BRAIN ANATOMYSurrounded by the cranium and the meninges and floating in a lipid pool of fluid known as cerebral spinal fluid one finds the brain, the epicenter of all communication. Due to its intense metabolic rate, the brain is highly sensitive to the deprivation of oxygen and requires nearly constant supply to prevent damage. The central nervous system is quite delicate and thus it is encompassed in protective boney structures, the cranium and the flexible vertebral column.
BRAIN STRUCTUREBetween the bone and the central nervous system, there is a fine layer or protective connective tissue. Cerebral spinal fluid not only adds additional protection for the brain, but also adds an element of protection to the spinal cord. This fluid is found in the cranium as well as the central canal of the spinal column as well as the subarachnoid space which surrounds the entire central nervous system.
Gray and white matter makes up the central nervous system. Grey matter is comprised of primarily nerve cell bodies and dendrite or bundles of unmyelinated axons and neuroglia. The gray matter of the brain is the outermost complicated cortex layer of the cerebellum and the cerebrum. Buried deep within the white matter of the brain, gray matter can be found as specialized clusters of nerve cells which are known as nuclei.
Communication tracts within the central nervous system are developed by the white matter. This white matter is formed by aggregations of dendrites, myelinated axons, and the occasional neuroglia.
The human brain weighs between 3 and 3.5 pounds. Nearly one billion neurons create the brain and serve as its functional communication. Just as is true with the rest of the central nervous system, the synapses between the dendrites and the axons make communication between neurons possible. Neuropeptides are the specialized neurotransmitters within the brain. Specific mental functions would not exist without the introduction of the neuropeptides.
BRAIN FUNCTIONSThe brain’s high demand for oxygen and nutrients is reflected in its domination of the body’s percentage of blood supply at rest. The brain requires nearly 20% of the blood supply while only creating about 2% of the total human body weight in an average adult. 750 milliliters of blood flow into the brain every minute, regardless of whether or not the body’s movement has altered, slowed, or hastened. When this blood flow demand goes unmet, it is normal for the human brain to shut down and the body to lose consciousness. The brain is created by the most delicate and sensitive tissue in the body. The metabolic rate of the brain is not only oxygen hungry, but requires constant nutrients in order to function as well as an ample waste removal system. Toxins and drugs affect the brain very quickly and very significantly.
The high level of metabolic needs are in part serviced by the cerebral spinal fluid, which acts as the medium for nutrient and waste exchange between the blood and the brain and other nervous tissue. The cerebral spinal fluid also is responsible for maintaining an environment suitable for peaceful homeostasis within the brain and the central nervous system. The fluid is assisted by the neural tissue’s responsibilities of maintaining the blood brain barrier and giving off its secretions.
The circle of Willis is created by the unification of the paired internal carotid arteries and the vertebral arteries at the cerebral arterial circle. From each of the five basic regions of the brain stem basic functions and responsibilities.