Answer to Question 1
The placenta weighs between 1-2 pounds at term. It is a highly vascularized structure and has many important functions. The placenta transfers nutrients, hormones, oxygen, and other substances from mom to baby. In exchange, the placenta removes metabolic wastes from the fetus and allows passage back into the mother's blood for excretion by the mother's lungs and kidneys. The placenta is also a source of several hormones that serve a variety of functions during pregnancy.
Answer to Question 2
Teratogens are a broad group of environmental agents such as chemicals, drugs, infections, and/or radiation that negatively affect the normal course of cell growth and development in an unborn child. Fetal alcohol syndrome (FAS) or fetal alcohol effect (FAE) are the results of exposure to one of the most familiar teratogens, alcohol during pregnancy. FAS results in a small head circumference, unusual facial characteristics, and other physical deformities. Many infants are developmentally delayed. FAE is characterized by learning and behavior problems that are unfortunately not apparent until later in life.
36 weeks in the uterus
A schematic diagram of the functional cycle of the Na+–K+ pump
Literacy Development in the Early Years: Helping Children Read and Write
A single cell from an early-stage human embryo
How Rh differences can complicate pregnancy.