In a nursing class the instructor explains the vulnerability of the organ systems during formation, such as the respiratory and circulatory systems, to environmental influences. this process of organ formation is called

organogenesis

Explanation:

Organogenesis is defined as a process in which the three germ layers differentiate further to form several organs.  

The embryonic stem cell is responsible for determining the ultimate cell type. During this process, neural system is formed and several morphological changes occur. The neural system further differentiates and develops to form neural tube and ultimately converts into brain and spinal cord. While folds and dense clusters are formed in the embryo that later form organs.