BIO Ch. 3 Embryogenesis & Development

Question 2

What is the pathway of sperm penetrating an egg?

Answer 2

The sperm uses the acrosomal enzymes to penetrate the corona radiata and zona pellucida, causing a release of calcium ions, which prevents additional sperm from fertilizing the egg and increasing the metabolic rate of the resulting diploid zygote. Once it contacts the oocyte’s plasma membrane, the sperm establishes the acrosomal apparatus and injects its pronucleus.

Question 3

Where does fertilization occur?

Answer 3

in the ampulla of the fallopian tube

Question 4

What is the diff b/w di and monozygotic twins?

Answer 4

fraternal (dizygotic) twins results from the fertilization of 2 eggs by 2 different sperm, while identical (monozygotic) results from the slitting of a zygote into 2

Question 5

When does a zygote become an embryo?

Answer 5

after the first cleavage (divisions of embryonic cells) because it is no longer unicellular

Question 6

What is the diff b/w indeterminate and determinate cleavage?

Answer 6

indeterminate cleavage results in ells that are capable of becoming any cell in the organism, while determinate results in cells that are committed to differentiating into specific cell types

Question 7

What are the 2 different cell types of the blastula?

Answer 7

blastocysts have 2 different cell types - trophoblast, which becomes the placental structure, and inner cell mass, which becomes the developing organism

Question 8

What is the role of the aminon?

Answer 8

the amnion lies in the chorion and produces amniotic fluid

Question 8

What is the role of the yolk sac?

Answer 8

supports the embryo before the placenta is estbalished

Question 9

What are the 3 primary germ layers of the arhenteron?

Answer 9

the ecto, meso and endoderm

Question 10

What does the ectoderm become?

Answer 10

epidermis, hair, nails and epithelia of the nose, mouth, and anal canal, as well as the lens of the eyes, and nervous system including the adrenal medulla

Question 11

What does the mesoderm become?

Answer 11

musculoskeletal, circulatory and excretory systems, and also gives rise to the gonads and the muscular and connective tissue layers of the digestive tracts and respiratory systems as well as the adrenal cortex

Question 12

What does the endoderm become?

Answer 12

becomes the epithelial lining of the respiratory an digestive tracts, and parts of the pancreas, thyroid, bladder, and distal urinary tracts

Question 13

What is neurulation?

Answer 13

the development of the nervous system begins after the formation of the 3 germ layers

Question 14

How does the neural tube form?

Answer 14

the neural folds fuse to form the neural tube, which becomes the CNS

Question 15

What do the neural crest cells become?

Answer 15

it becomes the peripheral Nervous system (sensory ganglia, autonomic ganglia, adrenal medulla, and Schwan cells) as well as specific cell types in other tissues (calcium-producing cells of the thyroid, melanocytes in the skin, and others)

Question 16

What are teratogens?

Answer 16

substances that interfere with development causing defects or death of the developing embryo. teratogens include alcohol, certain prescription drugs, viruses, bacteria, and environmental chemicals.

Question 17

What are the 3 classifications of stem cells?

Answer 17

totipotent, pluripotent, and mutlipoetent cells

Question 18

What are totipotent stem cells able to differentiate into?

Answer 18

able to differentiate into all cell types including the 3 germ layers and placental strictures

Question 19

What are pluripotent stem cells able to differentiate into?

Answer 19

able to differentiate into all cell types including the 3 germ layers and their derivatives

Question 20

What are multipotent stem cells able to differentiate into?

Answer 20

able to differentiate only into specific subsets of cell types

Question 21

What does an autocrine signal act on?

Answer 21

autocrine signal acts on the same cells that release the signal

Question 22

What does a paracrine signal act on?

Answer 22

paracrine signals act on the cells in the local area via diffusions

Question 23

What does a juxtacrine signal act on?

Answer 23

juxtacrine signal acts through direct stimulation of the adjacent cells, but the signal does not spread through diffusion

Question 24

What does an endocrine signal act on?

Answer 24

endocrine signal acts on distant tissues after traveling through the bloodstream

Question 25

When is apoptosis useful?

Answer 25

for sculpting certain anatomical structures such as removing the webbing between digits and a perforate anus

Question 26

What are the functions of the placenta?

Answer 26

fetal hemoglobin (has a higher affinity than adult blood), nutrients, gas (CO2 and O2), and waste exchange, serve as immune protection against pathogens, antibodies are transferred from mother to child and secrete estrogen, progesterone, and human chorionic gonadotropin hormones

Question 27

What is the diff b/w the umbilical artery and vein?

Answer 27

umbilical arteries carry deoxygenated blood from the fetus to the placenta; the umbilical vein carries oxygenated blood from the placenta back to the fetus

Question 28

What is the diff b/w fetal and adult circulatory system?

Answer 28

the fetal circulatory system has shunts, and the right side of the heart is at higher pressure during prenatal life than the left side so that blood will shunt from the pulmonary circulation to the system circulation

Question 29

What are the 3 fetal shunts?

Answer 29

the foreman oval, ductus arteriosus and ductus venosus

Question 30

What does the foreman oval shunt bypass?

Answer 30

the foreman oval connects the right atrium to the left atrium, bypassing the lungs

Question 31

What does the ductus arteriosus oval shunt bypass?

Answer 31

the ductus arteriosus connects the pulmonary artery to the aorta, bypassing the lunges

Question 32

What does the ductus venosus shunt bypass?

Answer 32

the ductus venosus connects the umbilical veins to the inferior vena cava, bypassing the liver

Question 33

What happens during the first trimester?

Answer 33

organogenesis occurs - development of the heart, eyes, gonads, limbs, liver, and brain

Question 34

What happens during the second trimester?

Answer 34

growth continues, the movement begins, the face becomes distinctly human and the digits elongate

Question 35

What happens during the third trimester?

Answer 35

rapid growth and brain development continues, and there is a transfer of antibodies to the fetus

Question 36

What causes uterine contractions?

Answer 36

release of prostaglandins and oxytocin

Question 37

What is the role of estrogen and progesterone?

Answer 37

during pregnancy, the placenta produces estrogen and progesterone to maintain the endometrium

Question 38

What is incomplete regeneration?

Answer 38

occurs when newly formed tissues are not identical in structure and function to those injured or lost tissues.

Question 39

What are the 3 cell divisions of embryo formation?

Answer 39

after the first division, the embryo consists of a solid ball of cells known as a morula, then a following center forms, creating the blastula. finally, as the cells begin to differentiate into the 3 germ layers, the embryo is considered a gastrula

Question 40

What is the last organ to form in the fetus?

Answer 40

the lungs because the fetus is suspended in amniotic fluid, thus, blood exchange is bypassed the pulmonary circulation into system circulation