Reproductive system Flashcards
Why we have a tendency for declining reproductive health?
The number of chemicals registered
for commercial use now 30 percent increase since
1979.
Exposed through industrial releases, contaminated food, household products and cosmetics, and the workplace • Coinciding with this rise are increased rates of infertility, decreasing sperm counts and higher rates of birth defects
Increase in progesterone during pregnancy can lead to
Hypospadias
Hypospadias is a common variation in fetal development of the penis in which the urethra does not open from its usual location in the head of the penis.
Hypospadias ( apart form progesterone can be caused by)
Phthalates and BPA are found in toys, food containers, cosmetics, and many other consumer products. PBDEs are used as flame retardants in household furniture and electronics
Plastics
of couples are infertile and infertility is
increasing due to reduced sperm counts, exposure
to environmental toxicants, obesity and delayed
parenthood
15-17%
How many men are recognized infertile with a cause
4%
Who is born more in the last 30 years
girls
What is happening with a sperm
Numbers are declining, as well as quality, 85% if sperm produced in a men is DNA-damaged
Where the spermatogenesis happen
In testes, more specific in seminiferous tubule
What is the structure of seminiferous tubule
On the periphery there are spermatogonium, which are immature sperm cells .
Specific cell types:
Sertoni-support spermatogenesis and respond to FSH, nourishment and nursing
Leydig cells - outside the tubule, respond to LH,secrete testosterone
Stages in spermatogenesis
On the periphery there are spermatogonium, which are immature sperm cells . As they move towards the center they undergo different stages of meiosis and then when they are near the lumen , they will receive the tails, and now sperms
Spermatogonium divide by mitosis and one of the cell is selected to produce primary spermatocyte (the other stays as a sem cell and is continued to divide by mitosis), then after meiosis I it becomes secondary spermatocyte, then mitosis 2 ->spermatids-> receive tails->spermatozoa
Oocytes can only contain____
x chromosome
n=23
Recall meiosis
Meiosis I: involves the separation of homologous chromosomes and recombination • Meiosis II: involves the separation of sister chromatids
Structure of spermatozoa
Head (where the genetic material is found), on the tip in acrosome that contains enzyme to digest the layer of oocyte
The midpiece, where a lot of mitochondria is found to propel the tail
and tail (flagella)
describe the pathway of hormonal regulation of spermatogenesis
GnRH ( gonadotropin release hormone) in hypothalamus activates the secretion of FSH from anterior pituitary and LH form posterior
FSH is going to bind sertoli cells, and by second messengers activate spermatogenesis
LH is going to stimulate Leydig cells,->release of testosterone
Testosterone will bind to androgen-binding protein (ABP), that was produced under FSH stimulation and promote spermatogenesis, as well as testosterone will have the effect on secondary male characteristics , and stimulate sertoli cells
When FSH activates the pathway of spermatogenesis, it produces also inhibin that will stop the secretion of FSH from pituitary
Testosterone will feeback GnRH and LH secretion
Is testicular cancer is treatable
Relatively yes
Two main parts of the uterus
The cervix and the body of the uterus
Also have fundus of uterus, follopian tibes, ovaries
Connection of ovary and follopian tubes is called
Infundibulum of the uterine tube
Where fertilization usually occurs
isthmus-Ampulla junction of uterine tube
Connection of the tube to the body of uterus
Isthmus
What is ectopic pregnancy
Ectopic pregnancy—development of the fetus in a place other than the
uterus- 95% in the fallopian tubes
When the girls is born what does she have already
All oocytes in meiosis 1
What happens at puberty with oocytes
Under the influence of FSH, they are going to grow from primary follicles->secondary follicles->graffian follicle (mature) and then ovulation, the follicle is arrested in meiosis 2
What will happen with cell development of oocyte with conception
It will undergo meiosis 2
The ovaries are endocrine
organs that secrete
the female sex hormones
(____)
estrogens and progesterone
Each uterine tube has three divisions
isthmus, ampulla, and infundibulum.
3 layers of uterus
endometrium
myometrium (mascular layer)
perimetrium ( the outter layer)
Histology of oviduct
Ciliated columnar cells
What is pelvic inflammatory disease
sexually transmitted
diseases can cause scarring and infertility
Destruction of cells lying the oviduct, lacking cilia-> may result in ectopic pregnancy
If a pelvic infection occurs in the tubes this can block the
passage, scar tissue, pus outside the tube can spread the
infection to other organs
• Cause of 1 in 4-ectopic pregnancy
• Pain upon palpation, may be discharge, fever some pelvic
discomfort
What is menstruation
spongy uterine wall
breaks down. The degenerating tissue,
blood, and unfertilized egg are passed
out as menstrual flow. Lasts 4-7 days
Stages in menstrual cycle
Follicular Stage -
Ovulatory phase
Luteal phase
How control pill work
A spike in LH is the key to induce
ovulation. Constant high levels of
estrogen (eg. Birth control pill) block the
LH surge and block ovulation.
Explain follicular phase
Day 1 - bleeding. at the same time FSH causes several ‘follicles’ to rise on the surface of the ovary. These fluid filled “bumps” each contain an egg. Eventually, one of these follicle becomes dominant and within it develops a single mature egg; the other follicles shrink back. If more than one follicle reaches maturity, this can lead to twins or more. The maturing follicle produces the hormone estrogen, which increases over the follicular phase and peaks in the day or two prior to ovulation. The lining of the uterus (endometrium) becomes thicker and more enriched with blood in the second part of this phase (after menstruation is over), in response to increasing levels of estrogen. High levels of estrogen stimulate the production of gonadotropin-releasing hormone (GnRH), which in turn stimulates the pituitary gland to secrete luteinizing hormone (LH). On about day 12, surges in LH and FSH cause the egg to be released from the follicle. The surge in LH also causes a brief surge in testosterone, which increases sex drive, right at the most fertile time of the cycle.
Explain ovulatory phase
The release of the mature egg happens on about day 14 as a result of a surge in LH and FSH over the previous day. After release, the egg enters the fallopian tube where fertilization may take place, if sperm are present. If the egg is not fertilized, it disintegrates after about 24 hours. Once the egg is released, there is a left over of the follicle which is called the corpus luteum
Peak in FSH and LH
Describe luteal phase
After the release of the egg, levels of FSH and LH decrease. The corpus luteum produces progesterone with the sti,ulation of LH. If fertilization has occurred, the corpus luteum continues to produce progesterone which prevents the endometrial lining from being shed. If fertilization has not occurred, the corpus luteum disintegrates, which causes progesterone levels to drop and signals the endometrial lining to begin shedding
If pregnancy occurs the embryo produces the pregnancy recognition hormone hcg ( human chorionic gonadotropin) this maintains the CL and progesterone levels which prevent a return to the estrous cycle
Inhibin role in menstrual cycle
Inhibin is secreted by the maturing follicle
In the first half of the cycle moderate
Estrogen levels and inhibin instructs the
pituitary to inhibit FSH (through a
negative feedback mechanism
Meiosis in developing the egg
Mitosis which is completed before birth oogonium is divided into anothe oogonium anf primary oocyte (2n) which later will enter meiosis
Primary oocyte undergoes prophase of meiosis I ( before the birth) that’s how they are arrested until puberty (2n)
At puberty , when the follicle is selected to mature it will continue the meiotic division
primary oocyte will form secondary oocyte (n) and first polar body (n)- it may divide , but will nit a mature egg
Primary oocyte will continue division until it becomes mature ovum ( if only fertilized)
The difference between meiosis in men and females
males -4 sperm with n
1 primary egg
Lifestage of gametogenesis in male and female
Male-begins at puberty
Female- begins with mitotic division before birth, resumes at puberty
Frequency of occurrence of gametogenesis in male and female
Male-constant after puberty
Female-monthly from puberty until menopause
What is the mechanism of combined birth control pills
Synthetic estrogen and progestin
Combined oral contraceptive pills were developed to prevent ovulation by suppressing the release of gonadotropins. … Estrogen negative feedback on the anterior pituitary greatly decreases the secretion of FSH, which inhibits follicular development and helps prevent ovulation
Minipill action principle
It keeps progesterone at the same level
inconsistently inhibit ovulation in ~50% of cycles and rely mainly on their progestogenic effect of thickening the cervical mucus around the cervix, thereby reducing sperm viability and penetration
•Why synthetic hormones? in birth control
Natural hormones are broken
down by the liver very rapidly
What are implants and patch contraceptives
Implants ex Implanon, release P last up to 3 yrs
• Patch change 1X a week, release E and P
What is PCOS
Endocrine disorder, common cause of infertility due to anovulation • Incidence is 1/10 • PCOS-follicles develop but do not ovulate- cystic follicles • More than an ovary issue as associated with metabolic disruption and high risk of developing type 2 diabetes
Symptoms of PCOS
Prevalence of hirsutism , acne , androgenic
alopecia , menstrual disorders ,
overweight , obesity , and infertility
Can go hand in hand with hypothyrodism
Hormonal disruption in PCOS
highly irregular
cycles, elevated testosterone, abnormal
FSH, LH, and excess Conversion of T to
DHT
How to diagnose PCOS and treat
blood tests, ultrasound
• Treatment: contraceptive pill, surgery,
Weight loss, exercise, diabetes
medication metformin
___ (time) for sperm to reach the egg in the
ampulla
5-10 minutes
How propulsion of sperm is achieved
Transport of the sperm is aided by mucosal
secretion, prostaglandins in the seminal fluid
from prostate stimulate contractions of the
uterus, a few hundred to thousand sperm
reach the ampulla
What happens in conception
Sperm must penetrate corona radiate
(granulosa cells), then bind and penetrate the
zona pellucida
• One the sperm has entered, MII is completed
and second polar body is extruded
What is an acrosome reaction
Once the sperm binds to the ZP it releases acrosomal contents (acrosome reaction)-proteases • This permits its entry into the perivitelline space then egg • Calcium rapidly rises by stimulating Phospholipase C, activates the egg • Block to polyspermy involves changes to ZP to prevent other sperm from entering egg
How long can the gg last
24 hours after ovulation
Do eggs age? Why are there greater risks with maternal
age?
More errors in division
Eggs are exposed to anything we put in
Aneuploidy is
of 1500 first trimester miscarriages 61% have
abnormal chromosome. It is the most frequent cause of
miscarriage and the risks of aneuploidy increase as women
age.
How many percent of embryos will miscarry after implantation
And in IVF?
31%
70%
What happens after fertilization
After fertilization within 3-5 days the zygote travels to the uterus.
• Aided by the cilia which always beat towards the uterus
• Rapidly increasing P from CL binds receptors on the smooth muscle
cells of the fallopian tubes and causing a relaxing effect promoting
entry of the egg into the uterus.
• On entry into the uterus called a blastocyst
8 vell zygote is called
morula
• Morula—solid mass of cells formed from zygote; takes approximately 3 days;
continues to divide
prenatal period is
Begins with conception and continues until the birth of a child
Parts in blastocyst
Trophoblast which will form the placenta
Inner cells - that will form the fetus
and blastocyst cavity
What is a cleavage
Mitotic division of zygote
What is a blastocyst
Blastocyst—by the time developing embryo reaches uterus
• Implants into uterine lining
• Approximately 5-7 days pass from fertilization until implantation in uterine
lining; can detect hcg (day 20-22)
Integrin secreted when
Integrin expressed on epithelium in window of implantation-at
time of implantation-day 10 or in late secretory phase nonpregnant
day 21
Plays role in implantation
Placenta is and important for
Acts as a barrier between the mother and the baby
Anchors fetus to uterus and provides “bridge” for exchange of nutrients and waste products between mother and baby • Also serves as excretory, respiratory, and endocrine organ • Placental tissue separates maternal and fetal blood supplies • Has important endocrine functions—secretes large amounts of human chorionic gonadotropin (hCG), which stimulates the corpus luteum to continue its secretion of estrogen and progesterone
Organization of the mature placenta
In humans, fetal chorionic epithelium is bathed in maternal blood because chorionic villi have eroded through maternal endothelium • Classification-Hemochorial
Gestation period: length, how it is divided
period—approximately 39 weeks; divided into three 3-month segments called trimesters • Embryonic phase extends from fertilization until the end of week 8 of gestation • Fetal phase—weeks 8 to 39
What is the role of relaxin
To relax joints, to make them more flexible
What is thought to be one of the major onset of labor
Fetal cortisol
How hormones change before child’s birth
Progesterone blocks uterine contractility this drops
before labor
Fetus pituitary secretes oxytocin, fetal adrenal glands
secrete cortisol, membranes release PGF-all can act to
increase intensity of uterine contractions
Irritation of or stretch of cervix-increase oxytocin
Stages of labor
Stage one —period from onset of uterine contractions until cervical dilation is complete Stage two —period from maximal cervical dilation until the baby exits through the vagina Stage three —process of expulsion of the placenta through the vagina
Birth is controlled by __ feedback
Positive
More uterine contractions-> more cervical stretch->more oxytocin from posterior pituitary ->prostaglandins from uterine wall-> more uterine contractions
Environmental exposures and reproductive health
Deodorants, bodycream, perfumes
accumulation of lipophylic chemicals (DDT/DDE-pestisides)
Inhalation exposure (plasticisers,heavy metal)
some in the breast milk (lipophylic)
oral exposure (plastics, food contamination)
What is the trend on sex of the babies born
Twice as many girls as boys are being born in remote communities North of the Arctic
Circle (2:1)
• Across much of the Northern hemisphere in US and Japan the gender ratio has skewed
towards girls
