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
- endoderm inner layer digestive and respiratory
- mesoderm middle layer muscle and skeletal
- 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
- amnion
- umblical corc
- placenta
Amnion
bag/sac like contains amniotic fluid where embryo floats homeostasis → temp, humidity shockproof
Umbilical 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 prescription non-prescription 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, quality of sperm