Explain excretion from Morden biology text book
Excretion is the biological process through which waste products and harmful substances are removed from an organism's body. It is an important process for maintaining homeostasis and overall health. In the field of biology, the process of excretion is typically studied in relation to humans, but it also occurs in many other organisms.
The textbook may start by explaining the main organs and systems involved in excretion. The urinary system, consisting of the kidneys, ureters, bladder, and urethra, is primarily responsible for excreting metabolic waste products in humans. The kidneys filter waste products, excess ions, and water from the blood to produce urine. This urine then passes through the ureters and is stored in the bladder until it is eliminated from the body through the urethra.
Additionally, the textbook may mention other excretory organs and systems in animals. For example, in fish, excretion mainly occurs through the gills, where waste substances are eliminated along with the water that enters during respiration. In insects, excretion occurs through specialized structures called Malpighian tubules, which remove waste products from the hemolymph (insect blood) and excrete them as solid waste.
Furthermore, the text may explain the different waste products excreted by organisms. In humans, the main waste product is urea, which is produced when the liver breaks down excess amino acids. Other waste products excreted through urine include excess water, ions, and metabolic byproducts such as creatinine.
The mechanisms of excretion, such as filtration, reabsorption, and secretion, would likely be discussed as well. Filtration occurs in the kidneys, where blood pressure forces water, ions, and small molecules to pass through the glomerulus and enter the renal tubules. Reabsorption then takes place, where essential substances such as glucose, amino acids, and water are reabsorbed back into the bloodstream. Meanwhile, unwanted substances such as toxins, excess ions, and waste products are secreted into the renal tubules. Finally, urine is formed and transported out of the body.
Lastly, the textbook may touch upon the importance of excretion for maintaining proper bodily functions. It emphasizes that the removal of waste products prevents the buildup of toxic substances, which can be detrimental to an organism's health. By excreting waste, organisms regulate the balance of water, ions, and other essential substances in their bodies. Overall, excretion is a vital process that ensures the proper functioning and survival of living organisms.