Chapter 27- Human Development

Question 1

What is the process called when a blastocyst attaches to the uterine wall?

Answer 1

Implantation

Question 2

What is pregnancy that occurs outside of the uterus?

Answer 2

Ectopic

Question 3

What happens if an oocyte is fertilized by more than one sperm?

Answer 3

The zygote will be non-viable

Question 4

How many germ layers are created by gastrulation?

Answer 4

3

Question 5

When does the oocyte complete meiosis?

Answer 5

Upon contact with spermatozoa

Question 6

What layer of the blastocyst will form the placenta?

Answer 6

Outer layer (trophoblast)

Question 7

What do we call the first 9 weeks of development?

Answer 7

Embryonic stage

Question 8

Which germ layer forms the skeletal system?

Answer 8

Both mesoderm and ectoderm

Question 9

What are the three stages of development?

Answer 9

Pre-embryonic, embryonic and fetal

Question 10

Where does fertilization of an oocyte occur?

Answer 10

In the uterine tube

Question 11

What is the cortical reaction? What does it prevent?

Answer 11

It is a release of enzymes from cortical granules. Destroys sperm-binding receptors so that no more sperm may enter the oocyte

Question 12

What causes completion of meiosis?

Answer 12

Fertilization

Question 13

What is amphimixis?

Answer 13

Moment of conception

Question 14

What is a zygote and how many chromosomes does it have?

Answer 14

Fertilized sex cell with 46 chromosomes

Question 15

Which gamete provides organelles and cytoplasm to the zygote?

Answer 15

Oocytes

Question 16

What is gestation?

Answer 16

Time spent in prenatal development

Question 17

What happens during the first trimester?

Answer 17

Embryo development and rudimentary organs develop

Question 18

What happens during the second trimester?

Answer 18

Development of organs and organ systems. Body shape and proportions change

Question 19

What happens during the third trimester?

Answer 19

Rapid fetal growth, most organs are fully functional

Question 20

Which stage is most critical during pregnancy?

Answer 20

First trimester

Question 21

What happens during differentiation of blastocysts?

Answer 21

The new cells become specific tissues which are bound for specific function like bone, skin and heart muscle

Question 22

Where does implantation occur?

Answer 22

Endometrium of uterus

Question 23

Which part of the blastocyst becomes the embryo?

Answer 23

The inner cell mass

Question 24

What is the basic process of gastrulation?

Answer 24

Rearrangement of cells of embryonic disc to form a trilaminar (or 3 layered) embryonic disc.

Creation of the 3rd (middle) germ layer

Question 25

What are the three germ layers?

Answer 25

Ectoderm, mesoderm, endoderm

Question 26

What is the umbilical cord and how is it formed?

Answer 26

Vessels that connect the growing fetus to the mother’s body. Early blood vessels in allantois become umbilical vessels.

Tissues around allantois become connecting stalk that forms the remainder of the cord

Question 27

What tissues develop from the ectoderm?

Answer 27

Nervous system, epidermis, epithelium of nasal, oral and anal canals, eye muscles, ears, salivary glands, Arsenal medulla, pituitary and pineal glands

Question 28

What tissues develop from the mesoderm?

Answer 28

Skeleton, cartilage and connective tissues. Skeletal, cardiac and smooth muscle. Blood/vessels and lymph, bone marrow, lymphatic tissue, kidneys and ureters. Gonads and genital ducts

Question 29

What tissues develop from the endoderm?

Answer 29

Epithelium of digestive tract, respiratory tract, bladder let and urethra, accessory reproductive and digestive glands, thyroid and thymus

Question 30

What are the hormones secreted by syncytial trophoblast?

Answer 30

Human chorionic gonadotropin, progesterone, human placental lactogen, placental prolactin, relaxin, estrogens

Prevents degeneration if corpus luteum