The nervous system has two major divisions, the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS consists of the brain, spinal cord, optic nerve and retina, and contains the majority of neuronal cell bodies. The PNS…
Cells evolved as single, free-living organisms, but natural selection favoured more complex communities of cells, multicellular organisms, where groups of cells specialize during development to carry out specific functions for the body as a whole. This allowed the emergence of…
Cell Structure General characteristics of cells The shapes of mammalian cells vary widely depending on their interactions with each other, their extracellular environment and internal structures. Their surfaces are often highly folded when absorptive or transport functions take place across…