Embryogenesis and Development (3)

Question 1

Cortical reaction

Answer 1

When first sperm penetrates it causes release of calcium ion, which prevents other sperms from fertilizing the egg and increase the metabolic rate of resulting of diploid zygote.

Question 2

Fraternal (dizygotic) twins

Answer 2

results from the fertilization of two eggs by two different sperm.

Question 3

Identical (monozygotic) twins

Answer 3

results from the splitting of a zygote in two. Monozygotic twins can be classified by the placenta structures.

mono vs. diamoniotic –> sharing same amnion
mono vs. dichronic –> sharing same chorion

Question 4

Indeterminate cleavage

Answer 4

results in cells that are capable of becoming any cell in the organism

Question 5

Determinate cleavage

Answer 5

cells that are commited to differentiating into a specific cell type. or a whole organism

Question 6

Morula

Answer 6

solid mass of cells seen in early development

Question 7

Blastula (Blastocyst)

Answer 7

fluid-filled center called blastoceol and has two different structures: trophoblast, inner cell mass

trophoblast: becomes placental structures
inner cell mass: becomes the developing organism

Question 8

Implantation

Answer 8

occurs during the blastula stage. Implants in endometerial lining and forms the placenta

Question 9

Chorion

Answer 9

contrains chorionic vili, which penetrates the endometerium and create the interface between maternal and fetal blood. ( will develop into placenta later)

Question 10

Allantois

Answer 10

involved in early fluid exchange between embryo and yolk sac ( occurs before placenta is established)

Question 11

amnion

Answer 11

lies inside the chrion and produces amniotic fluid

Question 12

Gastrulation

Answer 12

generation of three distancts cell layer.

Question 13

Deutrosome vs. Protostomes

Answer 13

Deutrostomes (Humans)- blastophore will develop into anus first.

Protostomes- blastophore will develop into mouth first

Question 14

Ectoderm
Mesoderm
Endoderm

Answer 14

Ectoderm- give rise to outer layer, and nervous system
Mesoderm- give rise to msucloskeletal and circulatory, and excertory system.
Endoderm- forms the epithelial lining of digesting and respiratory tracts, including the lungs.

Question 15

Selective transcription

Answer 15

gene needed for the particular cell types are transcribed.

(pancreatic islet cells the genes are produce specific horomones are turned on, while these genes are turned off in other cell types.

Question 16

Neurulation

Answer 16

Neural plate –> Neural fold –> Neural groove —> Neural tube

Question 17

Neural tube

Answer 17

give rise to CNS

Question 18

Neural crest cells

Answer 18

give rise to PNS

Question 19

Teratogens

Answer 19

substances that interfere with development, causing defects or even death of the developing embryo.

Question 20

Stages of zygote to gastrula

Answer 20

zygote - 2 - 4- 8- 16 Cell embryo - morula - bastula - gastrula

Question 21

Determination

Answer 21

commitment to a specfic cell lineage, which may be accomplished by uneven segregation of cellular material during mitosis or with morphogens.

Question 22

Morphogens

Answer 22

promote development down to a specific cell line. To respond to a specific morphogen, a cell must have competency.

Question 23

Differentiation

Answer 23

refers to changes a cell undergoes due to selective transcription to take on characteristics appropriate to its cell line.

Question 24

Stem cells

Answer 24

capable of developing into various cell types. Can be classified by potency.

Totipotent cells- able to differentiate into all cell types, including the three germ layers and placental structures.

Puripotent cells- able to differentiate into all three germ cell layers and their derivatives.

Multipotent cells- able to differentiate only into a specific subset of cell types.

Question 25

Inducer

Answer 25

releases factors to promote the differentiation of a competent responder.

Question 26

Autocrine

Answer 26

signals act on the same cell that released the signal

Question 27

Paracrine

Answer 27

signals act on local cells

Question 28

Juxtacrine

Answer 28

signals act through direct stimulation of adjacent cells

involve cell directly stimulating receptors of an adjacent cell.

Question 29

Endocrine

Answer 29

signals act on distant tissues after travelling through blood stream.

Question 30

growth factors

Answer 30

peptides that promote differentiation and mitosis in certain tissues.

Question 31

reciprocal induction

Answer 31

if two tissues both induces further differentiation in each other.

Question 32

Apoptosis

Answer 32

cell death via formation of apoptotic blebs that can be absorbed and digested by other cells.

Question 33

Regenrative capacity

Answer 33

ability of an organism to regrow certain parts of the body

complete regeneration - lost or damaged replaced with identitcal tissues.

incomplete regenration - newly formed tissue isnt identitical in strucute or in function.

Question 34

Senescence

Answer 34

result of multiple molecular and metabolic processes, most notably, the shortening of telomeres during the cell division.

Question 35

Fetal hemoglobin (HbF)

Answer 35

has higher affinity for oxygen than adult hemoglobin HbA.

Question 36

Placenta ( endocrine function)

Answer 36

secretes estrogen, progesterone, and hCG

Question 37

umbilical arteries vs. umbilical veins

Answer 37

umbilical arteries - carry deoxygenated blood from fetus to placenta

umbilical vein - carry oxygenated blood from placenta to fetus.

Question 38

Thre shunts:

Foramen ovale
Ductus arteriosus
Ductus venosus

Answer 38

Foramen ovale - connects the right atrium to the left atrium, bypassing the lungs

Ductus arteriosus- connects the pulmonary artery to the aorta, bypassing the lungs

Ductus venosus - connects the umbilical vein to the inferior vena cava, bypassing the liver.

Blood flow for the fetus: blood flow in ductus arteriosus is from the aorta to the pulmonary artery.

Question 39

First trimester

Answer 39

organogensis occurs ( heart, eyes, gonads, limbs, liver, brain)

Question 40

Second trimester

Answer 40

growth occurs, movement begins, face becomes distanctly human, digate elongate

Question 41

Third trimester

Answer 41

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