Sperm entry and fertilization

Question 1

Step 1) Sperm entry in oocyte (b/c sperm pushes though the corona radiata &digestive enzymes disrupt the zone pellucida) This causes the oocyte to release…

Answer 1

Calcium! Which triggers:

• Release of cortical granules to harden zone pellucida
• removal of sperm receptors
• ultimately prevents polyspermy

Question 2

step 2) Fertilization occurs. What does the secondary oocyte do now

Answer 2

It completes meiosis 2 gets rid of another polar body. The nuclei of sperm and egg fuse causing the zygote, The dna replicates and it begins mitosis

Question 3

What are the 5 Stages of development (In the 1st trimester)

Answer 3

1) Cleavage 2) Implantation 3) gastrulation 4) placentation 5) Embryogenesis

Question 4

what is cleavage

Answer 4

Zygote divides w/o growth, hatches from zone pellucid and goes to implant

Question 5

What is implantation

Answer 5

contact w/ endometrium, the outer layer is the trophoblast which will fuse to the endometrium and the inside will form the fetus. Buries itself. Has yolk sac (first Blood cells, digestive, egg&sperm and umbilical cord) amniotic cavity and embryonic disk.

Question 6

What is gastrulation

Answer 6

Emrionic disc form 3 cell layers.
ectoderm: integument, nervous
Mesoderm: muscular, skeletal
Endoderm: endocrine, resp, difest, urinary, reproductive

Question 7

What is placentation

Answer 7

Chorionic villi and pool of maternal blood become the placenta.

Question 8

What does early placenta secrete

Answer 8

Human Chorionic gonadotrophic hormone to maintain compus lutem

Question 9

What does the mature placenta secrete

Answer 9

• Estrogen and progesterone
• human placental lactogen: mom use fatty acid and glucose for fetus, develop mammary glands
• human chorionic thyrotropin: increase maternal metabolism
• relaxin: to stretch flexible smooth muscle.

Question 10

What is embryogenesis

Answer 10

All major organ systems start

Question 11

2nd trimester

Answer 11

Growth and development of organ system

Question 12

3rd trimester

Answer 12

weight, mylination and organs complete

Question 13

What are teratogens

Answer 13

thing that disrupt fetal development: damage cells and effect DNA structure. Radiation, chemo, drugs, antibiotic, alcohol, and smoke. In the 1st trimester it effects ll organs but in 2nd or 3rd it’ll effect only specific organs