POSC 3210 Lecture Notes - Lecture 2: Impulsivity, Mitosis, Apoptosis
6 Mar 2019
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Document Summary
All humans originated from union of two gametes (sperm and egg) Gametes are produced through meiosis and contain 23 chromosomes; when united. Almost all eggs are formed prenatally; sperm productions continues throughout the life. End of week 1:zygote becomes implanted in the uterine wall. Day 4:cells arranged into hollow sphere= inner cell mass. During week 2:inner cell mass differentiates into 3 layers. 2= muscles, bones, circulatory system, internal organs. 3= digestive system, lungs, urinary tract, glands. After implantation neural tube created brain, spinal cord. Amniotic sac- membrane filled w clear, watery fluid, in which the fetus floats. Insulates and is for protection and temperature mantation. Placenta- special organ that permits the exchange of materials carried in the bloodstream of the fetus and the mother. Umbilical cord- blood vessels running from the placenta to the embryo and back again. Major development occurs in all organs and systems. Begin to specialize into 350 types of cells.
