UNIT 28 (final exam)
Sex chromosomes
-the pair that determines male or female (XY or XX) -Everyone inherits 1 chromosome in each pair from each parent
Conceptus
-the zygote and associated membranes moving to the uterus -A 16 cell _____ should reach the uterus in 3 days
Embryo
-weeks 3-8 -inner mass floating in the uterus
Heterozygous
2 different alleles for a single gene
Homozygous
2 identical alleles for a single gene
Yolk sac and allantois
these form the outer layer of umbilical cord
Zona pellucida
this is broken down for implantation
Gestation
time for full fetal development
Amnion
-surrounds the embryo -filled with fluid for protection
Relaxin
secreted to loosen pelvis and dilate cervix
Placenta
-the outer shell of the embryo -takes over the endocrine function from the corpus luteum during weeks 12 - 17
Plasma membrane
-1 sperm will get through both layers and fuse to the ____ ____ -After fertilization the ____ ____ depolarizes to prevent more penetration and proteins between layers cause sperm to be released and receptors to be destroyed
Cervical dilation stage
-10 cm in diameter -takes 6-12 hours
Fertilization
-A sperm and oocyte combine and their nuclei fuse -The new cell is a zygote, half genetic material from mother and father -Hundreds of millions of sperm are released during ejaculation -Millions of sperm and killed due to acidity almost immediately -Millions more sperm are blocked by thick cervical mucus -Thousands more are killed by phagocytic leukocytes -The thousands of remaining sperm travel to the tubes in 30 - 120 minutes -Sperm can survive for 3-5 days in the tubes if they don't find a oocyte -Intercourse a few days before ovulation can still lead to fertilization -Oocyte only last for about 24 hours following ovulation
Fetal development
-At end of week 12 fetus is 9 cm long -Weeks 21 - 30 is rapid weight gain, begin myelination, eyes begin to open, lungs produce surfactant, and testes descend into scrotum. 28 cm long -Weeks 31 till birth fat is accumulated, nails grow -At birth average newborn is 51 cm (20 in) and 5.5 - 8.8 lbs.
Implantation
-At the end of the first week, in the uterine wall -50%-75% of blastocysts fail _______, shed with menses -Must digest endometrial cells to implant in uterine wall -Uterine mucosa rebuilds and envelops the blastocyst -done by the middle of the second week and enough hCG is in the blood stream for a positive pregnancy test
Placenta development
-Develops during weeks 4 - 12, feeds the embryo -Maternal and embryonic tissue combined -Connects to the conceptus through the umbilical cord -is complete at week 14 - 16 -Some substances cross placenta due to simple diffusion (O2, CO2, etc.) -Amino acids and iron need active transport and they are in high demand -Unoxygenated blood and waste travel from the fetus through umbilical arteries -O2 and nutrients travel through the single umbilical vein -Maternal and fetal blood do not commingle -Placenta is permeable to lipid soluble fetotoxic substances: alcohol, nicotine, barbiturates, antibiotics, some pathogens, and more -The embryo goes from a flat sheet of cells to cylindrical due to embryonic folding
Embryogenesis
-During week 3 the 2 layered disc becomes a 3 layered disc -Cells go from totipotency to multipotency
Adjustment of the infant at birth and postnatal stages
-Infant starts breathing as lungs expand which also increases blood flow -Circulation in the heart adjusts as foramen ovale and ductus arteriosus closes -Infants must regulate body temperature, they produce heat slow and lose it quickly, they breakdown brown fat automatically -Fetal intestine is sterile and bacterial flora must be ingested in breast milk or formula -Urine is very dilute making dehydration a bigger risk
Lactation
-Milk is secreted and produced in response to infant sucking at nipple -Good for passive immunity, encourages involution, and increases metabolic rate to consume fat stored during pregnancy -Prolactin establishes and maintains supply of breast milk. It spikes for 1 hour during each feeding to prepare for next feeding -Even with constant breastfeeding, prolactin will decrease over time. It can last for years if never stopped, produce about 1.5 L per day -First 72 hours after birth it is colostrum secreted. Small amounts, lots of immunoglobulins. Mixture of colostrum and milk for about 7 days
Changes in organ systems
-Nausea and vomiting due to increased sensitivity to odors and decreased intestinal peristalsis. Usually stops by week 12 -Increased gastric reflux near end due to upward pressure of uterus -Constipation due to decreased peristalsis -Increase in urination due to downward pressure of uterus and increased urine production -Pulse and BP rise due to increased blood volume -Uterus pressure of pelvic blood vessels cause varicose veins or hemorrhoids -Respiration rate increases due to fetal demand and lack of room for diaphragm expansion -Stretch marks from growth and torn connective tissue
Physiology of labor
-Progesterone drops and estrogen continues to rise to begin contractions -About 2 days before labor a plug of mucus covering the cervix is expelled along with a small amount of blood ("bloody show") -Oxytocin production increases to intensify contractions
Zygote
-Upon fertilization meiosis is completed, polar body ejected -The oocyte is now an ovum until the DNA can intermingle -1% of the time 2 oocytes are released and fertilized, fraternal twins -Less common, the _____ splits and identical twins are formed
Breech presentation
-buttocks and legs are down -Caesarian section
Afterbirth
-delivering placenta and membranes -starts post partum period which lasts 6 weeks to return to a non pregnant state
Organogenesis
-embryo develops organs -all started by week 8
Expulsion stage
-fetal head enters the canal, can last minutes or hours. -Head should be down and facing maternal spine. -Posterior vaginal wall and perineum may tear (episiotomy not as common) -Aspirate mucus from mouth and nose before first breath, double clamp cord and cut in between
Estrogen
-levels increase 30 times by childbirth -stops ovulation, helps fetal development, and stimulates maternal tissue growth (uterus and mammary ducts)
Yolk sac
-provides nourishment until placenta is functional -source of blood cells and germ cells
Human chronic gonadotropin (hCG)
-released to keep the corpus luteum healthy, growing, and secreting progesterone -stimulates male gonads to produce testosterone
Capacitation
-sperm prepared for fertilization -membrane over the head thins
Contractions
-start at every 3-30 minutes and last 20-40 seconds -they end as a _____ every 1.5 - 2 minutes and last 1 minute
Full term
270 days or 38.5 weeks from conception to birth
Corona radiata/ zona pellucida
Sperm must penetrate ____ ____ and then bind to a receptor in the _____ _____
2nd and 3rd trimesters
Uterus grows dramatically during ____ and ____ _______
Allele
a copy of 1 gene
Codominance
a mixing of the alleles will show
Fertilization membrane
an impenetrable barrier then forms called this
2 layers of the oocyte
corona radiata and zona pellucida
Layers
during the second week cells organize into these
Acrosomal reaction
enzyme filled cap releases its enzymes to penetrate the 2 layers
Pre-embryonic stage
first 2 weeks
Totipotent
for a few more days the inner cells are ______
Genotype
genetic makeup
Phenotype
how the genes are outwardly expressed
Placenta previa
implantation in inferior uterus and placenta covers the opening of the cervix
Ectopic pregnancy
implantation outside of uterus
Thyrotropin
increases production of thyroid hormone to raise metabolic rate which increases appetite and causes hot flashes
Progesterone
inhibits contractions
Allantois
primitive excretory duct that will become part of urinary bladder
Amniotic membrane
rupture by the end of the dilation stage
Due date
set 284 day from last menstrual period
Prolactin
stimulates growth of mammary glands
Dominant
the allele that will show in heterozygous
Recessive
the allele that won't show in heterozygous
Chorion
the membrane that surrounds all others
Involution
uterus reducing to pre pregnancy size
Fetus
weeks 9 to birth