Reproductive System - Fertilization Flashcards
What are the three, three month periods within pregnancy called?
Trimesters, there are the first, second and third trimester.
What are the two main periods of prenatal development + length of each and what happens in each?
1.) Embryonic development (Within the first eight weeks of conception)
- Cells divide and get redistributed (rapidly)
- Baby’s organs and tissues from, as well as the structures to support and nourish the developing embryo.
2.) Fetal development ( Ninth week till birth)
- Body grows (baby and mom)
- Organs begin to function, and organ systems are now being formed.
What does human development begin with? Provide a definition.
Begins with fertilization, fertilization is the unification of an egg and a sperm cell. (Haploid from dad + Haploid from mom = Dipold —> Fertilized egg (ovum) which creates a zygote.)
Steps that occur within the female body during fertilization
1.) Within the female system, ovary will send out an egg which will get sweeped up by the fimbraie and move along into the fallopian tubes (oviduct)
2.) The eggs goal is to end up in the uterus, so muscular contractions along with the movement of cillia along the walls of the oviduct help move the egg into the ovary. (4 day process).
Why does fertilization need to occur during the early stages of the release of the egg?
If egg is not fertilized within the first 12 - 24 hours of release, the egg will lose its capacity to develop further. Therefore for the sperm and egg to join, the sperm must fertilized the egg within its early stage of release.
Explain the sperms journey
Vagina - Cervix - Uterus - Fallopian Tubes (Oviduct)
Over 150-300 million sperm are within ejaculated fluid, why do only 100 sperm make it close to the egg? (2 main reasons)
Many die off during the early stages, such as within the vagina due to its acidic environment. Males with low functionality within their prostate gland will have troubles protecting the sperm against acidic environment of the vagina, and therefore will die. Others will end up going the wrong way - into the other fallopian tube which doesn’t contain the egg.
The plasma membarane of the egg is surrounded by what two things?
1.) Zona pellucida - clear thin layer that surrounds the egg, contains carbs and proteins
2.) Corona Radiata - is a jelly-like layer that acts as extra coating for the egg.
What were the zona pellucida and corona radiatas function prior to release?
It was used for nourishment, when the egg was an ovarian follicle.
What happens when sperm make it past the vagina-cervix-uterus and is now met up with the egg in the fallopian tube.
The cap of the sperm’s head (acrosome) will release its contents (digestive enzymes - hyralucoise) to dissolve the zona pellucida and corona radiata, with the help of the motilty movement of the tail.
Once the sperm has penerated through the layers into the egg, what happens?
An Acrosomal reaction, where the plasma memberane of the egg completely depolarizes to prevent the binding of any other sperm cells.
Within the first 12 hours of peneration, what happens?
Sperms nucleus and eggs nucleus disappear. The egg is now an ovum (fertilized egg) ready to produce a zygote.
