Embryogenesis and Development

Question 1

Fertilization

Answer 1

secondary oocyte travels to fallopian tube where it can bind to sperm; now is a diploid zygote

Question 2

Cleavage

Answer 2

after fertilization, zygote implants in uterus; undergoes rapid mitotic divisions; officially becomes an embryo; overall size doesn’t change-divides into progressively smaller cells that will later be able to differentiate into different cell types

Question 3

Blastulation

Answer 3

solid morula forms blastula, hollow ball of cells with fluid inner cavity

Question 4

morula

Answer 4

embryo becomes solid mass of cells after multiple divisions

Question 5

chorion

Answer 5

trophoblast cells of the blastula give rise to chorion which develops into the placenta

Question 6

umbilical cord

Answer 6

connects the embryo to placenta; has arteries that carry deoxygenated blood and waste to placenta for exchange

Question 7

gastrulation

Answer 7

generation of three distinct cell layers: ectoderm, mesoderm, endoderm

Question 8

Ectoderm

Answer 8

gives rise to epidermis, hair, nails, nose, mouth, anal canal, eye, nervous system, inner ear

Question 9

mesoderm

Answer 9

gives rise to musculoskeletal, circulatory, and excretory systems, gonads, muscular and connective tissues

Question 10

endoderm

Answer 10

digestive and respiratory tracts, including the lungs; pancreas, thyroid, bladder, urinary tract

Question 11

selective transcription

Answer 11

allows cells with same genes to develop into different cell types by only turning on the genes required to fulfill the specific function

Question 12

neurulation

Answer 12

development of nervous system, derived from ectoderm; neural folds on surface of ectoderm fuse into neural tube, which gives rise to cells of central nervous system

Question 13

Teratogens

Answer 13

substances that interfere with development of the embryo; includes alcohol, drugs, viruses, bacteria, environmental chemicals

Question 14

determination

Answer 14

commitment of a cell to have a particular function in the future; after determination, cell is committed to specific lineage, but hasnt yet performed its function

Question 15

differentiation

Answer 15

after cell’s fate has been determined, cells changes structure, function, and biochemistry in order to develop into that particular cell type

Question 16

Inducers

Answer 16

cell that secretes a signal intended for another cell; often are growth factors which promote differentiation and mitosis

Question 17

placenta

Answer 17

organ where nutrient, gas, and waste exchange occurs, mostly through diffusion; placental barrier provides immune protection ; oxygenation occurs in placenta, not lungs!

Question 18

fetal hemoglobin

Answer 18

has greater affinity for oxygen compared to adult hemoglobin; helps with the retention of oxygen in fetal circulation

Question 19

umbilical arteries

Answer 19

carry blood away from fetus towards the placenta

Question 20

umbilical veins

Answer 20

carries blood towards the fetus from the placenta

Question 21

2 shunts that reroute blood from fetal lungs

Answer 21

foramen ovale: one-way valve that connects right atrium to left atrium, so blood flows into left atrium instead of right ventricle and out through aorta; ductus arteriosus: shunts blood from pulmonary artery to aorta

Question 22

shunt that keeps blood from fetal liver

Answer 22

ductus venosus: shunts blood returning from placenta directly to inferior vena cava

Question 23

First trimester

Answer 23

major organs begin to develop, heart begins to beat, skeleton begins to harden, brain becomes fairly developed, embryo becomes known as a fetus

Question 24

Second trimester

Answer 24

fetus undergoes a lot of growth, begins to move within amniotic fluid, face becomes more developed

Question 25

Third trimester

Answer 25

rapid growth and brain development, antibodies transferred from mother to fetus for later protection; growth slows as fetus has less room to move around

Question 26

Birth

Answer 26

vaginal childbirth accomplished through contractions of uterine smooth muscle, coordinated by prostaglandins and oxytocin; first amniotic sac ruptures, then strong contractions and birth of fetus, last- expulsion of placenta, umbilical cord