Pregnancy & Development - Exam 4 Flashcards
Where does fertilization occur?
near ovary
Where does implantation occur?
in uterus
Gestation period
time from last mentrual period until birth (~280 days)
Embryo
fertilization through week 8
Fetus
week 9 through birth
How long is an oocyte viable?
12-24 hours
How long is sperm viable?
24-48 hours after ejaculation
For fertilization to occur, coitus must happen when?
two days before ovulation
24 hours after ovulation
In order for fertilization to occur, what must take place?
sperm must breach oocyte coverings
What is the acrosomal reaction?
acrosome (protective cap over head of sperm) has enzymes to allow for entry into oocyte
When does the oocyte do to protect against another sperm entering?
oocyte swells
What triggers the completion of meiosis II?
fertilization
From zygote to gastrula, explain the process of a fertilized egg
- Zygote - fertilized egg
- Cleavage - cell division with a decrease in size
- 4-Cell stage
- Cleavage
- Morula - ball of cells
- Blastocyst/Blastula - hollow ball of cells
- Implantation
- Gastrula - gastrulation
What is used for stem cell research?
blastocyst/blastula
Gastrulation
formation of 3 layers
allows for cell differentiation
When is implantation completed?
12th day after ovulation
What prevents menstruation?
-elevation of estrogen and progesterone
What keeps estrogen and progesterone elevated to prevent menstruation?
hCG
human chorionic gonadotropin
What takes the place of corpus luteum in hormone production?
placenta formation
What is the maternal aspect of the placenta?
blood pockets
What creates 3 germ layers in the embryo?
granulation
What are the 3 germ layers?
ectoderm
mesoderm
endoderm
Other than estrogen and progesterone, what else does the placenta secrete?
human placental lactogen (hPL)
relaxin
What does human placental lactogen do?
maturation of breasts
fetal growth
glucose sparing in mother (for fetus)
What does relaxin do?
relaxed pelvic ligaments and pubic symphysis
Chorionic villi
fetal portion of placenta, where exchange between mom and baby occurs
Amnion
sac filled with amniotic fluid
What are the functions of the amnion?
protection
buffer of temperature
buoyancy
What is the purpose of fetal vascular shunts?
bypass lungs and liver because they are not fully developed in the womb
What is the vascular shunt that bypasses the lungs?
foramen ovale
What is the vascular shunt that passes blood through the liver and into the vena cava of the heart?
ductus venosus
What is the vascular shunt that moves blood from the pulmonary artery to the aorta?
ductus arteriosus
What stimulates the closure of the vascular shunts?
At birth, the increase in blood pressure and decrease in pulmonary pressure closes the ductus arteriosus. This builds pressure in the left atrium and reduces right atrial pressure, stimulating the closure of the foramen ovale
What are the physiological changes during pregnancy?
- increase in metabolic demand
- cardiovascular system change
- increase in TV of respiratory system
- increased urine production
What is the most significant and important physiological change that occurs during pregnancy?
- cardiovascular system change
- cardiac output must increase
- BP must increase
- BV must increase
What determines the time labor starts?
fetus
During the last few weeks of pregnancy, the fetus secretes what which stimulates what?
fetus secretes cortisol which stimulates placenta to secrete more estrogen
What causes the placenta to produce prostaglandins?
fetal oxytocin
Oxytocin and prostaglandins function as what?
powerful uterine muscle stimulants
What is the positive feedback loop that causes labor to progress until birth?
- posterior pituitary produces oxytocin
- oxytocin stimulates contraction
- prostaglandins produced
- prostaglandins stimulates production of more oxytocin
Overall, what causes the reflex to breathe?
build up of hydrogen ions
Explain the process of a baby’s first breath?
increase in CO2
causes central acidosis
stimulates respiratory control centers to trigger first inspiration
What needs to be secreted by the infant’s type II cells to help lung inflation?
surfactant
What happens to the ductus arteriosus and venosus after birth?
become ligaments
What hormone stimulates milk production?
prolactin
What hormone stimulates milk release?
oxytocin
What can be collected from adults for DNA analysis?
white blood cells
skin cells
cells from biopsies
What can be collected from a fetus for DNA analysis?
cells in amniotic fluid (amniocentesis)
cells from placenta (chorionic villus sampling)
The collection of DNA for analysis in a fetus could stimulate what?
spontaneous abortion
What causes an altered number of chromosomes?
nondisjunction
What is nondisjunction?
failure of chromosomes to separate during meiosis I or II
What is Trisomy 21?
3 chromosomes on 21
Down’s Syndrome
The risk factor for Down’s syndrome increases with what?
maternal age
What is the risk factor for Down’s syndrome in mothers ages 25, 30, 35, 40, and 45?
25- 1 in 1300 30 - 1 in 1000 35 - 1 in 400 40 - 1 in 100 45 - 1 in 35
What is Turner Syndrome?
XO
no SRY gene present to make a male
An XXX or XYY syndrome could result in what?
taller girls
elevated phenotypes
What is the rate of miscarriages?
50% of pregnancies
How common are chromosomal abnormalities?
present in 1 in 200 births
Chromosomal abnormalities are responsible for how many early deaths?
5-7%
What is a karyotype?
a number and visual appearance of chromosomes in an organism or species
Why does the risk of chromosomal abnormalities increase with the age of the mother?
The eggs are not as fresh or viable
