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I Introduction

The ability for humans to live and breathe is controlled by various organs and processes in the body. No matter what they do, each organ plays a part in the human body and ultimately the human life, also known as homeostasis. But of all the different forms of homeostasis, from body temperature to the ability to walk, the one to be studied in this experiment is that of the excretory system, more specifically the kidneys.
It is basic knowledge that when liquids are ingested into the human body, the majority of the waste resulting from it is excreted by urine. When more of a liquid is ingested, it appears that more urine is released, whereas if one is dehydrated, less is excreted. Certainly, this exhibits the body’s ability to control the amount of urine being released from the body, based on its conditions. But how? Urine excretion is controlled by the kidneys. The kidneys, part of the urinary system in the human body, are located in the posterior part of the abdomen. There is one on each side of the spine; the right sits just below the liver, the left below the diaphragm and next to the spleen. Their job is to filter wastes from the blood, in this project specifically urine, and release them to the bladder, where they are then released from the urethra, a tube that collects the urine from the bladder. However, none of this can happen without liquids to excrete.
When simple water is ingested into the human body, there is usually a rapid excretion of it through the urinary tract. However, upon the ingestion of various forms of saline, basically salt and water, the urine is excreted less expediently, due to the effects of the saline on the kidneys, basically absorbing multitudes of the liquid to be released at a further time. Moreover, when caffeine, a human stimulant compound, is ingested, it appears that urine excretion is far more rapid than that of both saline and tap water ingestion.
Also varying between theses two groups, it is possible that not only does the amount of urine vary between different liquid consumption, but also varies by way of urine pH and coloration. Under normal conditions, the pH of urine is slightly acidic, because metabolic reactions in the cells generate acid materials. The normal pH of urine is about 6; although, under certain conditions, the pH could be as low as 4.5 or as high as 8. The color of urine is due to the presence of bile pigments which are end products of hemoglobin metabolism. If these pigments are concentrated in urine, then urine would have a darker color. If these pigments are not as concentrated, the urine will appear almost colorless.
This poses the question, “Can the kidneys alter the output of urine in response to different liquid ingestions?” Three liquids will be used in this experiment, each of which represents a different property. Hopefully they can affect the kidneys in ways enough to give evidence that they can alter urine. They are:
-Tap water
-Gatorade (which includes isotonic saline, a form of salt)
-Mountain Dew (a soft drink high in caffeine)



The null hypothesis is that the kidneys can not alter the urine outside of chance. However, the alternative hypotheses are:
• Hypothesis A: The Kidneys do have the ability to alter urine outside of chance
If hypothesis A proves true:
• Caffeine will cause the kidney to excrete the most urine out of all the tested liquids
• Isotonic saline will cause the kidney to excrete the least urine out of all the tested liquids.

yeahh, i agree with mooby on the 'hopefully' part.

also, this sentence:
"Their job is to filter wastes from the blood, in this project specifically urine, and release them to the bladder,..."
i might be being nitpicky here, but kidneys don't filter urine from the blood, they filter different substances that combine to turn into urine as they leave the kidneys. n__n;

i think that's how it works, anyways, if i remember correctly from fall semester. x____x;