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The control tower that governs all bodily functions is, of course, the brain. It is often said that IQ is determined by the proportion of the brain relative to body size. Whales, whose brain weighs around 5-8 kg, have a brain-to-body ratio of 1:2,000. Chimpanzees and orangutans, famous for their high IQ, have a ratio of about 1:100. The brain of human, often regarded as the pinnacle of creation, weighs about 1.5 kg and has a ratio of about 1:50. Perhaps due to its numerous functions, the brain weighs only 1.5 kg, yet it receives 20% of the blood volume from the heart. The brain, part of our body’s central nervous system, is connected to the spinal cord below and controls various body parts. The brain consists of approximately 100 billion nerve cells, or neurons, which constantly exchange information, not only regulating the functions of all organs, such as muscles, the heart, and the digestive system, but also governing complex mental activities, such as thinking, remembering, and imagining. Encased in a hard skull and multiple layers of meninges, the brain appears to float in a fluid called cerebrospinal fluid within the meninges. Looking closely at the brain, which weighs about 1.5 kg, it can be divided into the cerebrum, cerebellum, and brain stem based on its functions and structure. The largest part of the brain, the cerebrum, occupying three-quarters of the human brain, is composed of two hemispheres: the left and right. It is responsible for a wide range of functions, including sensation, perception, motor control, skill acquisition, creativity, reasoning, language ability, and insight. Additionally, it regulates the autonomic nervous system, controls hormone secretion, and maintains homeostasis. Located below and behind the cerebrum, the cerebellum is literally a tiny brain weighing about 150 g, accounting for 10% of the total brain mass and characterized by its fine surface folds. It keeps the body’s balance based on information received from the vestibular system. It also ensures that motor commands from the cerebral cortex are properly executed by selecting the appropriate muscles and determining the extent of their movement. Athletes are able to move faster and with greater precision than the average person, thanks to the development of their cerebellum, which advances alongside physical training. The brain stem, also known as the diencephalon, connects the cerebrum and the spinal cord and is responsible for unconscious life-sustaining functions such as breathing, digestion, and blood circulation. For this reason, it is often referred to as the ‘brain of life.’ The brain stem, located in the center of the brain and comprised of numerous nerve fibers, consists of the midbrain, pons, and medulla oblongata. The midbrain, located at the very center of the brain, helps maintain body balance and is involved in visual and auditory reflexes, such as eye movements and iris adjustments. The pons below the midbrain helps transmit information between the cerebellum and the cerebrum and governs facial and eye movements. The medulla oblongata, also known as the medulla, regulates breathing and circulation, and triggers unconscious activities like salivation, yawning, and sneezing to maintain the body’s condition. Given the brain's wide range of functions, brain damage can cause numerous diseases. Cerebrovascular damage, excessive alcohol consumption, smoking, and too much stress can lead to serious brain damage. Once destroyed, brain cells cannot be repaired. Therefore, living a healthy lifestyle is the key to maintaining a healthy brain. It is crucial to adhere to three key practices: a balanced diet, regular exercise, and a positive mindset. Conversely, it is advisable to avoid three risky behaviors: excessive alcohol consumption, smoking, and engaging in extreme sports.