The major organs of the urinary system are the kidneys and the bladder, attached to each other and the outside of the body by tubes. Strictly speaking, however, the process of urination, the removal of wastes from the body, begins at cellular level. As all cells function, converting food into energy and repairing body tissue, they produce wastes which must be flushed out of the body. These wastes are secreted into the blood stream and carried to the kidneys where they are separated from the blood once more, ready for excretion. The two kidneys, situated in the lower part of the back, and protected by a layer of fat, contain hundred of kilometres of minute tubes called nephrons. Visible only under a microscope, the nephrons each contain a network of tiny capillaries where the exchange of fluid from the blood to the urinary system takes place. As the blood flows into the kidneys through the renal artery and through the capillaries in the nephrons, the fluid is temporarily separated from the solid blood components such as red and white blood cells. The blood cells remain inside the capillary walls. Once the fluid has passed down the stem of the nephron, most of it, containing the body’s requirements of water, amino acids, glucose, minerals and proteins is returned to the circulating blood. The remaining substances like excess water, salt, urea and uric acid are excreted from the kidneys as urine. The urine travels from each kidney down tubes called the ureters to the bladder. Just as it feels when full, the bladder is a bag-like organ which expands to collect and store the urine trickling down from the kidneys. When about 200-300mls of urine has collected in the bladder, pressure receptors in the bladder wall send messages to the brain, conveying the desire to urinate. In a toilet trained human, the brain can control the relaxing of the sphincter, the muscle which holds the bladder shut. When the sphincter is relaxed, a series of muscle contractions in the diaphragm and abdomen help the bladder empty itself. The urine passes out of the body via another tube called the urethra.

It’s easy to see, therefore, how common infections of the urethra and bladder, known respectively as urethritis and cystitis, can easily spread via the ureters into the kidneys. Known as pyelonephritis, this bacterial kidney infection causes pain in the lower back and sides and fever, as well as the symptoms of cystitis: a raging thirst, the frequent need to urinate and burning pain during urination. Tests of the urine may show up blood cells and pus.

Quite different, rarer and much more serious, is the kidney disease known as nephritis. This occurs when the antibodies in the bloodstream attack the tissue of the kidneys. Symptoms include limited amounts of red, brown or cloudy-brown urine, water retention, headache, backache and high blood pressure. If not seen to by a qualified medical practitioner immediately, nephritis can lead to kidney failure.

Kidney stones result when urine is too highly concentrated. Uric acid or calcium suddenly falls out of solution and crystallises into small stones in either the kidneys or the ureters. Short, sharp pains in the back and abdomen result. The patient should cut down on their intake of calcium and those in hard water areas may even need to drink filtered water to lower the mineral levels in their blood. A naturopath will probably prescribe tonics containing gentle diuretic herbs like dandelion and bearberry (uva ursi).

For general good kidney health make sure you drink plenty of fresh water daily. Dehydration in hot weather concentrates the urine and makes the development of stones and infections much more likely. Empty your bladder regularly and cut down tea, coffee and alchol.

Difficulty or strain when urinating can occur in men when the prostate is enlarged.


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