Chpt. 3

Question 1

Fertilization

Answer 1

the joining of a sperm and an ovum in the ampulla of the fallopian tube.
Sperm uses acrosomal enzymes to penetrate the corona radiata and zona pellucida. Once in contact with oocyte’s plasma membrane, the sperm establishes the acrosomal apparatus and injects its pronucleus. After sperm meets egg, calcium ions are released to prevent more sperm from fertilizing the egg and increasing metabolic rate of resulting diploid zygote. Called the cortical reaction.

Question 2

Fraternal(dizygotic) twins vs Identical(monozygotic) twins

Answer 2

Fraternal: fertilization of two eggs by two different sperm.
Identical: results from the splitting of a zygote in two. Can be classified by placental structures: mono- vs. diamniotic(share vs have own amnion) and mono- vs. dichorionic(share vs have own chorion)

Question 3

Cleavage

Answer 3

the early divisions of cells in the embryo that produces large number of small cells. Zygote becomes embryo after first cleavage.

Question 4

Indeterminate cleavage vs determinate cleavage

Answer 4

Indeterminate: results in cells that are capable of becoming any cell in the organism
Determinate: cells are committed to differentiating into a specific cell type

Question 5

Morula

Answer 5

solid mass of cells seen in early development

Question 6

Blastula(blastocyst)

Answer 6

has a fluid-filled center called a blastocoel and has two different structures: trophoblast –> becomes placenta and inner cell mass –> becomes organism

Blastula implants in the endometrial lining and forms placenta

Question 7

Chorion

Answer 7

contains chorionic villia, which penetrate the endometrium and create the interface between maternal and fetal blood.

Question 8

Allantois

Answer 8

involved in the fluid exchange between embryo and yolk sac. Embryo supported by yolk sac before placenta is formed

Question 9

amnion

Answer 9

produced amniotic fluid. Located inside the chorion.

Question 10

Umbilical cord

Answer 10

connection between placenta and developing organism

Question 11

Gastrulation

Answer 11

Process where portion of blastula comes the archenteron which contacts opposite side of blastula thus forming a blastopore and three primary germ layers.
Ectoderm: becomes epidermis, hair, nails, and the epithelia of the nose, mouth and anal canal, as well as the nervous system and lens of the eye
Mesoderm: becomes musculoskeletal, circulatory, and excretory systems. Also gives rise to the gonads and the muscular and connective tissue layers of the digestive and respiratory system, and adrenal cortex
Endoderm: becomes epithelial lining of the respiratory and digestive tracts and parts of the pancreas, thyroid, bladder, and distal urinary tracts.

Question 12

Neurulation

Answer 12

development of the nervous system after gastrulation.
Notochord induces a group of overlying ectodermnal cells to form neural folds surrounding a neural groove, which then turns into neural tube –> becomes CNS. The tip of each neural fold contains neural crest cells –> becomes PNS

Question 13

Teratogens

Answer 13

substance that interfere with development, causing defects or death of embryo. (ex. alcohol, some drugs, viruses, bacteria)

Question 14

determination

Answer 14

commitment to a specific cell lineage. May be accomplished by uneven segregation of cellular material during mitosis or with morphogens.

Question 15

Differentiation

Answer 15

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

Question 16

Stem cells

Answer 16

cell that are capable of developing into various cell types. Classified by potency

Question 17

Stem cells potency

Answer 17

Totipotent cells: able to differentiate into all cell types, including the three germ layers and placental structures.
Pluripotent cells: able to differentiate into all three of the germ layers and their derivatives
multipotent cells: able to differentiate only into specific subset of cell types.

Question 18

Signaling methods

Answer 18

autocrine: signals act on the same cell that released the signal
paracrine: signals act on the same cell that released the signal
juxtacrine: signals act through direct stimulation of adjacent cells.
Endocrine signals act on distant tissues after traveling through the bloodstream.

Question 19

growth factors

Answer 19

peptides that promote differentialtion and mitosis in certain tissues

Question 20

reciprocal induction

Answer 20

if two tissues both induce further differentiation in each other

Question 21

Apoptosis

Answer 21

programmed cell death via formation of apoptotic blebs

Question 22

regenerative capacity

Answer 22

ability of an organism to regrow certain parts of the body. Liver high, heart low

Question 23

Senescence

Answer 23

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

Question 24

Fetal circulation

Answer 24

nutrient, gas, and waste exchange through placenta

oxygen and carbon dioxide are passively exchanged due to concentration gradients.

Fetal hemoglobin(HbF) has higher affinity for oxygen.

Placenta serves as barrier agains pathogens and transfer antibodies. Also acts as endocrine functions, secreting estrogen, progesterone, and human chorionic gonadotropin(hCG)

Question 25

umbilical arteries vs vein

Answer 25

arteries: carry deoxygenated blood from fetus to the placenta; Vein: carry oxygenated blood to fetus

Question 26

fetal circulatory shunts

Answer 26

Foramen ovale: connects right atrium to left atrium, bypassing the lungs Ductus arteriosus: connects the pulmonary artery to the aorta, bypassing the lungs ducts venosus: connects the umbilical vein to the inferior vena cava bypassing the liver

Question 27

First trimester

Answer 27

organogensis occurs: development of heart eyes, gonads, limbs, liver, brain

Question 28

Second trimester

Answer 28

Tremendous growth occurs, movement begins, the face becomes human and digits elongate

Question 29

third trimester

Answer 29

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

Question 30

Birth

Answer 30

cervix thins out and the amniotic sac ruptures. Then uterine contractions, coordinated by prostaglandins and oxytocin, result in birth of fetus then placenta and umbilical cord are expelled.