Every organ in the body performs specific duties. Each organ functions as a member of a community of organs, all contributing to the good of the body as a whole. The brain, the "high commander," dictates the functions of most organs. The heart pumps blood (at varying rates and pressures, depending on the brain's signals) to other tissues and organs, the lungs breathe air (providing necessary oxygen to tissues and organs via the bloodstream), and the stomach digests food (providing nutrients to itself and other organs and tissues in the body). The pancreas and gallbladder assist with that digestion, while the liver and kidneys help to process and excrete toxins from the body. The reproductive organs (ovaries in a woman and testes in a man) ensure that the elements that define the individuality of a person (the genes) get passed on to the next generation. Every organ is composed of tissues; tissues are, in turn, composed of cells.
The human body has evolved with a complicated set of organs, each of which performs specific functions and each of which relies on and communicates with other organs for the good of the whole individual. The brain, for example, controls higher-order functioning (memory, thought, sensory input and output) and basic bodily functions (breathing, the beating of the heart, the drive to eat and sleep). It transmits electrical signals to the heart to beat faster or slower, to the movement. It also sends out hormonal signals through the release of chemicals from the pituitary gland. These signals affect other organs, including the heart, lungs, kidneys, reproductive organs, and thyroid gland. The organs affected by the brain then vary their function, in turn sending out signals (either electrical, chemical, or both) to still other organs, then back to the brain to provide "feedback" about how the organ is responding to the brain's initial stimulus.
A scenario may clarify these interactions. You are walking in the forest one day when a tiger jumps out from the bushes. Your brain thinks, "Oh my God, it's a tiger! I'm in trouble!" - a process known as "higher-order functioning." It then transmits electrical signals to the heart to beat faster, to the lungs to breathe harder (basic bodily functions), and to the muscles to tense up, preparing you to flee from or to fight the tiger (your choice!). At the same time, the brain triggers to the pituitary gland (also located in the skull) to release hormones, including one that stimulates the adrenal glands to produce adrenaline (epinephrine). Adrenaline also in turn, send signals back to the brain to tell it "Okay - we're really moving now! You can stop signaling us to work harder. We're already doing it!" (feedback). These organs work together to ensure survival.
Organs, then, perform specific functions, but they also respond to both electrical and chemical stimuli from other organs, all for the good of the individual.
The human body has evolved with a complicated set of organs, each of which performs specific functions and each of which relies on and communicates with other organs for the good of the whole individual. The brain, for example, controls higher-order functioning (memory, thought, sensory input and output) and basic bodily functions (breathing, the beating of the heart, the drive to eat and sleep). It transmits electrical signals to the heart to beat faster or slower, to the movement. It also sends out hormonal signals through the release of chemicals from the pituitary gland. These signals affect other organs, including the heart, lungs, kidneys, reproductive organs, and thyroid gland. The organs affected by the brain then vary their function, in turn sending out signals (either electrical, chemical, or both) to still other organs, then back to the brain to provide "feedback" about how the organ is responding to the brain's initial stimulus.
A scenario may clarify these interactions. You are walking in the forest one day when a tiger jumps out from the bushes. Your brain thinks, "Oh my God, it's a tiger! I'm in trouble!" - a process known as "higher-order functioning." It then transmits electrical signals to the heart to beat faster, to the lungs to breathe harder (basic bodily functions), and to the muscles to tense up, preparing you to flee from or to fight the tiger (your choice!). At the same time, the brain triggers to the pituitary gland (also located in the skull) to release hormones, including one that stimulates the adrenal glands to produce adrenaline (epinephrine). Adrenaline also in turn, send signals back to the brain to tell it "Okay - we're really moving now! You can stop signaling us to work harder. We're already doing it!" (feedback). These organs work together to ensure survival.
Organs, then, perform specific functions, but they also respond to both electrical and chemical stimuli from other organs, all for the good of the individual.
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