Phases of Prenatal Development

#lifespan #biology

Period of Zygote / Germinal (0-3 weeks)

begins at conception; unity of two gametes, Fertilisation sperm and egg cell form a zygote zygote multiplies and travels from fallopian tube to uterine wall zygote -> blastocyst

Blastocyst

has three layers

  1. endoderm inner layer digestive and respiratory

  2. mesoderm middle layer muscle and skeletal

  3. ectoderm outer layer nervous system and skin

implantation takes place

Period of Embryo / Embryonic (3 weeks - 9 weeks)

after implantation cells now form an embryo development of brain; structure of forebrain, midbrain, and hindbrain heart begins to develop and pulse arms and legs start to form

Period of Fetus/ Fetal (9th week till birth)

sex determined around 9 weeks fetus will be able to move limbs nails, lashes, hair grow most growth weight and length wise happens during this period

life support systems

  1. amnion
  2. umblical corc
  3. placenta

Amnion

bag/sac like contains amniotic fluid where embryo floats homeostasis -> temp, humidity shockproof

Umblical cord

2 arteries and 1 vein connects placenta and baby

Placenta

Support system for baby disc shaped supplies necessary nutrients and other material needed takes away toxic waste from the processes (digestive)

Trimesters

3 trimesters - 9 months each trimester = 3 months

First trimester becomes a fetus; major organ systems develop morning sickness, fatigue

Second trimester feel movement as the fetus flips and turns can hear, see,

third trimester

Teratogens

etymology - Greek word teratos = monster

substances that interfere with normal fetal development and cause disabilities

Drugs (both prescription, non-prescription and recreational)

Incompatible Blood types (Rhesus factor) blood can be rh positive or rh negative

Environmental Hazards radiation toxic waste pesticide

Maternal illnesses rubella, syphilis, AIDS, herpes, diabetes

Maternal Diet

Stress

Age

Damaged sperms