The three main systems of government used today are unitary systems, federal systems, and confederate systems
The brain represents 2% of the total body weight for a human. But it uses 20% of the total oxygen and calories absorbed by the body (so ten times more than its weight ratio) it proves that it is an important organ that need a lot of energy.
The brain is the seat of higher functions (cognitive functions, senses, nervous responses) and vegetative functions. It is, therefore, an essential organ that regulates all vital functions. Like a central unit in a desk computer, the brain receives information from the entire human body via afferent nerves, integrates and analyzes them, and responds by emitting new signals that descend to the parts of the body concerned by the efferent nerves.
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Phagocytosis is a critical part of the immune system. ... By knowing the enemy, the cells of the immune system can specifically target similar particles circulating in the body. Another function of phagocytosis in the immune system is to ingest and destroy pathogens (like viruses and bacteria) and infected cells.
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