Development And Inheritance Flashcards
What is Fertilization?
When the sperm and oocyte combine and their nuclei fuse
What is the cell made in fertilization called?
A zygote
What does a zygote consist of?
Half the genetic information from the mother and half from the father
How many sperm cells are needed for fertilization?
Hundreds of millions
What prevents sperm cells from reaching fertilization?
Acidity of vagina canal and thick cervical mucus (millions), phagocytic leukocytes (thousands)
How many sperm survive?
Thousands
How fast do the surviving sperm travel through the tubes?
30 - 120 minutes
How long can sperm survive in the tube?
3 - 5 days
When can intercourse lead to fertilization?
a few days before ovulation
How long does an oocyte last after ovulation?
24 hours
What is capacitation?
The membrane over the sperm head thins and allows the sperm to prepare for fertilization
What are the two layers of the oocyte?
Corona Radiata and Zona Pellucida
What layer of the oocyte does the sperm penetrate through?
Corona Radiata
What must the sperm bind to in the oocyte?
A receptor in the Zona Pellucida
What is the Acrosomal Reaction?
The enzyme filled cap of the sperm releases enzymes to penetrate the 2 layers of the oocyte
What does the sperm fuse to in the oocyte?
The plasma membrane of the oocyte
How many sperm cells does it take for the acrosomal reaction?
Hundreds of sperm to release enzymes
What happens to the sperm and oocyte after fertilization?
The oocyte plasma membrane depolarizes to prevent further penetration; protiens between layers shock excess sperm to be killed and released; oocyte receptors are destroyed
What forms after fertilization?
An impenetrable protein barrier forms called the fertilization membrane
What happens to the female zygote (oocyte) upon fertilization?
Meiosis is completed and the last polar body is ejected
Once the oocyte has complete meiosis it is called a ____ until the ___ intermingle.
Ovum, DNA
How are fraternal twins created?
1% of the time, 2 oocytes are released and fertilized at the same time
How are identical twins created?
When the female zygote (oocyte) splits
What is gestation?
The time it takes for full fetal development
How long is the pre-embryonic stage?
The first 2 weeks
When does the zygote become an embryo?
From weeks 3 - 8
When does an embryo become a fetus?
From weeks 9 - birth
What happens during the embryo stage?
The organs begin to form
What is conceptus?
The zygote and associated membranes moving to the uterus
How long does conceptus take?
About 3 days
What happens in conceptus?
The zygote divides from 2 cells to 16 cells
What do the zygote cells eventually form into in the uterus?
An inner mass (embryo) and outer shell (placenta)
What are the inner cells for a few more days after reaching the uterus?
Totipotent cell
What is totipotent cell?
An ultimate stem cell capable of becoming anything (muscle, nerves, connective or epithelial tissue, organs, etc.)
What happens to the zona pullucida during embryonic development?
It is broken down for implantation in the uterus
When and where should implantation be done?
By the end of the first week and within the uterine wall.
__% - __% of blastocytes fail implantation and shed with ______
50% - 70%, menses
How does the grouping of cells implant into the uterine wall?
By digesting endometrial (stratum functionalis) cells of uterus
What happens after the grouping of cells implants into the uterine wall?
The uterus will rebuild the uterine mucosa wall and the blastocyte will be enclosed within the wall.
Why is Human Chorionic Gonadotropin (hCG) released?
It is released during implantation to keep the corpus luteum healthy, growing and secreting progesterone so menses does not begin.
When is implantation done?
By the middle of the second week
When can you see a positive pregnancy test and why?
By the middle of the second week because hCG is in the blood stream for a positive pregnancy test/
What is an ectopic pregnancy?
Implantation outside of the uterus
What is placenta previa?
When implantation happens in the inferior section of the uterus and the placenta covers the opening of the cervix
Where should implantation happen in the uterus?
In the posterior superior section of the uterus
What happens if the placenta is blocking the cervical canal?
The baby will not be able to come out during birth
What is the amnion?
A sac that surrounds the embryo and is filled with fluid of protection
What is the yolk sac?
A sac that provides nourishment until the placenta is functional; it is a source for blood cells and germ cells
What is the embryo/fetus floating in?
Amniotic Fluid
What is the allantois?
A primitive excretory duct that will become a part of the urinary bladder
What forms the outer layer of the umbilical cord?
The yolk sac and the allantois
What is the chorion?
The membrane that surrounds the amnion, yolk sac, and allantois
What is the umbilical cord?
The connections between the placenta and the fetus
When does embryogenisis happen?
During week 3
What happens in embryogenisis?
The 2 layer disc becomes 3 layers and cells go from totipotency to multipotency
What is the primitive streak?
indentation for new cells to travel along to form endoderm or mesoderm
How does the ectoderm form?
From the cells that do not migrate
The endoderm, mesoderm, and ectoderm are the _______, ______, or _______ layer of the different organ systems.
inner, middle, outer
When does the placenta start to develop?
During weeks 4 - 12 (starts in the embryonic phase and stops at the fetus phase)
What does the placenta do?
Feeds the embryo
What is the placenta composed of?
Maternal and embryonic tissue
True of False: The placenta connects to the conceptus through the umbilical cord?
True.
When is the placenta completed?
At week 14 - 16
True or False: Some substances cross the placenta due to peristalsis.
False.
Some substances cross the placenta due to SIMPLE DIFFUSION.
Which substances use simple diffusion to cross the placenta and which substances to active transport?
Simple Diffusion: Oxygen and Carbon Dioxide
Active Transport: Amino acids and Iron (they are in high demand)
Where does unoxygenated blood and waste from the fetus travel?
Through the umbilical arteries
Where does oxygen and nutrients for the fetus travel?
Through the single umbilical vein
True or False: Maternal and Fetal blood commingle.
False: Maternal and Fetal blood DO NOT commingle.
What is the placenta permeable to?
Lipid soluble fetotoxic substances
What are lipid soluble fetotoxic substances?
Alcohol, nicotine, barbiturates, antibiotics, some pathogens and more
What causes the embryo to go from a flat sheet of cells to a cylindrical?
Embryonic Folding
What is organogenesis and when does it start?
When the embryo develops organs, which starts by week 8
What are the embryo characteristics by the end of the embryonic period?
The embryo is about 3 cm long and weights 0.25 oz
How long is fetal development?
A 30 week period
What does fetal development do?
Prepare the fetus for survival outside of the womb
When does sexual differentiation begin?
During weeks 9 -12
Where is blood in the heart of the fetus shifted?
Through the foramen ovale and the ductus arteriosus
When does bone marrow begin erythrocyte production?
During weeks 9 -12
How long is the fetus at the end of week 12?
9 cm long
What happens within weeks 13 - 16
Development of sensory organs, hair, and fetal feces
What happens within weeks 16 - 20?
Limb movements are powerful and sebaceous glands coat the skin with vernix caseosa
What happens within weeks 20 -30?
Rapid weight gain, myelination (important for coordination), eyes begin to open, lungs produce surfactant, and testes descend into scrotum, fetus is 28 cm long
What happens between week 31 and birth?
Birth fat is accumulated and nails grow
What are the characteristics of the average newborn?
51 cm (20 in) and 5.5 - 8.8 lbs
How long is a full term pregnancy?
270 days or 38.5 weeks (conception to birth)
When is the due date usually set?
284 days from the last menstrual period
When does the uterus dramatically grow?
During the 2nd and 3rd trimesters
The ________ takes over the endocrine function from the ______ _______ during weeks __ - __
Placenta, corpus luteum, 12 - 17
True or False: Estrogen levels increase 30 times during childbirth.
True
What does estrogen do?
Stop ovulation, help fetal development, stimulate maternal tissue growth (uterus and mammary ducts)
What does relaxin do?
Loosen pelvis and dilate cervix
What does progesterone do?
Inhibits contractions
What does hCG do?
Stimulates male gonads to produce testosterone
What does thyrotropin do?
Increase production of thyroid hormone —> raise the metabolic rate —> increase appetite and cause hot flashes
What does prolactin do?
Stimulate growth of mammary glands
What does ACTH stimulate?
Cortisol secretion for fetal protein synthesis
How many calories should be consumed during the first trimester?
Normal Caloric intake
How much weight should be gained during the first trimester?
1 pound per month
How many calories should be consumed during the second and third trimester?
An additional 300 calories per day
How much weight should be gained during the second and third trimesters?
1 pound per week
Where is the additional weight going to during pregnancy?
Fetus (7-8), Amniotic fluid (2-3), blood (4), uterus (2-5), placenta (2-4), breast tissue (2-3), fat (3-9)
How much additional weight is added during pregnancy?
22 - 36 pounds
Why does nausea and vomiting happen during pregnancy?
Increased sensitivity to odors and decreased intestinal peristalsis
When does morning sickness usually stop?
Around week 12
What causes an increase of gastric reflux and when does it usually happen?
Upward pressure of the uterus towards the end of pregnancy
Why does constipation happen?
Decreased peristalsis (makes it harder to get everything out as waste)
Why does urination increase?
The uterus is is expanding up and down (onto the bladder) leaving less room for the bladder to expand; producing waste for yourself and fetus
Why does pulse and blood pressure increase?
Increased blood volume
What can increased uterus pressure of pelvic blood vessels cause?
Varicose veins or hemorrhoids
Why does respiration increase?
Fetal demand and lack of room for diaphragm expansion
Why do stretch marks happen?
Growth and torn connective tissue
What causes contractions?
Progesterone drops and estrogen increases
What is the blood show?
A plug of mucus covering the cervix is expelled with a small amount of blood about 2 days before labor
Why is oxytocin produced during labor?
To intensify contractions
What is the cervical dilation stage?
10 cm diameter dilation; takes 6 - 12 hours
What are the characteristics of contractions when they start?
happen every 3 - 30 minutes and last for 20 - 40 seconds
What are the characteristics of contractions when they end?
happen every 1.5 - 2 minutes and last for 1 minute
What happens at the end of the dilation stage?
The amniotic membrane will rupture
What happens in the expulsion stage?
The fetal head will enter the cervical canal
How long does the expulsion stage last?
Either minutes or hours
Where should the fetal head be facing during the expulsion stage?
Down and facing the maternal spine
What may tear during birth?
The posterior vaginal wall and perineum
What will the baby aspirate during it’s first breath?
Mucus from the mouth and nose
How is the baby separated from the umbilical cord?
The cord is double clamped and cut in the middle
What is after birth?
Delivering the placenta and membranes
What is a breech presentation?
The buttocks and legs are down and coming out first
What is a caesarian section?
A surgical birth where the doctor cuts into the abdominal cavity and extracts the baby
What is involution?
The uterus reducing to pre - pregnancy size
How does the infants blood flow increase?
By the fetus breathing and expanding the lungs
Circulation in the heart adjusts as the _______ _____ and ______ __________ closes
foramen ovale and ductus arteriosus
What helps the fetus regulate their temperature?
The automatic breakdown of brown fat
True or False? The infant produces heat fast and loses it slowly.
False: The infant produces heat SLOW and loses it QUICKLY.
Is the fetal intestine of the infant sterile (free of bacteria)?
Yes
Where does the infant receive bacterial flora?
Breast milk or formula
Why is dehydration a big risk in infants?
Infant urine is very dilute because their kidneys aren’t very efficient
How is breast milk secretion and production increased?
The infant sucking at the nipple
What is breast milk good for?
Passive immunity for fetus, encourages involution, increases metabolic rate to consume the fat stored during pregnancy
What hormone establishes and maintains breast milk supply?
Prolactin
When does prolactin spike?
1 hour during each feed to prepare for the next feeding
True or False: Prolactin will stay high as long as breast feeding is constant.
False: Prolactin will decrease over time, even with constant breastfeeding
How much breast milk can be produced per day?
About 1.5 L a day
How long can breast milk production last?
For years if breastfeeding never stops
What is secreted from the breasts during the first 72 hours after birth?
Colostrum
When does the breast start producing only breast milk (no colostrum)?
After a week
What is the main difference between colostrum and breastmilk?
Colostrum has a lot more immunoglobulins and breast milk has more fat
When do most mothers switch children over to cow’s milk?
Around 6 months
How does cows milk compare to breast milk?
Cow’s milk has less fat and more proteins, sodium, phosphorus, and calcium
What is a genotype?
The genetic makeup
What is a phenotype?
How the genes are outwardly expressed (appearance)
What are sex chromosomes?
The pair that determines male or female (XY or XX); 23rd chromosome
How many chromosomes do we get from each parent?
1
What is an allele?
A copy of 1 gene
How many alleles do we get from each parent?
1
What makes someone homozygous?
2 identical alleles for a single gene (two blue eye parents)
What makes someone heterozygous?
2 different alleles for a single gene (one parent with blue eyes and one parent with brown eyes)
Which allele will show in heterozygous?
The dominant allele
Which allele will not show in heterozygous?
The recessive allele
What is co-dominance?
When two genes are dominant and they both show
What is a carrier?
Someone with a recessive gene that can be passed on
What is a mutation?
A change in DNA sequence that may or may not affect the phenotype
What is Down’s Syndrome?
3 copies of chromosome 21 (only supposed to have 2)
What is Turner Syndrome?
Only 1 copy of X chromosome
Who and what does Turner Syndrome affect?
Women; sexual organs do not mature
What is Trisomy 16?
3 copies of chromosome 16; It is the common cause of miscarriage
