Conception and Development

Question 1

What is gametogenesis?

Answer 1

The creation of reproductive cells in both male (at puberty) and female (in utero)

Question 1

What is oogenesis?

Answer 1

Formation of ova or female gametes

Question 2

What is spermatogenesis?

Answer 2

Formation of sperm or male gametes

Question 3

What are gametes?

Answer 3

Ova and sperm

Question 4

What is meant by diploid?

Answer 4

46 chromosomes

Question 5

What is meant by haploid?

Answer 5

23 chromosomes

Question 6

What is meiosis?

Answer 6

In meiosis-each contributing cell contains 23 chromosomes from each parent. Differs from mitosis because mitosis has 46 chromosomes.

Question 7

Which parent determines the sex of the baby?

Answer 7

The father. His sperm will either have XX (female) or XY (male) sex chromosome. Mother will always contribute XX sex chromosome.

Question 8

What are teratogens?

Answer 8

Environmental substances damaging to fetus. Most damaging to fetus is contacted in embryonic period (from 2-8 weeks) while all major organs are developing

Question 9

What is a zygote?

Answer 9

A fertilized ovum until it keeps dividing to reach 12-16 cells. This division doesn’t make the zygote bigger than the original ova. Each division made the cell smaller and smaller, they just become smaller but multiply.

Question 10

What is a morula?

Answer 10

After it passes the zygote stage (12-16 cells), it becomes a morula. The morula is contained in a sac of fluid called a blastocyst. The inner morula becomes the fetus and the outer blastocyst becomes the placenta and membranes. The outer blastocyst is called the trophoblast and the inner morula is called the inner cell mass.

Question 11

What is the decidua?

Answer 11

The well nourished endometrium in the secretory phase of the woman’s cycle. It is ready for implantation.

Question 12

What is implantation also called and when does it happen?

Answer 12

Nidation and it happens around 6-10 days after the zygote is first formed.

Question 13

Why is the placement of implantation important?

Answer 13

Best place is the fundus. This will be where the placenta attaches. This is best spot for three reasons:
1. Best blood flow to nourish
2. Thickness of location is best for the placenta
3. Muscles in fundus are strong to compress spot where placenta detaches and stop blood flow after birth

Question 14

When is the pre-embryonic period? What happens during it?

Answer 14

First two weeks. From fertilization to implantation.

Question 15

What is the embryonic period? What happens during it?

Answer 15

Start of 3rd week through end of 8th week. All major body organs are completely formed, just in miniature.

Question 16

What are the three germ layers that all body systems derive from?

Answer 16

Endo
Meso
Ectoderm

Question 17

What is formed from the endoderm?

Answer 17

Lining of GI, respiratory, bladder
Liver and pancreas

Question 18

What is formed from the mesoderm?

Answer 18

Bone, muscle, blood, lymph and all connective tissues
Spleen
Kidneys
Repro organs
Heart

Question 19

What is formed from ectoderm?

Answer 19

Brain and nervous system
Skin
Hair and nails

Question 20

What is considered the fetal period?

Answer 20

Beginning at 9 weeks through birth

Question 21

Major developments at 4 weeks gestation.

Answer 21

Neural tube closes
Face and upper respiratory tract begin to form
Upper limb buds

Question 22

Major developments at 6 weeks gestation.

Answer 22

Heart reaches final four chamber form.
Face midline
External ear begins

Question 23

Major developments at 12 week gestation.

Answer 23

Sex can be determined.

Question 24

Major developments at 16 weeks gestation.

Answer 24

Length grows rapidly. Quickening may be felt.

Question 25

Major developments at 20 weeks gestation.

Answer 25

Vernix Lanugo Brown fat Eyebrows and hair

Question 26

Major developments at 24 weeks.

Answer 26

Skin is translucent. Surfactant begins to develop.

Question 27

Major developments at 28 weeks.

Answer 27

Lungs and CNS mature Gains fat Eyes reopen Flips to head down

Question 28

Major developments at 36 weeks.

Answer 28

Weight gain Breasts plump Testes in scrotum

Question 29

What is two types of tissue in blastocyst?

Answer 29

The outer trophoblast which becomes the placenta. The inner cell mass which becomes the fetus.

Question 30

What is the chorionic villus?

Answer 30

The part of the placenta where exchange of nutrients and oxygen and carbon dioxide takes place. The chorionic villi are the projections (like little roots that anchor into the uterine wall).

Question 31

When does transfer of mom's antibodies (IgG) take place in development?

Answer 31

Last trimester. If baby is born premature, won't have the passive immunity that a full term baby will have.

Question 32

What secretes the hCG in early pregnancy?

Answer 32

The conceptus. This hormone signals progesterone levels to stay elevated to accommodate implantation.

Question 33

What role does the placenta play as an endocrine organ?

Answer 33

Eventually takes over the role in producing progesterone, estrogen. Also produces human chorionic somatomammotropin (for breast development) and relaxin in last trimester.

Question 34

What is the amnion and chorion?

Answer 34

The amnion is the inner membrane and the chorion is the outer membrane. Together they are referred to the bag of waters. The chorion (outer layer is continuous with the implanted part of the placenta.

Question 35

What is the fetal and maternal sides of the placenta called?

Answer 35

Fetal-Chorion Maternal-decidua basalis

Question 36

What are the contents of the umbilical cord?

Answer 36

2 Arteries-carries deoxygenated blood from fetus 1 Vein-carries oxygenated blood to fetus Wharton's Jelly-shock absorber that cushions the cord

Question 37

What is the ductus venosus?

Answer 37

A shunt in fetus that bypasses the liver. (baby's liver not needed yet because mom's liver is doing the job)

Question 38

What is the foramen ovale?

Answer 38

Shunt from right atrium to left atrium that bypasses the non-functioning lungs. Closes and fibrin tissue covers it within 3 months after birth.

Question 39

What is the ductus arteriosus?

Answer 39

Shunt from pulmonary artery to aorta. Allows for bypass of pulmonary circulation in utero.

Question 40

What are monozygotic twins?

Answer 40

Identical. Came from same egg and sperm and later on (usually in blastocyst stage) develops into two morulas. Usually share placenta and amnion.

Question 41

What are dizygotic twins?

Answer 41

Fraternal