Ch 10 - Conception & Fetal Dev Flashcards
Union between a single sperm and egg that marks the start of a pregnancy
conception
process of conception
gametogenesis
ovulation
fertilization
implantation
Process by which oocytes and spermatocytes are produced
Gametogenesis
When does oogenesis begin?
When does spermatogenesis begin?
oogenesis: during fetal life. When a female is born, she is born with all the eggs she will ever have (2 million, most of which degenerate, leaving only 400-500)
spermatogenesis: starting from puberty, continues into 80s and 90s.
Describe Ovulation
- what occurs
- hormones responsible for follicular rupture
- what occurs to make fraternal twins possible
Each month one ova matures and is released from its ruptured ovarian follicle
hormones responsible: LH, FSH. Occasionally, two ovum
are released, making fraternal twins possible
High levels of ________ increase the motility of the fallopian tubes so that the cilia are able to move the ova through the tube toward the uterus
estrogen
Most common site of conception
ampulla
If fertilization is to occur, it usually takes place in the _______ _______ of the tube
outer third
Ova are fertile for __ hours after ovulation. If fertilization does not take place in this timeframe, the ova breaks down and is reabsorbed.
24
Protective layers will need to be penetrated by sperm in order for fertilization to occur. This is able to occur when __________ from the ______ are released and aid in breaking down that protective coating of the ova
enzymes, sperm
Typical male ejaculation contains # - # million sperm & can live in a woman’s reproductive tract for # - # days
2-5 million sperm
2-3 days
Occurs when a sperm is able to penetrate the membrane surrounding the ova
At this time, both ova and sperm become enclosed in the membrane
fertilization
Progression of zygote to implantation
zygote –> 2 cell –> 4 cell –> morula (little mulberry) –> blastycyst/trophoblast/embryoblast –> implantation
eventually will be placenta
embryoblast
blastocyte
trophoblast
trophoblast
eventually will become embryo
embryoblast
blastocyte
trophoblast
embryoblast
whole structure of developing embryo
blastocyte
When the protective coating degenerates, trophoblast cells will displace the endometrial cells at the implantation site and the blastocyst embeds itself on the endometrium when uterus is at its most nourished
usually occurs in fundus endometrium w/in 6-10 days after conception
implantation
implantation in cervix
blocks baby’s passage
requires c-section
placenta previa
What will secrete enzymes to allow the fertilized egg to burrow into the endometrium and cover the blastocyst?
trophoblast
What occurs @ the site of implantation that makes implantation bleeding occur? - usually around the same time as the when a period might occur which makes women miss the first month of pregnancy
Endometrial blood vessels erode
conception - day 14
pre-embryonic
week 2 - 8
embryonic
Week 9 - birth
fetal
which period is the baby at greatest risk due to drugs, alcohol, trauma, malnutrition, smoking, lack of folic acid, measles?
what might these things cause?
Why is she @ greatest risk?
embryonic
spontaneous miscarriage or fetal development issues
mom doesn’t know she’s pregnant
When do people generally realize they’re pregnant?
6 weeks
What is the primary reason for barrier methods with pregnant women?
protection from STI
Develops into epidermis, glands, hair and nails, nervous systems, lens of the eye, tooth enamel, and floor of amniotic cavity
Ectoderm
Develops into bones, teeth, muscles, dermis, connective tissue, spleen, genitourinary, and cardiovascular system
Mesoderm
Lining of respiratory and digestive tracts, and the glandular cells of associated organs. Forms the roof of yolk sac.
Endoderm
which stage is most crucial for development and organogensis in babies?
rapid cell division occurs and most vulnerable to outside influences
By end of this stage, all organ systems are present, as well as external structures
Unmistakable human appearance by the end of this period - hands, feet, cardiac movement
embryonic
Covering of the FETAL side of the placenta. Contains the major umbilical blood vessels, attached to inside of uterus
chorion
Forms a fluid filled sac around developing embryo and covers the umbilical cord. Also covers the chorion on the fetal side of the placenta. Will enlarge with pregnancy to accommodate growing fetus
amniotic sac
greatest risk if amniotic sac is ruptured early?
chorioamnionitis
Why do you test amniotic fluid?
for genetics or see if lungs are matured → esp if you are induced at week 39
made up of fluid secreted by the respiratory and GI tract of the fetus, as well as sterile fetal urine beginning in week 11
what is the normal volume at term?
amniotic fluid
700-1000 ml
Functions of amniotic fluid
- temp
- F&E
- fetal movement
- cushion from trauma
- barrier to infection
- fetal lung dev
- prevent sticking
- fetal growth
- cushion for umbilical cord
- genetic studies/studies of lung maturity
Begins as connecting stalk that attaches amniotic sac and yolk sac to chorionic villi
Eventually will develop in stalk that supply nutrients and oxygen to embryo
Stalk gets compressed on both sides by amnion and results in …..
umbilical cord
# artery(ies) # vein(s)
2 arteries from embryo to placenta (w/ deoxygenated blood)
1 vein from placenta to embryo (w/ oxygenated blood)
What nasty thing is a protective covering over the umbilical cord?
wharton’s jelly
what 2 things result in decreased oxygenation and may contribute to fetal death?
compression
knotting