Paper Topic:
The brain
The Brain Brain is the part of the nervous system that is enclosed in the skull All vertebrates (animals with backbones ) have well-developed brains most invertebrates (animals without backbones ) do not have true brains Instead , they have groups of nerve cells called nerve nets , nerve cords or ganglia . This article is concerned almost entirely with the human brain The human brain is an extension of the spinal cord , and with it makes u the central nervous system . It contains billions of neurons , or nerve cells , each with more than 10 ,000
synapses , or connections to other neurons . No two brain cells but it can bypass dead or damaged cells to form new synapses between existing cells (Corrick , 2003
The brain receives information from all parts of the body and sends out instructions to the body 's various organs and systems . The information and instructions travel through the brain in the form of nerve impulses electrical signals that elicit chemical changes . The impulses travel along the neurons and move from one neuron to the next across the synapses by means of chemicals called neurotransmitters . It is through nerve impulses that the brain controls such activities as voluntary and involuntary movement
The brain is connected with the sense organs , muscles of the head , and internal organs of the body by 12 pairs of cranial nerves , carry impulses from the brain to various parts of the body . Others , called sensory nerves , carry impulses from the body back to the brain . Most pairs of cranial nerves contain one motor and one sensory nerve a few pairs contain sensory nerves only
The brain consists of two types of tissue (1 ) nerve cells , or gray matter and (2 ) sheathed nerve fibers , or white matter . The sheath is composed of myelin , a fatty protein that protects and insulates the fibers (Kolb , 2005
A large number of blood vessels carry nourishment to the brain . The brain extracts certain substances from the blood and metabolizes them (that is , produces chemical changes in them ) to produce energy . Glucose its main source of energy , is metabolized by a chemical reaction with oxygen carried in the blood
The human brain is more complex and has more functions than the brain of any other animal . It is the seat of consciousness and the coordinator of the nervous system . Thought , memory , imagination , and other mental processes are functions of the brain . Specific areas in the brain are responsible for language and emotions . All voluntary and some reflex muscular movements are initiated and regulated by the brain . In addition , various parts of the brain control such automatic functions as heartbeat , temperature regulation , digestion , and breathing (Corrick 2003
The brain of the average human male weighs about 3 pounds (1 .4 kg the human female , 2 .7 pounds (1 .2 kg . At birth , a baby 's brain weighs only 11 to 13 ounces (310 to 370 g , but it grows rapidly during the first years of life . By the age of seven , a child 's brain...
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