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1. Maintaining a stable internal environment prevents dangerously wild swings in physiological conditions (such as temperatures, pH, salt levels, etc.).
2. A negative feedback loop always counteracts a stimulus to bring conditions back to a set point. Positive feedback, on the other hand, increases the stimulus in order to increase the response even further.
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4. The process of maintaining proper levels of water and solutes in the blood is referred to as osmoregulation. The millions of small nephrons in the kidneys are able to adjust the amount of water reabsorbed back into the bloodstream by changing the number of aquaporin proteins that line the collecting ducts. The chemical signal that leads to an increase in the numbers of these transport proteins is antidiuretic hormone (ADH).
5. When maintaining homeostatic levels of glucose in the bloodstream, the hormone insulin is responsible for lowering blood glucose levels. One way it removes free glucose from the bloodstream is by stimulating the liver to take in glucose and form the storage polymer, glycogen.
6. Uric acid is a solid, so when it is produced by the developing embryo that is stuck in the egg, it will form a solid precipitate (instead of toxifying the fluid environment).
7. The hypothalamus would increase ADH secretion, leading to an increased number of aquaporins embedded in the kidneys’ nephrons (this leads to more water being reabsorbed back into the bloodstream). The brain would also send signals of “thirsty!,” increasing water intake.
8. Land animals have kidneys that work more like marine fish because land animals are also battling water loss. The kidneys save water by reabsorbing it back into the bloodstream instead of allowing too much to be excreted in the urine.
9. d. Ocean fish are surrounded by a hypertonic (saltier) environment, compared to their tissue osmolarity. Salt will constantly move into their tissues by diffusion, and their body will lose water by osmosis. To battle this imbalance, a saltwater fish will conserve water and rid itself of salt by excreting concentrated, salty urine.