Brain vessels enter the central nervous system through holes in the meningeal layers. The cells in the blood vessel walls are joined tightly to one another, forming the blood–brain barrier, which blocks the passage of many toxins and pathogens (though at the same time blocking antibodies and some drugs, thereby presenting special challenges in treatment of diseases of the brain). Neuroanatomists usually divide the vertebrate brain into six main regions: the telencephalon (cerebral hemispheres), diencephalon (thalamus and hypothalamus), mesencephalon (midbrain), cerebellum, pons, and medulla oblongata. Each of these areas has a complex internal structure. Some parts, such as the cerebral cortex
If We Are the Body not showing them there is a way?" "If We Are the Body" challenges the church to welcome outsiders and to "get more visibly involved in changing this world". "If We Are the Body" received positive reviews from music critics. Kim Jones of About.com noted it as a "highlight" from "Casting Crowns". Andy Argyrakis of "CCM Magazine" said that the song "commands attention" of lead singer Mark Hall. Belinda S. Ayers of Christian Broadcasting Network described it as "powerful" and "catchy". Steve Best of "Cross Rhythms" felt it was an example of Casting Crowns being "more... than rock bluster". Russ Breimeier