Stages Of Pregnancy

Question 1

What occurs in the first week of pregnancy?

Answer 1

1. Ovulation
2. Fertilization and Zygote formation
3. Mechanisms against polyspermy (fast and slow block against polyspermy)
4. Cleavage
5. Implantation and Human Chorionic Gonadotropin (HCG) secretion by embryo

Question 2

What occurs in the second stage in the first week of pregnancy?

Answer 2

-embryo is fertilized by 1 sperm

Question 3

What is polyspermy?

Answer 3

Is more than 1 sperm fertilizing an egg resulting in a miscarriage

Question 4

What are the names of the two mechanisms against polyspermy?

Answer 4

• fast block

- slow block

Question 5

What uses these method against polyspermy? What occurs in the 2 methods?

Answer 5

-deployed by the egg to protect against polyspermy
Fast block:
-10 sec after fertilization
-uses Na+ to create an electric barrier to shock sperm
Slow block:
-1 min after fertilization
-forms physical barriers of water that blocks sperm

Question 6

What is Cleavage?

Answer 6

Cell division that occurs with Day 1 to Day 5

Question 7

What is the role of HUman Chrionic Gouadotropin?

Answer 7

-pregnancy hormones

Question 8

Why is cell division important for the baby?

Answer 8

The multiple cells form different parts of the developing baby’s body

Question 9

What occurs on 1st week on phase 4?

Answer 9

• cleavage

- cell division

Question 10

What is Human Chorionic Gonadotropin?

Answer 10

-pregnancy hormone

Question 11

What is the last stage of pregnancy in the first week?

Answer 11

-Implantation and human chorionic gonadotropin (hCG) secretion by embryp

Question 12

What events occurs on the final stage of pregnancy in the fist week?

Answer 12

1. implantation of embryo into uterus
2. emberyo secretes HCG in blood stream
3. HCG maintains corpus Luteum
4. Corpus Luteum secretes progesterone to maintain endomentrium is not shed

Question 13

What events are going to occur in week 2 & 3 of pregnancy?

Answer 13

6. Primative streak formation
7. Development of embryonic and extra embryonic structures ( Placenta, chorion, amnion, and umbilical cord)
8. Gastrulation

Question 14

What is the Primitive Steak formation?

Answer 14

• formation of the central axis

- forms all organs symmetrical

Question 15

What is a term used to describe symmetrical organs?

Answer 15

-bilatera symmetry

Question 16

What occurs in phase 7 in week 2&3?

Answer 16

• forms structures outside the embryos

- extra embryonic structures

Question 17

What structures are formed in phase 7 on week 3&4?

Answer 17

• Umbilical cord
• placenta
• amnion
• fluid

Question 18

What occurs on Week 2 & 3 in stage 8?

Answer 18

• gastrulation

- foundation for organs to form

Question 19

What is the foundation formed in stage 8 in week 3&4?

Answer 19

Ectoderm:
-skin
-nervous system
Mesoderm:
-all types of muscle, bone, cartilage
Endoderm:
-digestive system

Question 20

What events occur on Week 4 of Pregnancy?

Answer 20

9. Organogenesis
10. Heart starts beating
11. Limb buds appear

Question 21

What events occur in Week 5 & 6 of Pregnancy?

Answer 21

12. Sex determining region on the Y chromosome (SRY) gene activation
13. Ossification of skeleton begins

Question 22

What happens in Week 5 & 6 in phase 12?

Answer 22

• gender development

- SRY gene begins to select male or female

Question 23

What is ossification?

Answer 23

-tissue is converting to bone tissue

Question 24

What will occur in Week 5 & 6 in the phase 13?

Answer 24

-bone tissue forming

Question 25

What events occur in Week 7 & 8?

Answer 25

14. Apoptosis

15. Neuron generate action potentials (electrical signals)

Question 26

What occurs in Week 7 in the stage 14?

Answer 26

• apoptosis: programmed cell death

- will occur with skin in between toes and finger.

Question 27

What occurs in week 7 in the stage 14?

Answer 27

• apoptosis: programmed cell death

- will occur with skin in between toes and finger.

Question 28

What occur in Week 4 in stage 15?

Answer 28

-neurons for cell to cell signals