Chapter 45 Lecture Enrichment Ideas
Describe the role of the excretory system in excretion and why it is so important that nitrogenous wastes be removed from the body; only the American bear can recycle amino acid metabolic wastes to usable proteins during hibernation; all other organisms must rid themselves of these toxins.
A freshwater fish placed in the ocean, or a marine fish placed in fresh water are under terrific physiological stress.
A contrast of these two systems helps emphasize the modifications found in organisms.
Review the countercurrent mechanism in fish gill oxygenation as a review of the same concept found in the human kidney.
There is an overall principle in excretory systems of pushing out most fluids and then reabsorbing the useful nutrients and water; this can be a running theme as flame cells, Malpighian tubules, and nephrons are described.
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