Nick Robertson 9/13/15 Kines 199 Chapter 4 Book Notes Prenatal

Nick Robertson
Kines 199
Chapter 4 Book Notes
Prenatal Development
o Growth process starts as soon as fertilization
o Genes determine the same normal aspects of development
o The growing embryo is very sensitive to extrinsic factors which include the ambiotic sac
& nutrients the embryo receives.
o Extrinsic Factors such as abnormal pressure, viruses or sickeness & drugs will have
detrimental effects on the fetus.
 Proper nutrients enhance fetus growth
 Embryonic growth: 0-8 weeks
 Fetal growth 8 weeks- birth
Embryonic Development
o After conception, cells began to increase in # and differentiate, creating tissues and
o At 4 weeks, the heartbeat begins
o At 8 weeks, eyes, ears, mouth, nose, fingers, and toes are formed.
Fetal development
o From 8 weeks to birth, the fetal stage is characterized by further growth & cell
differentiation of the fetus
o Continued growth occurs in 2 ways: hyperplasia & hypertrophy
o Cephalocaudal: head and facial structures grow fastest, followed by upper body & lower
o Proximodistal: direction of growth starting from body towards extremities
o Plasticity: the ability for cells to take on a new function
Fetal nourishment
o Nourishment has the most unfluence on fetal development.
o Nourtished by diffusion of oxygen & nutrients between fetal and maternal blood.
Overall Growth
o Overall growth is just a continuation of pretanatal growth
o Major factor for growth timing & extent
o Girls often begin adolescent growth at age 9.
o Boys begin at age 11.