AP BIOLOGY

Detailed explanation-1: -Approximately 86 billion neurons in the human brain. The latest estimates for the number of stars in the Milky Way is somewhere between 200 and 400 billion. So close, but the human brain certainly doesn’t quite stack up! But why do scientists think there are 86 billion neurons?

Detailed explanation-2: -With more recent estimates of 21–26 billion neurons in the cerebral cortex (Pelvig et al., 2008) and 101 billion neurons in the cerebellum (Andersen et al., 1992), however, the total number of neurons in the human brain would increase to over 120 billion neurons.

Detailed explanation-3: -About 75% of the brain is made up of water This means that dehydration, even as small as 2%, can have a negative effect on brain functions. Dehydration and a loss of sodium and electrolytes can cause acute changes in memory and attention.

Detailed explanation-4: -How many cells are in the human brain? There are roughly 171 billion cells in the average male brain according to new research, including about 86 billion neurons . Neurons are cells that help transmit signals throughout the brain.

Detailed explanation-5: -The preponderance of the cerebral cortex (which, with its supporting structures, makes up approximately 80 percent of the brain’s total volume) is actually a recent development in the course of evolution.