Urea, together with water and other waste substances, forms the urine as it passes through the nephrons and down the renal tubules of the kidney. From the kidneys, urine travels down two thin tubes called ureters to the bladder. The ureters are about 8 to 10 inches long. Muscles in the ureter walls constantly tighten and relax to force urine downward away from the kidneys. If urine is allowed to stand still, or back up, a kidney infection can develop.
SAGITTARIUS (November 23-December 21) LUCKY DAY: Thursday THE per fect woman for a Sagittarian man is a Gemini - which is why Brad Pitt and Angelina Jolie are Hollywood's golden couple. Celebs with stars in their (sex) lives; New PEOPLE astrologer Claire Petulengro takes a look at what 2009 holds for some of the biggest names
Pi Day is an annual celebration of the mathematical constant Ï. Pi Day is observed on March 14 since 3, 1, and 4 are the first three significant digits of Ï. In 2009, the United States House of Representatives supported the designation of Pi Day. Pi Approximation Day is observed on July 22, since the fraction 22â7 is a common approximation of Ï, which is accurate to two decimal places and dates from Archimedes.