reproduction and development - part b

Question 1

embryonic period of development

Answer 1

• first 8 weeks
• tissues and organs form
• structures that support and nourish the embryo also form

Question 2

fetal period of development

Answer 2

• 9th week –> birth
• organs begin to function and coordinate to form organ systems

Question 3

fertilization

Answer 3

• when the sperm and ovum unite
• in the fallopian tube
• sperm + ovum = zygote

Question 4

cleavage

Answer 4

• cell division without the enlargement of cells
  2 then 4 then 8 cells

Question 5

morula

Answer 5

• 16 cells
• not part of the cleavage stage

Question 6

blastocyst

Answer 6

• has a trophoblast
• has an inner cell mass

Question 7

trophoblast

Answer 7

• develops into chorion
• develops into placenta
• part of the blastocyst
• secretes the hormone hCG

Question 8

inner cell mass

Answer 8

develops into the embryo
- part of the blastocyst

Question 9

implantation

Answer 9

• the embedding of the blastocyst into the endometrium
• enzymes secreted by the trophoblast digest some of the tissues and blood vessels of the endometrium

Question 10

hCG

Answer 10

• human chorionic gonadotropin
• maintains the corpus luteum
• levels of hCG begin to decline after first two months

Question 11

granulation and tissue formation

Answer 11

-during the second week of development

Question 12

amniotic cavity

Answer 12

space between the inner cell mass and trophoblast

Question 13

embryonic disc

Answer 13

• comes from the inner cell mass
• has two layers:
  ectoderm and endoderm

Question 14

gastrulation

Answer 14

• the process of forming the primary germ layers (meso, endo, ecto)

Question 15

gastrula

Answer 15

a developing embryo

Question 16

progression of embryonic development

Answer 16

zygote –> morula –> blastocyst –> gastrula

Question 17

morphogenesis

Answer 17

• the start is marked by gastrulation
• series of events that form distinct structures of the developing organism
• is dependant on embryonic cells being able ot become different

Question 18

ectoderm layer

Answer 18

• nervous system
• epidermis

Question 19

mesoderm layer

Answer 19

• muscles
• skeleton
• reproductive organs

Question 20

endoderm layer

Answer 20

• endocrine glands
• lining of digestive + respiratory systems

Question 21

skeleton formation

Answer 21

• mesoderm cells come together to form a rod like structure called the notochord

Question 22

notochord

Answer 22

• develops into the skeleton/ backbone
• a rod of mesoderm cells

Question 23

neurulation

Answer 23

• ectoderm above the notochord begin to thicken
• folds develop amd fuse to make the neural tube
• will develop into the brain and spinal chord

Question 24

amnion

Answer 24

• transparent sac
• filled with fluid
• protects embryo from trauma and temp fluctuations

Question 25

yolk sac

Answer 25

- contributes to the digestive tract formation - produces the 1st blood cells and future egg/sperm - only attatched to the baby not the mom

Question 26

allantois

Answer 26

- forms foundation of the umbilical cord

Question 27

chorion

Answer 27

- outermost membrane - encloses everything else - will form the fetal portion of the placenta

Question 28

chorionic villi

Answer 28

- establish the beginnings of the placenta

Question 29

placenta

Answer 29

disk shaped organ that is rich in blood vessels - fully developed by week 10 - blood systems DO NOT mix - nutrients and oxygen diffuse from the mother's circulatory system to the baby - wastes from baby go to mother - comes from the trophoblast layer two parts: - embryonic/fetal portion - maternal portion

Question 30

embryonic/fetal portion of placenta

Answer 30

chorion tissue comes from embryo

Question 31

maternal portion of the placenta

Answer 31

blood pools form the mother's circulatory system

Question 32

umbilical cord

Answer 32

- forms near 8th week - has 2 arteries and 1 vein going to placenta/mom

Question 33

embryonic period

Answer 33

- time of morphogenesis

Question 34

fetal period

Answer 34

time of growth and refinement

Question 35

gestation

Answer 35

period of time between fertilization and birth

Question 36

human gestational period

Answer 36

- 40 weeks - fetus considered "full term"

Question 37

teratogens

Answer 37

any agents that cause a structural abnormality in the baby - ex. smoking or alcohol

Question 38

first trimester

Answer 38

- weeks 1-12 - most sensitive to drugs/alcohol - formation

Question 39

fetal period of development begins

Answer 39

- formation - part of 1st trimester - weeks 9-12 - body growth accelerates - end of week 12: ecternal genetalia is distinguishable

Question 40

second trimester

Answer 40

- weeks 13-24 - framing/walls - nervous system starts to function - mother begins to feel movement

Question 41

third trimester

Answer 41

- weeks 25-38 - finishing touches - body mass increases - digestive and respiratory tracts form LAST