Transcript Pregnanc and Fetal Developmentx

Biology 30
Hormonal Control of Reproduction
Conception, Pregnancy,
Development, Birth
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Did You Know?
Whistling is rated
the number one
subconcious way
to attract the
opposite sex
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Hormonal Control of Reproduction
Male Reproductive System Control
Testosterone
Primary Function
Stimulate spermatogenesis
Secondary Function
Maturation of testes and penis
Sex drive
Facial hair
Body hair
Deeper voice
Increased muscle strength
Body oil secretion -- acne
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Hormonal Control of the Testes
 Hypothalamus releases
1. Gonadotropin-Releasing Hormone (GnRH)
 Stimulates pituitary to release LH & FSH
 Pituitary releases
1.
Follicle-Stimulating Hormone (FSH)
 Stimulates spermatogenesis by seminiferous
tubules
2. Luteinizing hormone (LH)
 Stimulates testosterone production by interstitial
cells
 Indirectly stimulates spermatogenesis because
testosterone is required for sperm production.
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Hormonal Control of the Testes
LH, FSH, and GnRH concentrations
in the blood are controlled by
negative feedback systems
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Testosterone production
Spermatogenesis
Testosterone production
Spermatogenesis
Believe it or not…
Simon (Sime-one), Tom Green,
Nick Fitio, (Calgary Flames)
John Kruk, (Phillies) Hitler
and Napoleon were
missing one testicle.
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Hormonal Control of Female Reproduction
 Hypothalamus - produces releasing GnRH
Anterior Pituitary – secrete gonadotropic hormones.
FSH - follicle stimulating hormone.
LH - luteinizing hormone.
Ovaries - secrete the female sex hormones.
Estrogen –thickening of uterine lining
Progesterone – matures/maintains uterine lining
Hormonal Control of Reproduction
FSH is released from AP
Start the ripening of ovum within
follicle
Estrogen is produced by
follicle
Development of endometrium for
possible pregnancy
Feedback to hypothalamus to
inhibit FSH and release LH
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Hormonal Control of Reproduction
LH surge on day 14
Stimulates ovulation
Conversion of follicle into corpus
luteum
Progesterone production
Continued development of
endometrium
Feedback to inhibit release of LH
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Hormonal Control of Reproduction
If no fertilization
Degeneration of corpus luteum
Drop in hormone level
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Menstruation
The four phases
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Four Phases of Menstruation
1. Flow Phase (Menstrual Phase)
 Start of bleeding marks Day 1 of
phase
 Shedding of the endometrium
(uterine lining)
 Average = 4-5 days
 Sometimes up to 8 days
 Occurs due to low hormone levels
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1
Four Phases of Menstruation
2. Follicular Phase
 Occurs during day 6-13
 Period of repair and thickening of
endometrium.
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Four Phases of Menstruation
2. Follicular Phase
 Occurs during day 6-13
 Period of repair and thickening of
endometrium.
 FSH from the pituitary promotes follicle
development in the ovary.
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Four Phases of Menstruation
2. Follicular Phase
 Occurs during day 6-13
 Period of repair and thickening of
endometrium.
WHY??
 FSH from the pituitary promotes follicle
development in the ovary.
 As follicle develops it produces estrogen,
 thickening of the uterine lining
 LH production increase
 FSH production decrease
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FSH
Decrease
Four Phases of Menstruation
3. Ovulation Phase
 LH causes ovulation to occur on
day 14.
 Secondary oocyte is released
from the follicle/ovary.
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Four Phases of Menstruation
4. Luteal Phase
 Final preparation of endometrium to
receive the fertilized ovum
 LH stimulates development of the Corpus
Luteum.
 causes progesterone levels to increase.
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Four Phases of Menstruation
4. Luteal Phase
 Final preparation of endometrium to
receive the fertilized ovum
 LH stimulates development of the Corpus
Luteum.
 causes progesterone levels to increase.
 Estrogen and progesterone inhibit GnRH,
thereby decreasing LH and FSH levels.
 This low level of hormones initiates the
flow phase.
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Menopause
The end of a woman’s reproductive years
Between ages of 45 – 55
Ovaries no longer respond to FSH & LH from
AP
Ovaries do not produce estrogen or progesterone
Marked by circulatory irregularities (hot
flashes), dizziness, insomnia, sleepiness,
depression
Hormone replacement therapy may help.
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Did You Know?
Lions will have sex
over 500 times
with one mate. This
is to ensure
fertilization.
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Fertilization
Pregnancy
Development
Birth
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Sperm
Did You Know?
Sperm travels at
.001 miles per
hour.
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3 Steps of Fertilization
1. Capacitating
 Acidic environment of the female
reproductive tract causes small pores to
open in the acrosome (“enzyme-loaded”
head) of the sperm
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3 Steps of Fertilization
1. Capacitating
 Acidic environment of the female
reproductive tract causes small pores to
open in the acrosome (“enzyme-loaded”
head) of the sperm
2. Acrosomal reaction
 Enzymes released from acrosome digest
the outer membrane surrounding the
egg cell
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Steps of Fertilization
3. Fertilization
 A single sperm cell fuses with the
plasma membrane of ovum
 Head passes into the cytoplasm
 Electrochemical reaction in egg
 Makes membrane impermeable to
other sperm
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Fertilization
 Fertilization must occur within a
very short window of opportunity.
 Egg is only fertile for 10 - 15 hours
 Sperm are only fertile for 48 hours
 Sex (copulation) must occur no
more than 48 hours before or 15
hours after ovulation
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NO KIDDING
Italian physicians promotes
having regular sex with the
same partner because it is
good for digestion. He also
states that having casual sex
with many partners can
cause indigestion.
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Pregnancy
If pregnancy is established, menstruation
does not occur.
Fertilized egg is called a zygote.
Once cell division brings the total cell count to
around 8, it is called a blastocyst.
Takes 3-5 days for blastocyst to travel
through oviduct to uterus.
Blastocyst must implant into endometrium
Occurs 2-4 days after reaching the uterus
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Zygote
Cleavage
Blastocyst
Pregnancy
During implantation, the blastocyst
produces a hormone called HCG
Human chorionic gonadotropin
Prevents degeneration of corpus luteum
Stimulates corpus luteum to increase
progesterone secretion
Maintains uterine lining
Prevents contractions
Pregnancy test detects HCG in the urine of
women.
“Turns the stick blue”
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Pregnancy
Tissue grows out from the embryo and
mingles with endometrium to form placenta
A disc-shaped organ
Size of dinner plate
Weighs less than 1 kg.
Contains maternal & fetal blood vessels
NO mixing of maternal and fetal blood!!
Diffusion of gasses, nutrients, & wastes
Continues production of HCG, estrogen,
progesterone
Maintains endometrium
Corpus luteum not needed – dissolves
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Pregnancy
Progesterone & estrogen have a
negative feedback effect on the
hypothalamus
No secretion of FSH
No secretion of LH
No new follicles mature
Embryo remains firmly attached
to placenta by umbilical cord.
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Pregnancy
Umbilical cord
Contains:
2 fetal arteries
Fetus to placenta
One fetal vein
Placenta to fetus
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Childbirth
 Also called parturition
 38 – 42 weeks from conception
 Average = 40 weeks
 Three stages of childbirth
1. Labour
2. Delivery
3. Afterbirth
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Childbirth
1. Labour
 Involuntary
 Rhythmic contractions of the uterus
 Causes cervix to open
 Diameter = 10 cm
2. Delivery
 Involuntary uterine contractions
 Conscious abdominal contractions
 Mother forces baby out through cervix
and vagina
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Childbirth
3. Afterbirth
 Immediately after delivery
 Blood vessels in placenta
contract
 Placenta separates from uterine
wall
 Expelled by muscle contractions
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Childbirth
Why??
Nobody totally knows.
Baby plays some role in the timing.
Progesterone decreases
Allows uterus to contract
Oxytocin from posterior pituitary
Stimulates stronger uterine contractions
Relaxin
produced by placenta
Causes ligaments of pelvis to loosen
Larger passageway for baby
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Scared of Childbirth??
Did You Know?
• Human birth control pills work on gorillas.
• Erotodromomania is the abnormal impulse
to travel to escape painful sexual
situations.
• Genophobia- Fear of sex.
• Heterophobia- Fear of the opposite sex.
• Erotophobia- Fear of sexual questions.
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But Did You Know That…
The bonobo monkeys use sex
(and/or sexual favors) to
placate members of their social
group instead of grooming.
They are one of the few species
of animals (humans being
another) that have sex out of
season and for fun.
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Lactation
During pregnancy, high levels of estrogen
and progesterone prepare the breasts for
milk production
Each breast has about 20 milk glands
Connect to the nipple by ducts
Breast enlarges during pregnancy in
preparation for lactation
Expulsion of the placenta causes the
mother's pituitary to secrete prolactin,
Initiates lactation
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Lactation
Prolactin inhibits the release of LH
menstrual cycle is suppressed in
nursing mothers
The high estrogen and progesterone
levels during pregnancy are thought
to inhibit release of prolactin
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Lactation
The first fluid formed by the mammary
glands is colostrum,
Thick
contains lactose and milk proteins,
lacks fat
after a few days, milk is produced
Oxytocin is released from
hypothalamus when infant suckles
Causes milk to be released from
mammary glands
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Biology 30
Yet to come…
Embryonic Development
Birth Control Technologies
STD Effect on Reproductive Systems
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Fetal Development
A blastocyst
embeds in the uterine wall
Consists of cells of the future embryo
Surrounded by a sphere of cells
Embryonic membrane (extraembryonic membrane)
Support the developing embryo
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Fetal Development
Amnion
Innermost embryonic membrane
Next to baby
Fluid-filled sac that cushions the
baby
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Fetal Development
Chorion
Outermost membrane
Part of the placenta
Secretes HCG
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Fetal Development
Umbilical cord
Connection between mother and
baby
Belly-button to placenta
Carries baby’s blood to and from
placenta
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Embryonic Development
Placenta (review)
A disc-shaped organ
Size of dinner plate
Contains maternal & fetal blood vessels
NO mixing of maternal and fetal
blood!!
Diffusion of gasses, nutrients, & wastes
Continues production of HCG, estrogen,
progesterone
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Embryonic Development
 A blastocyst undergoes gastrulation
 Series of cell movements and shape changes
 Produces an embryo with 3 cellular layers
1. Ectoderm
 Outer layer of cells
 Will become skin and nervous system
2. Mesoderm
 Middle layer of cells
 Skeleton, muscles gonads, kidneys, circulatory
system
3. Endoderm
 Inner layer of cells
 Liver, pancreas, lungs, lining of digestive tract73
Human Gestation
The 40 Week Journey
Human Gestation
1st Trimester
From fertilization to end of 3rd
month (0 – 13 weeks)
Zygote begins cell division as it
moves down oviduct
Becomes blastocyst and implants in
uterus
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Human Gestation
1st Trimester
Development of body organs
Heart starts beating by week 4
Week 7, testosterone begins to be
secreted if a Y-chromosome is present
This testosterone causes development
of testes.
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Human Gestation
st
1
Trimester
By week-8 all major structures of the
adult are present (in basic form)
Embryo is now called a fetus
Embryo is most sensitive during first
trimester
Due to rapid development
Sensitive to radiation and drugs
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Fertilization
6 weeks
7 weeks
8 Weeks
8 weeks
10 Weeks
11 Weeks
11 Weeks
14 Weeks
Human Gestation
nd
2
Trimester
Fetus grows rapidly
To about 30 cm
Quite active
Hair begins to develop
Cartilage of skeleton is replaced
by bone
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18 weeks
The Hand Picture
May 2, 2000
USA Today
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An Amazing Story -- Aug.19, 1999
Samuel Armas' tiny hand grips Dr. Joseph P.
Bruner's finger just as Bruner finishes
returning him to his mother's womb.
Bruner, director of fetal diagnosis and
treatment at Vanderbilt University Medical
Center (Nashville), was performing a cuttingedge procedure on the 21-week-old fetus.
The procedure on Samuel took about an hour.
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An Amazing Story -- Aug.19, 1999
Bruner and Samuel's parents hope the
surgery will alleviate the effects of spina
bifida, a disabling birth defect in one or
two of every 1,000 babies born.
Because fetuses undergoing this procedure
are so young -- Samuel could not survive
outside his mother's womb -- this kind of
surgery is gaining attention nationwide
from the medical community and the media.
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An Amazing Story -- Aug.19, 1999
During the procedure, surgeons remove the
uterus from the mother, drain the amniotic
fluid, perform surgery on the tiny fetus,
replace everything and put the entire
package back inside the mother.
Dr. Bruner said regarding the picture,
"The baby did not reach out," Bruner says.
"The baby was anesthetized. The baby was
not aware of what was going on."
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An Amazing Story -- Aug.19, 1999
Bruner says he saw the hand "sort of pop up in
the incision" on the womb, and he "reached over
and picked it up."
Samuel, now nearly 5 months old [may 2, 2000],
& is “developing normally and hitting his
monthly milestones. He smiles often and is nearly
sitting up on his own.”
It will take years to know how much difference the
surgery made, but Alex Armas [father] says he's
happy the photo has been seen by millions.
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Samuel
Armas
21 weeks
Human Gestation
3rd Trimester
Rapid growth of fetus
To about 53 cm
3-3.5 kg
Fetal activity decreases
Less room to move
Fully mature
Ready for birth
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Quick Review
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Quick Review
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Birth Control
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Birth Control
Sterilization
Most effective
In males vas deferens is cut off and sealed
Only effects sperm content of semen so
minimal side effects
In females tubal ligation or cutting of the
oviducts
Disadvantages of sterilization - hard to
reverse
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Quick Review
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Birth Control
"The pill"
A combination of estrogen and
progesterone given for 21 days of the 28
day cycle
Effectively shuts down FSH and LH
production so follicles do not develop.
Many of the early problems have been
sorted out but side effects possible
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Birth Control – barrier methods
Diaphragms, cervical caps, vaginal sponges, condoms
Condom
fits over the penis and prevents semen
from entering the female;
Diaphragm
which fits over the cervix and prevents
semen from entering the uterus
both of these methods are more reliable
when used in conjunction with a
spermicidal foam or jelly
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Birth Control – barrier methods
IUD
Inter-Utarian Device
placed in the uterus by a physician,
prevent implantation of the
blastocyst in the endometrium.
Best for women who have had one
pregnancy, middle to older and are
at low risk for STD’s
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Birth Control
"Natural family planning"
Requires knowledge of the day of ovulation
If known, can avoid the 4 days either side
of ovulation to account for unusually long lived sperm or eggs.
Women need exceptionally regular cycles
to be effective
"Basal" body temperature measurements
(T rises at ovulation), vaginal pH
measurements (more alkaline), mucus
thickness can help determine time
ovulation.
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Birth Control
"Morning after pill“
Most are essentially a controlled overdose of
normal birth control pills
RU-486 now distributed by Planned
Parenthood.
Blocks progesterone receptors causing uterine
lining to slough off taking embryo with it.
Many people have ethical problems with these
pills since they remove fertilized eggs.
 i.e. after "conception" has occurred.
“abortion pill”
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Reproductive Technologies
Ultrasound
the use of high-frequency sound waves to
visualize the fetus
Amniocentesis
a long needle is used to remove a sample of
amniotic fluid from the amniotic sac
surrounding the fetus,
fetal cells in the fluid are cultured for 2 to 4
weeks and then analyzed for chromosomal
defects and other genetic disorders
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Amniocentesis
Reproductive Technologies
Chorionic Villi Sampling (CVS)
a small sample of tissue is removed from the chorion,
the fetal part of the placenta.
Can be performed earlier in the pregnancy than
amniocentesis
results can be obtained within a few days
greater risk of spontaneous abortion from CVS than
from amniocentesis
ethical considerations: essentially all detectable fetal
disorders remain untreatable in the uterus, and many
cannot be corrected even after birth
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Reproductive Technologies
In Vitro Fertilization
ova can be surgically removed from a woman
whose oviducts are blocked
These are fertilized in a petri dish in a
laboratory
The resulting embryos can than be inserted
into the woman's uterus (or into a surrogate
mother's uterus)
Ethical considerations: post-menopausal
woman can now have children; in surrogacy,
who is the legal mother???
A-la Phoebe from “Friends”
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Sexually Transmitted Diseases
Sexually transmitted diseases are
transmitted from one person to another
primarily by contact of the genital organs
during sexual activity.
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Crabs
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Epididimitis
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Genital Warts
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Syphilis
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Gonorrhea
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Sexually Transmitted Diseases
Syphilis
caused by a spirochete bacterium.
The first symptoms of syphilis may go
undetected because they are very mild and
disappear spontaneously.
The initial symptom is a chancre;
usually a painless open sore that usually
appears on the penis or near the mouth,
anus, or on the hands.
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Syphilis
may go on to more advanced stages, including
a transient rash and, eventually, serious
involvement of the heart and central nervous
system.
The full course of the disease can take years.
Penicillin remains the most effective drug to
treat people with syphilis.
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Initial Chancre on Hand
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Sexually Transmitted Diseases
Gonorrhea
discharge from the vagina or penis
“Ooooze”
and painful or difficult urination.
The most common and serious complications occur in
women and, these complications include PID, ectopic
pregnancy, and infertility.
Historically, penicillin has been used to treat
gonorrhea, but in the last decade, four types of
antibiotic resistance have emerged.
New antibiotics or combinations of drugs must be used
to treat these penicillin resistant strains.
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Sexually Transmitted Diseases
Chlamydia
many cases involve no symptoms and therefore infected persons
may not seek medical treatment.
This infection is now the most common of all bacterial STD's,
with an estimated 4 to 8 million new cases occurring each year.
In both men and women
abnormal genital discharge
burning with urination
In women, untreated chlamydial infection may lead to pelvic
inflammatory disease,
one of the most common causes of ectopic pregnancy and
infertility in women.
Chlamydia
Many people with chlamydial infection,
however, have few or no symptoms of infection.
Once diagnosed with chlamydial infection, a
person can be treated with antibiotics
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Sexually Transmitted Diseases
Genital herpes
Affects an estimated 60 million Americans.
Approximately 500,000 new cases of this incurable
viral infection develop annually.
Caused by herpes simplex virus (HSV).
 painful blisters or open sores in the genital area.
These may be preceded by a tingling or burning
sensation in the legs, buttocks, or genital region.
The herpes sores usually disappear within two to three
weeks, but the virus remains in the body for life and the
lesions may recur from time to time.
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Sexually Transmitted Diseases
Genital herpes
Severe or frequently recurrent genital herpes is treated
with one of several antiviral drugs that are available
by prescription.
These drugs help control the symptoms but do not
eliminate the herpes virus from the body.
Suppressive antiviral therapy can be used to
prevent occurrences and perhaps transmission.
Women who acquire genital herpes during pregnancy
can transmit the virus to their babies.
Untreated HSV infection in newborns can result in
mental retardation and death.
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Sexually Transmitted Diseases
AIDS (acquired immunodeficiency syndrome)
First reported in the United States in1981.
It is caused by the human immunodeficiency virus
(HIV),
a virus that destroys the body's ability to fight off infection.
An estimated 900,000 people in the United States are
currently infected with HIV.
People who have AIDS are very susceptible to many
life-threatening diseases (called opportunistic
infections) and to certain forms of cancer.
Transmission of the virus primarily occurs during
sexual activity and by sharing needles used to inject
intravenous drugs.
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Sexually Transmitted Diseases
Genital warts
Caused by human papillomavirus,
a virus related to the virus that causes common skin warts.
Genital warts usually first appear as small, hard painless bumps in
the vaginal area, on the penis, or around the anus.
If untreated, they may grow and develop a fleshy, cauliflower-like
appearance.
Genital warts infect an estimated 1 million Americans each year.
In addition to genital warts, certain high-risk types of HPV cause
cervical cancer and other genital cancers.
Genital warts are treated with a topical drug (applied to the skin),
by freezing, or if they recur, with injections of a type of interferon.
If the warts are very large, they can be removed by surgery.
Done
Study for your exam
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