Module 9 - Human Development and Anatomy through the Lifespan Flashcards
Embryonic period
from fertilization to week 8
Organogenesis
process of organ formation
Morphogenesis
the development of body shape and organization; completed by day 28
Cephalocaudal folding
head and tail folding, due to rapidly growing brain, creates the future head and tail regions
Transverse folding
-lateral folding; left and right sides of embryo curve toward midline
-forms torso and primitive gut
Teratogens
-Environmental agents that can disrupt development and cause congenital abnormalities (Drugs, alcohol, radiation, some viruses (Zika), some medications etc)
-Cause the most harm to a specific organ system or region during its peak developmental time
-Weeks 3-8 are particularly vulnerable
Fetal period
from week nine until birth
Critical periods
times when development is occurring very rapidly in a given structure
Windows of vulnerability
when an incident or exposure that disrupts that development even a small amount can have greater consequences than during other times in development
T/F: Organ systems do not begin to form until the beginning of the fetal period
False
T/F: All tissues of the body will form from the three layers of the disc that is present during the third week of embryonic development
True
T/F: Folic acid is critical for nervous system development
True
T/F: The heart begins to beat on day 21 or 22 post-fertilization
True
T/F: All organ systems are present in a rudimentary form by the end of week 8
True
T/F: The embryo enters the uterus and implants within 24 hours of fertilization
False
What occurs during week 1?
-embryo enters the uterus
-marked by repeated, rapid cell division
What occurs during week 2?
-amniotic fluid begins to form
-placental development begins
What occurs during week 3?
-organ systems begin to form
-the nervous system begins to form
-caudal and cranial ends are established, even though they aren’t clearly visible
-the embryo takes the form of a three-layered oval-shaped disc
What occurs during week 4?
-all organ systems exist and are in process of forming, though they have a long way to go before they are even considered rudimentary structures
-cephalocaudal folding occurs
-the limbs begin to form
-transverse folding occurs
What occurs during week 7-8?
-separate fingers and toes are formed
-muscles are capable of contraction, though movement in uncontrolled
