Scientific Literacy Essay – Burmese Python Intestinal Crypt Cells
Background Intestinal plasticity is an adaptation in animals that allows them to shut down their intestine in order to conserve energy. Only certain animals have this adaptation, and the adaptation is usually seen in animals that go long periods without eating, such as most snakes. Unlike mammals or birds that feed daily due to their fast metabolisms, snakes often fast for long periods of time. When they do eat, they often have to digest a food source that can be larger than half of their own body weight. To make their metabolism more efficient, snakes have developed intestinal plasticity which allows snakes to essentially turn off their intestine. For example, during fasting, the tissues in the intestine will shrink and the enzymes will also decrease, resulting in overall energy usage (Andrew, 2015). After feeding, the opposite occurs and there is a dramatic transformation. New cells are formed, digestive enzymes rise, and nutrient absorption increase. This rapid remodeling is what biologists call intestinal plasticity, and it allows snakes to be extremely efficient at maximizing their energy by only using it when necessary. This adaptation is often seen in sit-and-wait predators, such as the Burmese Python. Plasticity is a common theme in life, and is not limited to digestion. In vertebrates, maintaining proper levels of calcium and phosphorus in the body is equally important and requires precise hormonal control. Calcium, for instance, is essential for bone strength, but it is also critical for nerve impulses and muscle contractions. The parathyroid glands secrete parathyroid hormone (PTH) when calcium/phosphorous levels drop. PTH acts on bones, kidneys, and the intestine (through vitamin D activation) to bring calcium back into balance (Bringhurst et al., 2018). Inversely, calcitonin is a hormone produced by the thyroid gland that reduces blood calcium levels. When calcium levels rise too high, calcitonin helps by preventing bones from releasing calcium and encouraging calcium storage in bone tissue. In short, PTH increases blood calcium levels while calcitonin decreases blood calcium levels, and together they maintain homeostasis (Carter, 2006). For both intestinal plasticity and the homeostasis of elements such as calcium and phosphorous, biologists rely on advanced tools to visualize the microscopic cells involved. Electron microscopy is one tool, which works by shooting beams of electrons at a specimen, which allows biologists to achieve magnifications far beyond traditional microscopes (because electrons are smaller than wave of light used in light microscopes). Transmission electron microscopy (TEM) reveals the inner structure of cells, allowing biologists to see a detailed shape of the specimen. Another type is scanning electron microscopy (SEM), which provides sharp, three-dimensional image of the surface of a specimen. These methods have been invaluable to biology on their own, but in combination with new technologies, we have been able to learn even more about our world. For example, electron microscopy can be combined with Energy-Dispersive X-ray (EDX) analysis. EDX identifies which elements are...
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