cells (placenta)
inner cell mass (baby)
pregnancy
pregnancy: 40 weeks (280 days) after Last Normal Menstrual Period
38 weeks (266 days) after fertilization
preterm birth (prematurity): born before 34 weeks
gestation
gestation: 40 weeks (280 days)
nearly every organ system needs to change to accommodate this growing baby
- joints and muscles
- endocrine system
- cardiovascular system
- renal system
- respiratory system
placenta
- attach developing baby to mon
- lots of exchange
- hormones produced
- arteries and veins resting in the maternal blood
endocrine adaptions
- trophoblast cells make high levels of HCG (Human chorionic gonadotropin)
- eventually the placenta starts making it’s own progesterone and doesnt need the trophoblast to make HCG
delivering the baby
hormone:
relaxin: causes the joints around the pelvis to relax and the cervix to dilate
- can affect other parts of the body, including feet
progesterone: prevents early contraction of the uterus, strengthens pelvic wall muscles
pituitary and pregnancy
anterior pituitary
- prolactin increases - triggers breast tissue to begin producing milk
first few days - produces colostrum “liquid gold”
posterior pituitary
- oxytocin increases - causes stronger uterine contractions - positive feedback loop. The stronger the contraction, the more oxytocin is produced
cardiovascular changes
- increase in blood volume
- increases in CO
CO = HR x SV
MAP = CO x TPR
vasodilation (decreases resistance to flow)
hypertension - blood pressure that is higher than 140/90
severe hypertension - blood pressure > 150/110
hypertestion is one of the most common complications of pregnancy
renal adaptions
- increased GFR
- increased filtered load
- increased RAAS
angiotensinogen turned into → angiotensin 1 by renin
angiotensin 1 turned into → angiotensin 2 by ACE
angiotensin 2 stimulates aldosterone to be released from the adrenal glands
respiratory changes
mom is breathes for two
- increase in alveolar ventilation
- increase in tidal volume
- decrease in residual volume (reduced dead space)
- increased PO2 and decreased PCO2
- respiratory alkalosis
developmental horizons
nervous system begins forming → 2-3 weeks
heart begins to form → 2-3 weeks
taste buds appear → 7 weeks
arms, legs, fingers, toes, eye, nose → 10 weeks
swallowing → 10 weeks
urination → 12 weeks
respiratory movements → 14-16 weeks
sucking movements → 24 weeks
vocalization → 24-26 weeks
light sensitivity → 28 weeks
11 weeks old - all major organ systems have already started to form. organs now must mature
- folic acid is required for normal neural tube development (the spinal cord and associated tissue), and to prevent spina bifida
- recommendation: women in their child-bearing years, and are sexually active, should be taking folic acid supplements
period of susceptibility
0-3 weeks: death of embryo may occur
3-8 weeks: formation of organs → malformation of embryo may occur (e.g. heart defect)
8-38 weeks: growth and maturation of organ systems → functional disturbance of fetus may occur (e.g. mental deficiency)
fetal growth
1st trimester: organ development
2nd trimester: length development
3rd trimester: gain weight
