Excretion Is Not EliminationThe excretory system is very important to your body and only has a few parts. In a similar way to removing solid waste from your body, you must also get rid of fluids. You know the results of the excretory system as urine.
Urine is the result of the excretory system balancing the amount of water and salts in your body. We said the system is small. Your kidneys are the core organs involved in the excretory system. Related body parts include the ureters, bladder, and urethra. Once the urine passes through your urethra, that's it, it's out of your body.
What Does This System Do?What do those kidneys do? The regulation process of body fluids and salt levels is also called osmoregulation. The kidneys act as a filter. Eventually all of the blood in your body passes through the kidneys and they are able to do their filtering magic. The kidneys pull harmful molecules out of your bloodstream and leave the ones that are good for you.
The kidneys are also key players in the hydration (water) levels for your body. Let's say you are in the desert and you haven't been drinking much water. Chemical signals are sent to your kidneys to reabsorb as much water as possible. The result is less urine creation and your body loses less water. A normal day has you creating about one and a half liters of fluid.
Interacting with Other SystemsThe excretory system is a close partner with both the circulatory and endocrine system. The circulatory system connection is obvious. Blood that circulates through the body passes through one of the two kidneys. Urea, uric acid, and water are removed from the blood and most of the water is put back into the system.
The endocrine system is the major controller of the excretory system. As levels of compounds and fluids are monitored, kidney function must be constantly altered to provide the best internal environment for your cells. If you drink too much water, hormones are released that allow for more urine production. If you are dehydrated, less urine will be produced. The kidneys are also tied to the endocrine system with the adrenal gland position on the top of each kidney. The adrenals release adrenaline into your body.
Nasty DiseasesWhile there are many diseases of the excretory system, even more problems can be created by a malfunctioning set of kidneys. Blood pressure is closely tied to the amount of fluid in your body. If a kidney does not work and filter properly, blood pressure can increase to dangerous levels. If that weren't bad enough, urea would accumulate in your tissues and would slowly poison the cells of your body.
People with malfunctioning kidneys often have to go through a process called dialysis where they are hooked up to a machine that filters their blood. The machine acts as an artificial kidney and tries to re-establish normal levels of ions and water in their bodies. Many people on dialysis are waiting for kidney transplants.
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Useful Reference MaterialsEncyclopedia.com:
Books on Amazon.com:
- Modern Biology (Rinehart and Holt)
- Campbell Biology: Concepts and Connections (Reese, Taylor, Simon, and Dickey)
- Prentice Hall: Biology (Miller and Levine)
- Principles of Human Physiology (Silverthorn)
- Principles of Human Physiology (Stanfield)
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