C+-+How+do+kidney+stones+form?


 * How do kidney stones form (Hao Lin)**

Kidney stones are hard, solid particles that form in the urinary tract. The formation of kidney stones are related to the formation of urine. The process of urination begins in the kidneys. The kidneys filter out fluids and waste from the body, producing urine. As the urine passes through the kidneys, it becomes more concentrated. From the kidneys, urine flows from through thin tubes called //ureters// into the bladder. The bladder's stretchy walls expand to store the incoming urine until it leaves the body through a tube called the urethra.
 * Introduction to the topic**

Occasionally, various salts build up on the inside surfaces of the kidney and form crystals. Eventually these crystals become large enough to form stones in the kidney. Kidney stones may also form in the ureter or the bladder. Combination of minerals and other chemicals, some derived from a person's diet, make up the salts in these stones.

1) A high concentration of stone-forming mineral salts in the urine. When high levels of stone-forming substances such as calcium oxalate, calcium phosphate, or struvite are present in the urine, one or more crystals may form and become trapped within the urinary tract. The crystal may attract other crystals and bind together with them, growing into a stone. 2) An uneven balance of acid in the urine. The acidity or alkalinity of the urine affects the ability of stone-forming substances to remain dissolved. Some types of stones will form in acidic urine; others will form only in alkaline urine.
 * 3 common ways of kidney stone formation**

3) A lack of substances in the urine that prevent the growth of crystals. Normally, substances that inhibit the formation and growth of crystals - such as pyrophosphates, citrate, and magnesium - are present in the urine. A decrease in or absence of these substances may cause a stone to develop.

1) Calcium stones, the most common kind, are formed because certain foods upset the balance of acid in the urine. Cancer patients are more likely to form calcium stones because cancer can cause the body to produce an abnormally large amount of parathyroid hormone, which regulates calcium levels in the body. High levels of this hormone can break down bone and releases too much calcium into the blood. As a result, calcium saturates the urine.
 * 4 kinds of kidney stones and their specific requirements of formation**

2) // Uric stones, about 10% of kidney stones, are formed because of high concentration of uric acid in the urine. //

3) Cystine stones can form from high amounts of cystine in the urine, the result of a rare in inherited abnormality.

4) Struvite stones may form in the kidney or bladder as a result of infection from certain bacteria.


 * Work Cited**

How Do Kidney Stones Form?. (n.d.). //eHealthMD//. Retrieved January 4, 2011, from http://www.ehealthmd.com/library/kidneystones /ks_form.html

Sherwood, C. (n.d.). How Are Kidney Stones Formed? . //eHow//. Retrieved January 4, 2011, from http://www.ehow.com/how-does_5118033_kidney-stones-formed.htm

Kidney Stones - Symptoms, Treatment and Prevention. (n.d.). //Consumer Health News, Information and Resources Updated Daily//. Retrieved January 4, 2011, from http://www.healthscout.com/ency/68/137/main.html

Kidney stones. (n.d.). //National Library of Medicine - National Institutes of Health//. Retrieved January 4, 2011, from http://www.nlm.nih.gov/medlineplus/ency/article/000458.htm