The brain controls the entire body. Some parts of the brain regulate basic functions. These include breathing, blood pressure, and heartbeat. Other parts control more complex functions, such as moving, thinking, speaking, and memory.
Under the scalp and the skull, a tough membrane (called the dura) surrounds the brain. Beneath the dura, cerebrospinal fluid (CSF) cushions the brain and circulates in the subarachnoid space. Arteries carry nutrients and oxygen-rich blood throughout the brain. Without this blood, brain tissue quickly dies. The brain consists of about 100 billion cells called neurons that allow it to perform its many functions.
Not pictured above is the forebrain which contains the thalamus, hypothalamus, and pituitary gland. The thalamus sends impulses from the sense organs to the cortex. The hypothalamus controls hunger, thirst, temperature,aggression, and sex drive. It also controls the pituitary gland, which controls the secretion of many hormones.