This week we learned a little about the different neurotransmitter systems that exist in the body and some of the techniques used to identify and study these systems. Included in these systems are recepetor subtypes. Two different neurotransmitters cannot bind to the same receptor, but one neurotransmitter can bind to many different receptors - these are called receptor subtypes. Receptor subtypes allow a neurotransmitter to have different affects in different parts of the nervous system (excitatory or inhibatory). We also learned about the structure and development of the nervous system. As an embryo one begins as a flat disk and is made up of three layers - endoderm, mesoderm and ectoderm. During development the ectoderm differentiates in order to become the nervous system and skin in a fully developed organism. It begins by forming a groove whose walls eventually fuse to become the neural tube. The neural tube then differentiates to become the central nervous system. The peripheral nervous system is derived from the neural crest which lies lateral to tne neural tube.
At the rostral, or front, end of the neural tube three vesicles form which will differentiate into the brain. The frontmost vesicle is called the prosencephalon which develops into the forebrain, the middle vesicle is the mesencephalon, which develops into the midbrain and the last vesicle is the rhombencephalon which develops into the hindbrain.