Vitamin B-12 is a large molecule involved in many bodily processes, such as blood cell production and nervous system function. Your kidneys are involved in absorbing B-12 and other vitamins, which prevents them from escaping via urination.

Veins are close to the surface of the skin and carry deoxygenated blood from tissues back to the heart. Although most women try to prevent bulging veins, especially varicose veins caused by damage and inflammation, men usually welcome them, for aesthetic reasons.

The urinary system consists of the kidneys, bladder, the ureters that connect these structures; and the urethra, which carries urine from the bladder to the outside of the body. Diseases or abnormal conditions in other organ systems can disrupt normal urinary function.

Normally, the kidneys function as part of the excretory system and help the body filter waste out of the blood, which is then excreted as urine. The kidneys also help maintain a healthy blood pressure level within the body by removing excess salt and water from the blood.

Iodine is an essential mineral found in seafood, iodized salt and some fruits and vegetables. Excess iodine is normally removed from your body by your kidneys. However, if your kidneys are unhealthy, iodine may build up in your body, resulting in iodine toxicity.

Located on either side of your spine at the bottom of your ribcage, your kidneys are are bean-shaped organs that remove waste products from the blood. About the size of a fist, each kidney has about one million nephrons, tiny units inside the kidney where waste removal takes place.

When your body is in balance, it is said to be in homeostasis. If something becomes off, such as your blood pressure is too high or your body does not have enough fluid, your organs work to maintain balance.

The kidneys perform two vital functions for the body: regulating body fluids and excreting toxic wastes. The National Diabetes Information Clearinghouse notes that when the kidneys are healthy, they filter and clean the blood and send waste out of the body through urine.

Your kidneys filter your blood, and produce urine from extra fluid and waste products. The glomerular filtration rate (GFR), calculated using the creatinine blood test, is a measure of how well your kidneys filter your blood.

Your urinary tract consists of the kidneys, ureters, bladder and urethra. Urine is manufactured in the kidneys and drains down the ureters to the bladder, where it is stored temporarily. When you urinate, urine passes from the bladder through the urethra to the outside.

Although change in color of urine is normal, cloudiness can indicate that something is wrong. It's good to know when to see a doctor.

Fruit nourishes you with fiber, minerals and vitamins, but some can be better than others for keeping your kidneys healthy. In general, look for fruit that's rich in antioxidants -- such as flavonoids and vitamins A, C and E -- and low in potassium.