Reproduction: fertilization and childbirth Flashcards
Where does fertilization typically occur in the female reproductive tract?
A. Cervix
B. Uterus
C. Ampulla of the fallopian tube
D. Infundibulum of the fallopian tube
Fertilization typically occurs in the ampulla, the widened region of the fallopian tube. While sperm may enter through the cervix and uterus, the actual union of sperm and egg occurs in the ampulla.
Which of the following
sequences accurately describes the key events of fertilization?
A. Capacitation → Acrosome reaction → Sperm-egg fusion → Cortical reaction
B. Acrosome reaction → Capacitation → Zona hardening → Sperm fusion
C. Sperm fusion → Cortical granule release → Capacitation → Meiosis II
D. Capacitation → Zona hardening → Sperm entry → Acrosome reaction
Capacitation – sperm undergo physiological changes for fertilization.
Acrosome reaction – enzymes are released to penetrate the zona pellucida.
Sperm-egg fusion – plasma membranes fuse.
Cortical reaction – prevents polyspermy.
Why is polyspermy not favoured and how is polyspermy prevented?
Not favoured because more than one sperm wont make the zygote viable since it results in an abnormla number of chromosomes
Polyspermy is prevented by the oocyte, whihc creates a block to prevent the entry of sperm
Which of the follow is true on how the oocyte blocks polyspermy
A. oocyte removes zona pellucia
B. Change of membrane potential
C. Hardening of the zona pellucida with enzymes
D. Has enzymes that inactivate the sperm binding receptor
E. release contents from cortical grandule
The oocyte does not remove the zona pellucida
Polyspermy is prevented by which of the following mechanisms?
A. Inhibition of sperm motility by acidic pH
B. Release of cortical granules that harden zona pellucida
C. Increased production of progesterone
D. Sperm binding to trophoblast receptors
After the first sperm fuses with the egg, cortical granules release enzymes that harden the zona pellucida, forming a block to further sperm entry and thus preventing polyspermy.
What happens to the fertilized egg within the first 5 days post-fertilization?
A. It implants directly into the uterine wall
B. It transforms into a morula and travels toward the uterus
C. It develops into a blastocyst and completes implantation
D. It fuses with another ovum to become a zygote
It transforms into a morula and travels toward the uterus
The fertilized zygote undergoes cleavage to become a morula, which travels toward the uterus. Around day 5, it becomes a blastocyst, and implantation occurs around day 6–7, not during the first 5 days.
List the correct sequene of how a baby’s name is changed during pregnancy
- fetus, zygote, embryo, morula
- zygote (when DNA is replicated)
- morula
- embryo (first two months)
- fetus (after two months)
Which of the following best defines implantation and its key process?
A. Formation of morula and migration into cervix
B. Attachment of inner cell mass to the myometrium
C. Invasion of trophoblast cells into endometrium around day 6-7
D. Hatching of blastocyst and expansion of zona pellucida
Implantation begins around day 6–7 when trophoblast cells of the blastocyst invade the endometrium. The inner cell mass will eventually become the embryo, but it’s the trophoblast that initiates implantation.
Which combination correctly lists both the functions and major hormones of the placenta?
A. Gas exchange, anti-insulin hormone: estrogen and LH
B. Nutrient filtration, GH-like hormone: hPL and progesterone
C. Immunological barrier, maintains corpus luteum: hCG and hPL
D. Oxygen supply, sperm attraction: estrogen and oxytocin
The placenta acts as an immunological barrier and secretes hCG to maintain the corpus luteum early in pregnancy. It also produces hPL (human placental lactogen) for metabolic adaptation.
Which process gives identical twins and fraternal twins?
- division of totoipotent morula cells
- fertilization of two oocytes
Division of totopoitant cells give identical twins
Fertilization of two oocytes gives fraternal twins (non-identical)
Which is true about a blastocyts:
A. It is implanted on the uterine wall
B. It is immediately placed in the uterine lining
C. The outer layer has a trophoblast which becomes the placenta
D. It loses its zona pellucida
E. it looses it totipotency
F. A and D
The correct answer is :
- it looses its zona pellucida
- the outer layer has a trophoblast which becomes the placenta
- it is implanted on the uterine wall 4-5 days after fertilization (KNOW)
- it looses it totipotency
Why the others are incorrect:
B- it takes 4-5 days to be on the uterine wall
E. C is also correct
What does does it mean when a blastocysts looses its totipotency?
It means that each cell in the blastocyst have an assigned role now (yay)
Which of the following best describes the process of implantation?
A. The morula attaches to the uterine wall and invades the myometrium B. The blastocyst adheres to the endometrium, and trophoblast cells invade to form the placenta
C. The zygote fuses with endometrial blood vessels to initiate placental development
D. The inner cell mass of the blastocyst penetrates the cervical canal for nutrient absorption
The blastocysts adheres to the endometrium and trphoblast cells invade the placenta and throphoblasts ared fused on the uterine lining
Why is there a physical barrier in between the maternal sinus and the maternal blood (venule and arteriole)?
There is a physical barrier to prevent the mother and the babies blood from mixing (recall the effects of different blood types interacting with eachother)
Exchange still occurs but there is no mixing
Why do we need a spike of human gonadotrophin hormone during the early stages of pregnancy?
- we need HCG to maintain the corpus luteum
Why do we need the corpus luteum?
- to prevent dessication of the corpus luteum
- the cL gives a lot of progesterone and estrogen to maintain the placenta during the early stages of pregnancy
- through pregnancy the corpus luteum desentegrates
What is the role of human chorionic somatomamotropin (hCS) and human placental lactogen (hPL) (protein)?
A. Maintaining the corupus luteum
B. Growth of the uterus (myometrium) and mammary ducts
C. Decreases urine contractions, growth of mammary alveolar glands, and secretion of unfriendly sperm mucus in the cervix
D. Has GH and anti-insulin like actions and helps the fetus get more glucose
Has GH and anti-insulin like actions and helps the fetus get more glucose
A- is for hcg
B- estrogen
C- progesterone
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Why are LH and FSH inhibited during pregnancy when the placenta is active?
A. To stimulate ovulation in the second trimester
B. To support follicle maturation for twin development
C. Because high levels of estrogen and progesterone from the placenta suppress the hypothalamic-pituitary axis
D. Because hCG directly stimulates LH and FSH production from the placenta
The placenta produces estrogen and progesterone, which exert negative feedback on the hypothalamus and anterior pituitary, thereby suppressing LH and FSH. This prevents ovulation and new follicle development during pregnancy.
How do porgesterone and estrogen differ in developing the mammary glands?
Progesterone helps growth of mammary alveolar glands
Estrogen helps with growth in mammary ducts
Why is the placenta considered an endocrine gland, and how does it obtain androgens?
A. The placenta produces digestive enzymes and absorbs maternal testosterone for conversion to estrogen
B. The placenta synthesizes hormones like hCG and estrogen, and relies on fetal adrenal conversion of progesterone to androgens
C. The placenta stores maternal LH and converts it into progesterone using syncytiotrophoblasts
D. The placenta secretes oxytocin, and fetal liver converts cholesterol into androgens for estrogen synthesis
The placenta synthesizes hormones like hCG and estrogen, and relies on fetal adrenal conversion of progesterone to androgens
How does the placenta obtain androgens? (starting with obtaining cholesterol from the mother)
Know that the placenta does not directly make androgens.
How it gets androgens:
Progesterone goes into the fetus and the fetus converts progesterone to androgens
The fetus has the enzymes capable of converting progesterone into androgens
