PS275 Study Guide - Midterm Guide: Fetus, Primitive Reflexes, Rh Blood Group System
Document Summary
Blastocyst up until 4 days, then becomes zygote. Inner layer of blastocyst becomes embryo and outlater layer becomes tissue. Placenta is born, site of all metabolic transactions that sustain embryo. All major organs form and heart begins to beat. Ectoderm = outer layer, nervous system, skin, hair, brain, spinal cord. Endoderm: inner layer, becomes digestive system, lungs, urinary tract, other vital organs. All major organs begin to function, rapid growth and refinement and become interconnected. Sex is determined by end of 3rd month. Age of vitality: point at which survival outside uterus is possible, 22-28 weeks. Perinatal environment: environment surrounding birth, social environment after baby is born, meds given to mother. 1st stage of childbirth: labour, contractions, ends when cervix has fully dilated. 2nd stage: delivery, starts when head of fetus is positioned at cervical opening and ends when baby emerges from mother. 3rd stage: uterus once again contracts and expels placenta from mother"s body.
