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NURB 360 OB - UNIT I - Genetic, Conception and Fetal Development: Part I

Terms in this set (87)

T/F: the passing on of familial traits begins when male & female reproductive cells form
True
what structure hold genes
chromosomes
units of heredity and contain information for specific traits, specific feature, and body functions
genes
purpose of this cell division: growth and development or cell replacement
mitosis
where to cells replicate each chromosome
in the nucleus
each daughter cell contains ___ chromosomes
46
This type of cell division produces gametes?
meiosis
in meiosis, each homologous pair of chromosomes receives ___ chromosome from mother and ____ from father
...
In meiosis, cells contain one of each of ____ pairs of chromosomes
23
when does meiosis occur?
in sexual reproduction (gametogenesis)
in gametogenesis, there are ___ successive meiotic divisions that result in ___ cells, each containing ___ chromosomes. (known as the haploid number of chromosomes)
2 divisions
4 cells
23 chromosomes
Oogenesis - (male/female)
spermatogenesis's - (male/female)
oogenesis - female
spermatogenesis - male
oogenesis results in
1 ovum
3 polar bodies
1st meiotic division of an oocyte in
graafian follicle
2nd meiotic division of oogenesis is completed if ovum is ____
fertilized
mature ovum contains haploid number of chromosomes: ____ single chromosomes and always an ___ ___ chromosome
22 single chromosomes and always an X sex chromosome ___
extra chromosomes produced by each meiotic division are carried away by ____ ___, which are eventually disintegrated
polar bodies
spermatogenesis occurs where?
seminiferous tubules of testes
spermatogenesis involves 2 meiotic divisions and results in ___ sperm, each with ___ single chromosomes and either an __ or __ chromosome.
4 sperm
22 single chromosomes
either and x or y chromosome
process by which sperm fuses with an ovum to form diploid cell or zygote
fertilization
where does fertilization occur?
in the outer third (ampulla) of fallopian tube
fertilization occurs within ___ hours of ovulation
12 hours
fertilization occurs within ___-___ days of insemination
2-3 days
process of changes in membrane surrounding ovum undergoes to prevent entry of other sperm once fertilization occurs
Zona Reaction
each reproductive cell carries ____ chromosomes, then nuclei fuse and chromosomes combine, restoring diploid number (46).
23
the ovum always contributes an (X/Y) chromosome?
X
the sperm can carry an __ or __ chromosome
X or Y
XX =
female
XY =
male
(male/female) partner determines the gender of the child
male
during ovulation ___ leaves the ___ and enters the fallopian tube
ovum leaves the ovary
____ ____ occurs as the zygote moves through the fallopian tube toward the uterus
cellular multiplication
transportation takes how long?
3 days
___ occurs when the zygote enters a period of rapid mitotic division
cleavage
___ is the 1st step in development of ALL multicelled organisms
cleavage
cleavage converts single-celled zygote into a multicelled embryo by ____?
mitosis
when zygote has subdivided into 8 cells
blastomere
inner layer which develops into embryo and embryonic membrane
blastocyst
outer layer of cells which develops into chorion
trophoblast
as zygote is propelled toward uterus (blastocyst/trophoblast)layer chooses implantation site
trophoblast
what is the most frequent part of attachment during implantation
upper part of the posterior uterine wall
when does implantation occur
7-9 days after fertilization
____ begins when oocyte is fertilized by sperm and continues until day 14
zygote
____ begins at day 15 and continues until the 8th week of gestation or until embryo measures 3 cm from crown to bottom
embryo
___ begins 8th week and continues until 40th week of gestation or birth
fetus
10-14 days after conception, homogenous mass of blastocyst cells differentiates into 3 primary germ layers, what are these layers?
Endoderm
Ectoderm
Mesoderm
which layer?
endoderm
inner layer
which layer?
ectoderm
outer layer
which layer?
mesoderm
middle layer
____ forms tissues associated with outer layers: skin, hair, sweat glands, and epithelium
ectoderm
brain and nervous system also develop from the ___?
ectoderm
the ____ forms structures associated with movement and support: body muscles, cartilage, bone, blood, and all other connective tissue; reproductive system organs and kidneys form from this layer.
mesoderm
____ forms tissues and organs associated with digestive & respiratory systems. Thyroid & parathyroid gland, are formed by endoderm also, liver, pancreas, and gall bladder arise from endoderm
endoderm
- develops from trophoblast
- contains chorionic cilli on its surface
- outer membrane that envelopes amnion, embryo, and yolk sac
chorion
____ becomes vascularized and forms the fetal part of the placenta
chorion
___ becomes the covering of umbilical cord and covers chorion on fetal surface
amnion
amniotic sac = ____ + _____
anmiotic sac
clear, yellowish fluid that surrounds and protects the fetus in the uterus
amniotic fluid
obstruction of urine flow, as in PotterSyndrome, results in ___? (<300ml)
oligohydraminos
excessive amniotic fluid surrounding the fetus
(Poly)hydraminos
when fetus does not swallow normal amounts of fluid, ____ occurs
hydraminos
_____ is associated with renal abnormalities
oligohydraminos
_____ is associated with GI abnormalities
hydraminos (polyhydraminos)
___ ____ aids in transferring maternal nutrients and oxygen which have diffused through chorion to embryo
yolk sac
T/F: yolk sac functions only during embryo stage
true
___ provides for exchange of nutrients and waste products between fetus and mother
placenta
the placenta develops by which month?
3rd
T/F: large particles such as bacteria can pass through the placenta
false; bacteria cannot pass through the placenta
maternal part of placenta arises from what? (beefy, red appearance)
decidua basalis
fetal side of placenta develops from what? (gray, shiny appearance)
chorionic volli
name the 4 placental hormones
-human chorionic gonadotropin (hCG)
-placental lactogen (hPL)
-progesterone
-estrogen
hCG is detectable in maternal blood as soon as implantation occurs,usually ___ to ____ days after fertilization
8-10
-Stimulates adjustments in the mother's metabolism, so that adequate protein, glucose, & minerals are available for developing fetus.
-Increases resistance to insulin, facilitates glucose transport across placental membrane, & stimulates breast development.
Human Chorionic Somatomammotropin (hCS)(hPL)
-Increases tubal & uterine nourishing secretions in order to provide nutrition for morula & blastocyst stages.
-Reduces contractility of uterus to prevent spontaneous abortion.
-At high levels converts endometrial lining into decidual cells in order to permit implantation of blastocyst.
-Prepares mammary glands for secretion of milk
progesterone
-Major estrogen secreted by placenta is estriol, while the ovaries produce estradiol.
-Measuring estriol levels is a clinical assay for placental functioning.
-Provide for expansion of uterus, breasts, & breasts glandular tissue.
-Increase vascularity & vasodilatation of villous capillaries of placenta.
estrogen
umbilical cord is made up of what?
1 large vein, 2 small arteries
arteries carry ____ blood and waste products from fetus
deoxygenated
the veins carries ____ blood and provides oxygen and nutrients to fetus
oxygenated
what is it called when the cord is wrapped around the fetal neck?
nuchal cord
white connective tissue that surrounds and separates the blood vessels
whartons jelly
identical v fraternal twins
fraternal = 2 sperm, 2 eggs
identical = 1 sperms, 2 eggs
dizygotic twins =
fraternal
monozygotic (____) twins
identical
what types of twins originate from division of fertilized ovum at different stages of early development
identical twins
Foramen ovale closes within ____ after birth. Permanent closure occurs at ____
2 hours

3 months
Ductus arteriosus closes functionally within ____ & closes permanently in about ___
15 hours

3 weeks
Ductus venosus closes functionally when ____ & closes permanently in about ___?
when the cord is clamped


1 week
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