Lecture 27 Flashcards
(12 cards)
How are identical twins formed?
1 fertilized egg (ovum) splits and develops into 2 babies with the same genetic information
How are fraternal twins formed?
2 eggs (ova) are fertilized by 2 sperm and produce 2 genetically unique children.
How are triplets formed?
They are usually a pair of identical twins and one fraternal triplet. 2 eggs are fertilized by 2 sperm and 1 of them split.
How are the embryos contained for dizygotic twinning? How does it differ from monozygotic twinning.
Dizygotic: dichorionic and diamniotic (2 placenta, 2 amniotic fluids)
Monozygotic (3 options):
1) Same as dizygotic because the egg splits.
2) Monochorionic and diamniotic (1 placenta, 2 amniotic sacs), egg split at hatching
3) Monochorionic and monoamniotic (1 placenta, 1 amniotic sac), blastocyst splitting after implantation
What makes it more likely to have twins/triplets?
IVF, age, genetics, clinically obese, race
What is IVF? What is it a treatment option for? Why?
In vitro fertilization
treatment plan for infertility:
- fallopian tube damage
- ovulation issues
- endometriosis or fibroids
- sperm issues
-unexplained infertility
- preserve fertility due to cancer or other health problems
How does IVF work?
1) screen to see if eggs, sperm, uterus are good for IVF
2) stimulates ovaries for FSH and LH
3) hCG is used to help eggs mature and develop
4) Take progesterone to thicken lining for uterus and increase chances of implantation success
5) Eggs are retrieved from follicles and sperm retrieval follows shortly after
What are the 3 options for fertilization?
1) mix eggs and sperm together
2) intracytoplasmic sperm injection (directly put it in the egg)
3) Embryo transfer places one or more embryo in uterus and hope they attach
What is the main sugar in milk and what is this sugar made up of? Explain how this milk sugar is made in the breast epithelial cells.
Lactose = glucose + galactose
1) Glucose is taken up from the blood by GLUT1 into the breast epithelial cells
2) Glucose is transported into the golgi or phosphorylated by hexokinase to become Glucose 6-phosphate. G6P is acted on by phosphoglucomutase to become G1P and is then converted to UDP-galactose in the cytoplasm
3) UDP-galactose is transported into the golgi to be combined with glucose.
4) The 1:1 complex of lactalbumin and Beta4-glycosyl transferase forms the beta1-4 bond between glucose and galactose to form lactose.
5) Lactose is then concentrated in the milk, where it is then sent out in order to feed the baby.
What are the four hormones that act on the breast tissue and why?
1) Progesterone and estrogen: stimulates growth and development of the mammary glands
2) prolactin: stimulates milk production
3) Oxytocin: stimulates milk secretion (milk letdown)
After delivery of the baby, what are the hormonal and neural controls of lactation, such that women are able to produce and secrete milk for their baby? What occurs hormonally as a result of sustained levels of prolactin?
1) After delivery, prolactin levels and milk synthesis are going to increase. Since dopamine levels are maintained very low while breastfeeding, this allows prolactin levels to be high for the milk synthesis.
2) Suckling at the nipple allows for the positive feedback loop for oxytocin secretion, thus stimulating more milk ejection. Only when the baby stops suckling does the positive feedback loop for oxytocin cease.
3) Over time, the secretion of milk will become a reflex. External signals will end up triggering milk ejection. This is your body’s way of getting ready and anticipating to feed your baby.
4) There are specific signals in the brain that are going to affect the hypothalamus, such that levels of GnRH become suppressed, such that levels of FSH and LH drop as well. As a result of these specific signals, this will prevent ovulation from being able to occur.
After delivery of the baby, does the mothers body begin to produce milk immediately?
Nope! The breast begin to produce something called colostrum (~30 mL) for the first day which is a yellow liquid very high in protein, antibodies, and nutrients.
Transitional milk: day 3-14; ~500 mL/day is produced, containing essential enzymes and hormones.
Breast milk: day 14 and on; 550-1150 mL/day and meets all the babies needs for the first 6 months (except Vit D)
