Embryonic Period

Question 1

What weeks are included in the embryonic period?

Answer 1

Between weeks 3 and 8

Question 2

gastrulation

Answer 2

process by which cells from the epiblast migrate to form the primary germ layers (IMPORTANT)

Question 3

Primitive streak

Answer 3

starts formation in gastrulation, includes primitive node and primitive pit

Question 4

primitive node

Answer 4

cephalic end of the primitive streak, indentation doesn’t go all the way through the embryo

Question 5

primitive pit

Answer 5

depression in the node, end of the streak

Question 6

what are the 3 primary germ layers?

Answer 6

ectoderm, mesoderm, endoderm

Question 7

ectoderm

Answer 7

previous epiblast, nervous system and skin

Question 8

mesoderm

Answer 8

previous mesoblast cells that filled the middle, muscle and bone
cells between the epiblast and hypoblast layers become the primary germ layer

Question 9

endoderm

Answer 9

rapidly dividing cells that move downwards and get rid of hypoblast, linings

Question 10

invagination

Answer 10

inward movement of cells (rapid cell division and migration) form epiblast layer through primitive streak between epiblast and hypoblast layers

Question 11

what goes on during the embryonic disc formation?

Answer 11

umbilical cord formed, notochord (IMPORTANT) formed
embryonic disc

Question 12

notochord

Answer 12

sends signals to ectoderm, mesoderm, and endoderm to start to form into different organs

Question 13

What begins to form after the appearance of the notochord?

Answer 13

neural tube
causing ectoderm to start to form
IMPORTANT signaling structure

Question 14

neurulation

Answer 14

formation of the neural tube from overlying ectoderm cells

Question 15

what does the neural tube become?

Answer 15

central nervous system, causing ectoderm folding, becomes brain and spinal cord

Question 16

embryonic disc

Answer 16

flattened disk-shaped structure, folding happens in the early 3rd week

Question 17

cephalocaudal folding

Answer 17

head and tail fold, brings heart below oral region

Question 18

transverse folding

Answer 18

lateral folding, left and right sides of embryo curve toward midline, ectoderm on outside, endoderm on inside, mesoderm in middle

Question 19

organogenesis

Answer 19

organ development, most organ systems are complete by week 8

Question 20

teratogens

Answer 20

normal development of organs can be interfered with by agents (recreational drugs, alc, prescription meds)

Question 21

fetal period

Answer 21

week 9-birth, maturation and growth of tissues and organs