PSYB20H3 Chapter 3: PSYB20NOTESChapter3
Document Summary
During the embryonic period, the inner mass of the developing organism differentiates into three layers: the ectoderm: hair, nails, and parts of the teeth the outer layer of the skin and skin glands, and the sensory cells and the nervous system develop the mesoderm: forms into the muscles, skeleton, circulatory and excretory systems and inner skin layer the endoderm: comes the gastrointestinal tract, trachea, bronchial, eustachian tubes, glands, and vital organs (lungs, pancreas, and liver) The rapid development and differentiation that occur at this time make the embryo more susceptible during this period than any other to environmental assault exp. at 4th or 5th week of gestation, the neural folds (formations that evolve ultimately into the central nervous system) begin to close if something prevents them from closing properly the child will have spina bifida, a disorder in which the spinal cord and the membranes that protect it may protrude from the spinal column.
