Transcript The Reproductive System - Calgary Christian School

Unit 2
Reproduction and
Development
http://www.youtube.com/watch?v=_7rsH2lo
IY8
Crash course 12 min
Concept 1
Humans and other organisms have
complex reproductive systems; a gift from
the Creator to produce new life.
http://www.faithit.com/john-mark-comerbiblical-talk-sex-purity-beautylove/#.UwwDwBcrjcE.facebook
A. Introduction
PRIMARY sex organs are gonads
Testes – male gonads that produce sperm
(sex gamete)
Ovaries – female gonads that produce egg
or ovum (sex gamete)
SECONDARY sex organs are other
characteristics that separate males from
females (see text page 479)
Primary Sex Characteristics
What a person is born with
Secondary Sex Characteristics
What develops at puberty
Fertilization
During sexual intercourse (copulation or
coitus), the sperm and egg (each have
23 chromosomes) unite
This is called fertilization
Produce a zygote with 46 chromosomes
One of the chromosomes from each parent is
called sex chromosomes because it
determines the sex of the fetus
Male = XY
Female = XX
**Male determines the sex of the offspring
B. Anatomy of the male
reproductive system
1) Glands
 Testes – descend at birth
 produce the sperm cells in the seminiferous tubules
 Produce testosterone in the interstitial cells
 Seminal Vesicles – produce a fructose sugar
solution which makes up part (60%) of the
semen and nourishes the sperm, also
produces prostaglandins which stimulate
uterine contractions to help move the sperm
to the egg
Prostate Gland – produces an alkaline (basic)
solution of sodium bicarbonate which makes up
part of the semen, it protects the sperm from
the acidic nature of the vagina and activates the
sperm to swim
Cowper’s (Bulbourethral) Gland – produces
a mucous rich fluid that cleans the urethra
before ejaculation; may contain enough sperm
to get a women pregnant
2) Structures
Scrotum – a pouch of highly elastic skin that
holds the testes outside the body. Sperm
production is optimal at 2°C lower than body
temperature. Can move up and down
depending on body temperature
Seminiferous Tubules – tightly packed
tubules in the testes; site of spermatogenesis
Epididymis – site of sperm maturation
and storage (20 days approx.); located
just outside of the testes
Vas Deferens – tiny tubes that convey
sperm from the epididymis to the urethra;
these tubes are cut and tied off during a
vasectomy
Ejaculatory Duct – regulate movement of
sperm into the urethra
Urethra – carries both urine and semen (sperm
and glandular fluids) out of the penis; a
sphincter muscle insures that both aren’t
excreted at the same time.
Penis – male secondary sex organ covered by a
prepuce or foreskin which may be removed
(circumcision)
Direction of sperm travel
Testes 
Epididymus 
Vas deferens 
Urethra
http://www.youtube.com/watch?v=MOaL93xoHRk&feature=fvw
Vasectomy video
3) Spermatogenesis
Spermatogenesis – production of
sperm from specialized cells called
spermatogonia (primary spermatocytes)
which line the seminiferous tubules
Sertoli cells (support cells) nourishes the
developing sperm cell since they have
little cytoplasm
Chromosome numbers
The primary spermatocyte (46
chromosomes) undergoes Meiosis I to
produce 2 secondary spermatocytes
(23 chromosomes each). Meiosis II will
result in 4 spermatids which move to
the epididymus to mature into fully
functional sperm


http://wps.aw.com/bc_martini_eap_4/40/10469/2680298.cw/content/index.html
Spermatogenesis animation
Spermatogenesis
1° spermatocyte
(46 chromosomes)
Meiosis I
2° spermatocyte
(23 each)
Meiosis II
Sperm (23 each)
Sperm Structure
3 Distinct Parts:
The Head – contains the acrosome (has
enzymes used to digest through the outer
layer of the egg) and the nucleus
(contains the chromosomes)
Midpiece – contains mitochondria for the
production of ATP for movement
The Tail – flagellum used for movement
Ejaculation
Sexual excitement causes the arterioles in
the erectile tissue of the penis (corpus
cavernosum and corpus spongiosum) to
dilate and the venules to constrict
Causes the erectile tissue to become
engorged with blood under severe
pressure
 Erections are controlled by the parasympathetic NS, however, the
sympathetic NS is responsible for orgasm
 An erection is controlled by a reflex arc involving the spinal cord
Note: males with spinal injuries may still get erections because the
erection can be a reflex response
http://www.youtube.com/watch?v=gAnMymnJiLM
THE great sperm race
C. Anatomy of the female
reproductive system
1) External Structures
 Labia majora – outer fold of skin
containing pubic hair and sweat glands
(protection from foreign invaders)
 Labia minora – inner fold of erectile
tissue that is stimulated during sexual
activity. Its anterior portion encloses the
erectile clitoris (antibacterial immune response
cells)
 Bartholin’s glands – produces lubricating
secretions at the base of the vagina for
intercourse.
2) Internal Structures
Ovaries – produces the egg cells
(oogenesis) and estrogen and
progesterone
Follicles – located in the ovary; present
at birth, each will develop into an egg
when puberty is reached; produces
estrogen
Corpus Luteum – follicle cells left in
the ovary after ovulation has occurred;
induced by LH to produce progesterone to
maintain pregnancy
If not, endometrium is shed
Fallopian Tubes (oviducts) – tubes that carry
the female ovum (egg) to the uterus
site of fertilization of egg
ectopic or tubal pregnancy results if the zygote
implants here rather than uterus.
The end of the oviducts consist of finger-like
structure (fimbrae) which partially enclose the
ovary, they sway to create a current to draw the
egg into the fallopian tube from the ovary
Uterus – internal organ used for growth and
development of offspring
Lined with three layers:
Perimetrium – elastic connective tissue
Myometrium – muscular layer of smooth muscle,
plays a role in the delivery of a baby
Endometrium
nutrient rich layer that supports fetus during pregnancy
Shed each month during menstruation
Cervix – muscular opening into the
uterus from the vagina.
Very susceptible to cancer
Cervical epithelial cells are swabbed from the
cervix during a pap test.
Cervix holds the baby in the uterus during
pregnancy and dilates during birthing process
to allow for delivery
Vagina – muscular tube extending
from the cervix to the outside of the body
Receives the penis during intercourse
Nerve endings are located on the lower 1/3
Passage for menstrual flow
Birth canal
Shape changes during sexual excitement
Breast
take nutrients out of the blood to make
milk. Ducts move the milk out of the body.
sucking stimulates the release of oxytocin
which stimulates the release of oxytocin which
stimulates the milk to be released
breast feeding helps to reduce the size of the
uterus
Path of unfertilized egg
Ovary 
oviduct 
uterus 
vagina
Tubal ligation
http://www.youtube.com/watch?v=d9N-PT4C164&feature=related
3. Oogenesis
Production of ova from the specialized
cells called primary oocytes. Support
cells called granulosa cells nourish the
oocyte as it develops.
1° oocyte (46 chromosomes) undergoes
meiosis I to produce one 2° oocyte and
one polar body (due to unequal division,
the polar body is smaller and may not live
long enough to divide again.)
2° oocyte (23 chromosomes) is released during
ovulation.
Meiosis II of the 2° oocyte in the oviduct will
result in one ootid and another polar body.
The ootid will mature into an ova
**Unlike spermatogenesis, oogenesis results in
only one gamete!
http://wps.aw.com/bc_martini_eap_4/40/10469/2680298.cw/content/index.html
Oogenesis animation AND comparison of Oogenesis and Spermatogenesis
Meiosis I
Polar body
1° oocyte (46 chromosomes)
2° oocyte (23 each)
Meiosis II
Ootid (23 each)
Polar bodies (3)
4. The Ovarian Cycle
What happens in the ovaries is controlled by
two pituitary hormones (FSH and LH):
Follicle Development – the follicles are
stimulated by FSH. As a result, the
primary oocyte undergoes meiosis I and
the ovary secretes estrogen.
Ovulation – due to the influence of LH, the 2°
oocyte ruptures from the ovarian follicle into
the oviduct. The left over granulosa cells form
the corpus luteum
Corpus Luteum Formation – newly formed
corpus luteum secretes estrogen and
progesterone; both are required to maintain
pregnancy. If fertilization doesn’t occur, the
luteum will degenerate forming a small scar.
The endometrium is shed.
Note: each ovary will normally release one
mature ova every second month (only
about 400 ova mature and are released
once a month from puberty to
menopause).
Ovulation clip – animation and capture live
http://www.youtube.com/watch?v=nLmg4wSHdxQ&feature=fvw
http://www.youtube.com/watch?v=2-VKgdhfNpY&feature=related
Thought lab 14.3
See textbook page 496 for reference
Concept 2
Reproductive success of organisms is
regulated by chemical control systems.
Disney’s menstruation video
http://www.youtube.com/watch?v=4kWR-rIKRe4&feature=related
A. The Menstrual Cycle
Starts at menarche (beginning of
puberty), ends with menopause, and
occurs about once a month
Average cycle is 28 days, however,
health and stress can affect length (20-40
days)
1) Flow phase – begins with the shedding of
the endometrium of menstruation due to
low levels of estrogen and progesterone
(days 1 – 5)
 Pre-Menstrual Syndrome (PMS) – irritable, emotional,
cramping, headaches and nausea
2) Follicular phase – starts with the
development of the follicle due to FSH
secretions. The endometrium lining begins to
thicken and estrogen levels increase
(days 6 – 13)
3) Ovulatory Phase – the 2° oocyte bursts
from follicle cells in the ovary
(day 14)
Some women feel ovulation – a pinching in the ovary region
http://www.youtube.com/watch?v=DUAe7XO921E
How to tell if you are ovulating
http://www.youtube.com/watch?v=GBoWBw2SLBM
When you are Ovulating with a Fertility Microscope
4) Luteal Phase – the granulosa cells
differentiate into the corpus luteum which
produces estrogen and progesterone for
the maintenance of the endometrium.
(day 15-28)
If the ovum is fertilized, hCG (human chorionic gonadotropin) is
also produced to maintain corpus luteum and sustain high
levels of progesterone
If the ovum is not fertilized and implantation does not occur, LH
levels decrease and the levels of progesterone and estrogen
decrease.
graph showing hormone levels in the
menstrual cycle
http://www.youtube.com/watch?v=nwo9
KSNwSjE
Putting it all together
http://www.pennmedicine.org/encyclo
pedia/em_DisplayAnimation.aspx?gci
d=000087&ptid=17
http://www.bbc.co.uk/schools/gcsebit
esize/science/aqa_pre_2011/human/ho
rmonesrev3.shtml
scroll down and click to see cycle
Menopause
Generally starts age 45-55
Hormone levels drop leading to
physiological changes such as mood swings,
anxiety, hot flashes and irritability
Reproductive organs and breasts atrophy
Vagina becomes dry and is prone to
infection
Skin thins, bone mass is lost, blood
cholesterol levels rise
B. Hormones Involved in
Reproduction
1) Initiating Hormones (gonadotropic hormones)
Hormone
Follicle Stimulating
Produced By
Anterior Pituitary
Hormone (FSH)
Lutenizing hormone (LH)
(in males sometimes called
interstitial cell stimulating
hormone (ICSH))
Anterior Pituitary
Action
Female: maturation of
follicle and production of
estrogen
Male: development of
seminiferous tubule and
sperm
Female: induces ovulation
with high levels of
progesterone, promotes
growth of corpus luteum
and estrogen production
Male: stimulates interstitial
cells of testes to produce
testosterone
2) Male Sex Hormone Function
Hormone
Testosterone
Produced by
Testes – interstitial cells
Action
Stimulates the
development of primary
and secondary sex
characteristics.
Inhibits FSH and LH.
Testosterone Functions
1) Increase muscle development
2) Influence the secondary sex
characteristics
-
facial and body hair
Growth of larynx
Increase in sweat and oil production
3) Stimulates spermatogenesis
4) Increases sex drive and aggression
Testosterone levels in the body are directly
controlled by the pituitary and hypothalamus
through negative feedback.
This feedback can be altered through the
abuse of anabolic steroids.
 http://videos.howstuffworks.com/science-channel/29251-kapow-superheroscience-muscle-genes-video.htm
Kapow Superhero Science: Muscle Genes

http://videos.howstuffworks.com/health/steroids-videos-playlist.htm?page=2#video-19260
(12 minutes approx)

http://www.youtube.com/watch?v=sj3De6s3ZjQ the man who’s arms exploded
3) Female Sex Hormone Function
Hormone
Produced By
Action
Estrogen
Ovary – follicle and corpus
luteum
Stimulates secondary sex
characteristics and
growth of the
endometrium, inhibits
FSH
*In males, produced by
adrenal cortex and testes in
small amounts
Progesterone
Corpus luteum, placenta
Cause endometrium
growth, stimulate
lactation, inhibits uterine
contractions and FSH
*In males, produced by
adrenal cortex and testes in
small amounts, precursor of
testosterone
4) Pregnancy Hormones
Hormone
Produced By
Action
Human chorionic
gonadotropin (HCG)
Chorion layer of embryo
(placenta)
Stimulates the corpus
luteum to keep working
(produces progesterone for
about 3 months)
Relaxin
Produced by ovaries and
placenta
Relaxes ligaments
between pelvic bones and
enlarges the birth canal
Oxytocin
Posterior pituitary (of
mother and fetus)
Causes strong uterine
contractions, stimulates
the “let-down” reflex in
breasts
C. Birth Control Pills
Tricks body into thinking its pregnant so
ovulation does not occur
Raises level of estrogen and
progesterone in body (exerts neg.
feedback on hypothalamus)
Hypothalamus stops production of
GnRH and the pituitary stops
production of FSH and LH
Without FSH and LH, no follicle develops and
no egg is released.
Endometrium lining is still produced and
maintained as usual
Pill is taken for 21 days of the 28 day cycle.
The last 7 days of the cycle are when the lining
will be shed in the flow phase.



http://www.youtube.com/watch?v=KsQgMhvkg4E&feature=related
http://www.youtube.com/watch?v=YAEq7_NTltk&feature=related
http://www.youtube.com/watch?v=xej01Wl9j8o&feature=related
birth control pills
Plan B
Catholic view on birth control
D. Sex determination
Sex of a person is determined
genetically at conception, but it doesn’t
manifest itself anatomically until week
8 of embryological development.
Sex may also be influenced by hormones,
temperature, metabolic rates, and Testes
Determining Factor.
E. Reproductive disorders
1) Menstrual cycle disorders – range






PMS (pre-menstrual syndrome)
Anovulation (menstruation without ovulation)
Dysmenorrhea (painful/difficult menstruation)
Menhorrhagia (excessive bleeding)
Amenorrhea (absence of flow)
Metrorrhagia (bleeding at irregular times)
menstrual disorders
http://www.youtube.com/watch?v=fXARmctvt_c
2) Inguinal hernia – result of membrane
rupturing and the small intestine
falling into the scrotum.
Causes temperature of testes to increase,
increased pressure, and restriction of blood
flow to either organs
 Inguinal Hernia Surgery Repair
http://www.youtube.com/watch?v=R6pwlIVQPVA
3) Impotency – inability to achieve an
erection due to psychological reasons
(stress, etc.) or physiological reasons
(nerve damage, hormone imbalance, etc.)
4) Male/Female infertility – may be due to a
lack of gamete production, blockage of
reproductive tract, insufficient godnadotropic
hormones, absence or malformation of part of
the reproductive tract
Male Infertility (Getting Pregnant #3)
http://www.youtube.com/watch?v=QdIl1TjUvIQ
5) Endometriosis – establishment of the
uterine lining tissue on the outside of the
uterus
6) Infections
Hydroceles (build up of fluid in scrotum)
Prostatitis (inflammation of the prostate)
Vaginitis (inflammation or irritation of the
vagina – ex. Yeast infection)
7) Cancer, polyps, cysts, and molar
pregnancies – abnormal growth of cells
8) Sexually Transmitted Infections (STIs) –
infections that affect sex organs and genital
areas. STIs are transmitted as a result of some
sort of intimate touching, usually sexual
intercourse. STIs are caused by specific
pathogens such as viruses, bacteria, fungi, etc.


Types of Sexually Transmitted Infections (10 min)
http://www.youtube.com/watch?v=Bazh6p5rOFM&feature=related
Syphillis
Caused by bacterium
Fatal if untreated
Early Symptoms: swollen lymph glands,
rashes, mouth sores, anal-genital sores
Later Symptoms: sore throat, bone pain,
fever, headaches, patchy loss of hair
Treated with antibiotics
If not treated, can attack NS and lead to
insanity and death
Gonorrhea
Caused by bacterium attacking urogenital tract,
the rectum, the joins, the brain, the
cardiovascular system, and the cervix
Transmitted through sex or birth
Symptoms: urinate often and it has a burning
sensation, pus discharge
Most women do not experience any symptoms
Scars may form that cause infertility
Treated with penicillin
Herpes
Caused by a virus
Simplex A-I causes cold sores
Simplex B causes VD in monkeys
Simplex A-II causes small painful blisters
on genitals
Symptoms come and go; there is no cure
but treatment reduces severity
AIDS (Acquired Immune
Deficiency Syndrome)
Caused by HIV virus
Passed through body fluids
Virus inserts its RNA and we produce its DNA
Initial Symptoms: Weight loss, swollen lymph
glands, persistent cough, may not show up for
years
Virus attacks immune system and person dies
from secondary infection like shingles, TB,
pneumonia, meningitis, and herpes
Genital Warts – human
pailloma virus (HPV)
Treatment – cryotherapy, liquid nitrogen,
laser surgery
No cure
May be an increased risk of cancer
Associated with cervical cancer, and tumors
of the penis, vulva, vagina and anus
Hepatitis B Virus (HBV)
Symptoms – jaundice, fatigue, abdominal pain,
loss of appetite, nausea, vommiting, joint pain
Transmission – blood or bodily fluids from an
infected person enters the body of someone not
immune, sexually transmitted
No cure, drugs can be used for treatment
Can be vaccinated to prevent infection
Hepatitis C
Viral
Same symptoms as Hepatitis B
Transmitted through body fluids
No vaccine for prevention
Hepatitis A
Not an STI
Same symptoms as Hepatitis B
Transmitted through household contact
with infected people (stool, poor hygeine)
Vaccine available
Chlamydia
Caused by bacterium chlamydia
trachomatis
Causes urethritis and PID (pelvic
inflammatory disorder) in males and
females
Can cause sterility
May be passed to infant during childbirth
Treated with antibiotics
Concept 3
Cell differentiation and organism
development are regulated by a
combination of genetic, endocrine and
environmental influences.
A. Fertilization and
Pregnancy
Peristaltic contractions, villi and currents sweep
ovum down towards uterus and the approaching
sperm
Fertilization (conception) occurs in fallopian
tube when one sperm fertilizes the egg (form
zygote with 46 chromosomes)
The oocyte is viable for 12-24 hours after ovulation
Sperm is viable for 12-48 hours after ejaculation
Sperm can survive inside a woman’s body for 6 days
It takes 1 to 2 hours for the sperm to travel to
the oocyte
The instant ONE sperm releases the
enzymes from the acrosome, the egg expands
its outer layer so no other sperm can
penetrate (layers called the corona radiata and
the zona pelluciada).
Within 12 hours, the zygote (with 23 pairs of
chromomsoes) begins to divide rapidly
through mitosis
Period from fertilization to delivery
(parturition) is called gestation
Gestation lasts ~39 weeks (humans)
This time frame is divided into three
trimesters of about 3 months each
B. Twins
Fraternal Twins – occassionally two (or more)
eggs are released and fertilized at the same
time
Identical Twins – single fertilized egg splits
into two (or more) cell masses. These twins
share same genetic make up.
Siamese Twins – when cell mass separates
partially, but not completely




http://www.youtube.com/watch?v=oe5AV8PcKBo&feature=fvw
http://www.youtube.com/watch?v=5aBhHfV1dDc&feature=related
http://www.youtube.com/watch?v=K57IcN9DWXo
Share a Body
twins in the womb
conjoined twins
Abigail & Brittany Hensel - The Twins Who
C. Prenatal Development
Developmental Stages:
1. Zygote (1-3 days)
2. Blastocyst (4-6 days)
3. Embryo (7-60 days)
4. Fetus (60 days- birth)
http://www.youtube.com/watch?v=aR-Qa_LD2m4&feature=related
D. Embryonic Development
After fertilization zygote divides
(cleavage) so that it can differentiate in
a process called morphogenesis
Early cleavage stage: zygote undergoes
rapid mitotic division with NO GROWTH.
Zygote is now called a morula.
Day 3 – morula enters uterus
Day 5 – cells of morula form a hollow ball that
secretes fluid into the centre of the mass.
This is called a blastocyst
Blastocyst has two cell layers:
Inner layer (inner cell mass) – form embryo
Outer layer (trophoblast) – form membranes that
surround and protect embryo (eventually develops into the
chorion, which develops into part of the placenta)
 http://www.youtube.com/watch?v=UgT5rUQ9EmQ&feature=related
Day 6 – Blastocyst implants onto the
endometrium of the uterus (implantation
is complete by the tenth to fourteenth
day)
Trophoblast starts to secrete human
chorionic gonadotropin (hCG) and will
continue to secrete it at a high level for two
months and then to a lower level for the next
two months
Visible Embyro
http://www.visembryo.com/baby/females
ys.html
http://www.youtube.com/watch?v=ARER
GD0neMI
 After implantation: inner cell mass of blastocyst starts to
change
A space forms between inner cell mass and the
trophoblast called the amniotic cavity
While the amniotic cavity forms, the inner cell mass
flattens and forms the embryonic disk
The embryonic disk begins to fold and form 3 layers in the
process called gastrulation. The formation of different
types of cells and tissues is called differentiation.
Ectoderm (outer layer) – forms NS, hair, skin, sweat
glands, teeth, etc
Mesoderm (middle layer) – forms connective tissue,
kidneys, gonads, muscle, bone, circulatory system, etc.
Endoderm (inner layer) – forms digestive tract,
respiratory tract, liver, pancreas, etc.
The process that enables a cell to develop a particular
shape and to perform specific functions is called
differentiation.
http://learningobjects.wesleyan.edu/gastrulation/animations.php?ani=3D
http://www.youtube.com/watch?v=iQrkbS
86DOg
Carnegie Stages
http://www.visembryo.com/
baby/carnegiestages.html
 The organs form between the third and eighth weeks
 During the third week, a thickened band of mesoderm cells
develops along the back of the embryonic disk
 Forming a structure called the notochord which will form the basic
framework of the skeleton
 The nervous system develops from the ectoderm located just above
the notochord
Cells along the surface above the notochord begin to thicken and folds
develop along each side of a groove along this surface
When the folds fuse, they become a tube, called the neural tube which
eventually becomes the brain and spinal cord
This process is called neurulation
Soon after, the heart forms, by the 18th day, the heart starts to beat
http://learningobjects.wesleyan.edu/neurulation/index.php
http://www.pennmedicine.org/encyclop
edia/em_DisplayAnimation.aspx?gcid=
000090&ptid=17
http://www.youtube.com/watch?v=vgCFP
AWMKcI
The fourth week of prenatal development is a
time or rapid growth and differentiation
Blood starts to form and fill blood vessels
Lungs and kidneys take shape
Arm and leg buds start to form
A distinct head is visible with evidence of ears, eyes
and nose
The embryo is 0.6 cm long
At this time, the mother’s menstrual period is approx. 2
weeks late (might begin to think they are pregnant)
During the fifth week, the embryo’s head is very
large compared to the rest of the body
Eyes begin to open (no eyelids or irises)
Cells in the brain are beginning to differentiate
Embryo is approximately 1.3 cm long
During the sixth week the brain continues rapid
development
Limbs lengthen and flex slightly
Gonads are starting to produce hormones that will
influence the development of external genitalia
 During the seventh and eighth weeks the embryo has
distinct human characteristics
Organs have formed
Nervous system starts to coordinate body activities
A skeleton of cartilage has formed
Eyes are well developed, covered by the lid
Nostrils are developed and filled with mucus
External genitalia are still forming (undifferentiated)
By the eighth week, the embryo is about the size and mass of a
paper clip
From this time on, the organs enlarge and mature and the
embryo is now called a fetus
http://www.youtube.com/watch?v=APkV40vUhWs&feature=related
Fetus or a baby?
Crash course – Embryology
https://www.youtube.com/watch?v=k_9M
TZgAhv0
We are just tubes

Structures that support the
embryo (form between the 3rd and
8th weeks)
I) Chorion – outermost layer that develops
finger-like projections (villi) that push into
the placenta, forms the fetal portion of the
placenta
II) Allantois – forms the foundation for the
umbilical cord, degenerates during the
second month
III) Amnion (amniotic sac) – filled with
amniotic fluid that prevents shock to embryo
and helps regulate temp, and allow movement
IV) Yolk Sac – provides food and blood to cells
of embryo. It is limited in humans and
degenerates and becomes part of the umbilical
cord as soon as placenta is formed
http://www.youtube.com/watch?v=hNZ72NW-w68&feature=related
Week 1-9 pregnancy
Chorion amnion
yolk sac
placenta
V) Umbilical cord develops from the allantois
and extends through endoderm
The veins and arteries of the placenta attach to the
blood vessels of the fetus
It contains two umbilical arteries to carry oxygen
depleted blood from the fetus to the placenta and
one umbilcal vein to bring oxygenated blood to the
fetus
VI)Placenta is fully formed by end of month 2.
Placenta is site of gas, nutrient, and waste exchange.
It acts as a barrier, and produces hormones (HCG,
estrogen, progesterone, and relaxin)
Placenta contains blood vessels from mother and
child, however no mixing of blood occurs
Summary diagram together
Linking blastocyst structures to fetal
 Fetal Circulation
The fetus’ lungs are not used for gas exchange
There is an oval opening between the right and left atrium
called the foramen ovale
There is also a shunt between the pulmonary artery and the
aorta called the ductus arteriosus that allows any blood
entering the pulmonary artery to be carried to the aorta
The venous duct receives blood from the umbilical vein, and
the umbilical vein carries blood from the mother to the fetus
http://www.youtube.com/watch?v=gHnFoWEVs7o&feat
ure=related
http://www.youtube.com/watch?v=QIFQxxjZRXI&feature=fvwrel
http://ymghealthinfo.org/content.asp?pageid=P01790
E. Trimester Development
First Trimester
Rapid and coordinated growth during first 30
days
Sex is genetically determined at conception
Gastrulation
Human features take form (eyes, ears, nose)
Heart develops (beats by day 18) as well as
all other organ systems
Arms and legs form
Develops sucking and breathing reflexes
Placenta and umbilical cord are fully formed
http://www.youtube.com/watch?v=KXRbV33J5qk&feature=related
How a baby develops during pregnancy
http://www.youtube.com/watch?v=R6KhgAhO9F0&feature=related
Weeks 10-14
http://www.youtube.com/watch?v=0685efom9Yk&feature=related
Weeks 15 - 20
http://www.youtube.com/watch?v=I-HMYRtquzA&feature=related
Weeks 21 - 27
http://www.youtube.com/watch?v=mXZddL6RYFU&feature=related
Weeks 28- 37
Second Trimester
Actively turns
Organs have all formed
Soft hair, eye lids and eye lashes form
Bone cells are fully developed
Wakes and sleeps like a baby
Respiratory system is last to develop; at end
of 6th month it is developed enough to sustain
life out of the womb
Third Trimester
Body increases in mass and length
Fat cells develop (BAT- brown adipose
tissue), maturation of lung tissue and other
organ systems
Immunity develops
Testes of male descend
Fetus: 4 Weeks
Fetus: 8 Weeks
Fetus: 14 weeks
Fetus: 24 Weeks
Fetus: 32 weeks
F. Influence of Environment
on fetal development
http://www.youtube.com/watch?v=XTh2-eWfcXI
1) Teratogenic Agents: drugs, viruses, radiation
 cause malformation in the fetus
 Destructive power is directly related to critical
growth periods of the fetus
Ex) Rubella (German measles) has severe effect of
fetus in first trimester but none in later
trimesters
Ex) Thalidomide is a drug given for morning
sickness that has severe effects on limb
development in first trimester
http://www.youtube.com/watch?v=3k6TwvSE
-iI
2) Maternal Habits:
Drug use: mothers using drugs (ex. Morphine or
cocaine) give birth to babies addicted to these
drugs; they are often underdeveloped and
below normal birth weight
Smoking: mothers who smoke have increased
risk of premature delivery, reduced birth weight,
and miscarriage. Nicotine and CO inhaled when
smoking reduces oxygen for fetus
Alcohol: FASD – Fetal Alcohol Spectrum Disorder
or FAS – Fetal Alcohol Syndrome
Fetal Alcohol Syndrome -The Biological Basis / FAS
FASD Video
http://www.youtube.com/watch?v=X9ap3
Iimimk
G. Labour (Parturition)
 Levels of estrogen and progesterone decrease
 Levels of Relaxin and oxytocin increase
 Relaxin – causes relaxation of pelvic ligaments which
widen the birth canal
 Oxytocin – causes stronger uterine contractions
Uterine contractions stimulates the release of oxytocin, which in
turn, stimulates further contraction of the uterine muscles,
which stimulates the production of more oxytocin and so on...
This is positive feedback.
http://www.youtube.com/watch?v=RIB5ko2y9uU&feature=related
 How pregnancy tests work (see next slide)
Uterine contractions indicate onset of
labour, they occur every 15-20 minutes
and last 40 seconds or longer
Amniotic sac may break and amniotic fluid
(along with the cervical plug) is released
(breaking of the water)
1) Stages of delivery
1st stage – dilation of cervix (nearly 10
cm). Can last 8-24 hours
2nd stage – regular contractions (every
1-2 minutes) and expulsion of fetus
(partuition)
If a baby is born breech – it means the baby
comes out buttocks or legs first
3rd stage – expulsion of afterbirth
(placenta)
Eating the Placenta
http://www.whattoexpect.com/
pregnancy/ask-heidi/eatingthe-placenta.aspx
Procedures Associated with
Stage Two of Delivery
 Inducing labour
http://www.youtube.com/watch?v=3Mt5iusB2Eo&feature=related
 Caesarian Section – low horizontal incision make through the lower
abdominal wall and lower portion of the uterus
http://www.youtube.com/watch?v=miFnKRQxs6g&feature=related
 Spinal Block – anesthetic is injected in the spine used only for a C-section
 Epidural – anesthetic is injected into the spinal column, works slowly
http://www.youtube.com/watch?v=1evFwMXnGiI
 Episiotomy – a surgical incision is made to enlarge the vagina to facilitate
delivery
2) Lactation (milk production)
Prolactin (from anterior pituitary gland) –
stimulates mammary glands to begin
making milk. When baby suckles on the
nipple, sensory nerve carries a message
to brain and pituitary to release oxytocin.
Oxytocin causes weak contractions of
smooth muscle in breast forcing milk into
the ducts that carry milk towards nipple
First breast milk (colostrum) contains
sugar and proteins (especially
antibodies), but no fat.
Later, milk has less antibodies and more
fat.
Genetic Testing
 http://www.youtube.com/watch?v=o8BVUgEnUSQ
Amniocentesis
https://www.youtube.com/watch?v=sxEf_d
dmpZk
CVT
 http://www.youtube.com/watch?v=DvcDXvlCXAE&list=P
LCAFB8ADBE244E60C
Fetal monitoring
 http://www.youtube.com/watch?v=slbeTHBFrrc
Ultrasound