Sensory Reception, Human

human sensory reception, means by which humans react to changes in external and internal environments.

cross section of the human eye

Ancient philosophers called the human senses “the windows of the soul,” and Aristotle described at least five senses—sight, hearing, smell, taste, and touch. Aristotle’s influence has been so enduring that many people still speak of the five senses as if there were no others. Yet the modern sensory catalog now includes receptors in the muscles, tendons, and joints, which give rise to the kinesthetic sense (that is, the sense of motion), and receptors in the vestibular organs in the inner ear, which give rise to the sense of balance. Within the circulatory system, sensory receptors are found that are sensitive to carbon dioxide in the blood or to changes in blood pressure or heart rate, and there are receptors in the digestive tract that appear to mediate such experiences as hunger and thirst. Some brain cells may also participate as hunger receptors. This is especially true of cells in the lower parts of the brain (such as the hypothalamus) where some cells have been found to be sensitive to changes in blood chemistry (water and other products of digestion) and even to changes in temperature within the brain itself.