Aging Changes In The Urinary System
Normal changes occur in the urinary system as a person gets older.
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The job of the urinary system is to get rid of waste and extra fluid in the body by filtering the blood and excreting the wastes as urine. Important substances can be returned to the blood after it is filtered.
Taking the parts of the urinary system in the order of their function, the kidneys come first. Next are the ureters, tubes that carry urine from each kidney to the bladder. The bladder holds the urine until the person is ready to urinate. The urethra is a narrow tube that allows urine to pass from the bladder out of the body. In the female, the urethra is short, travels within the pelvis and opens to the the outside just anterior to the vagina. In the male, the urethra travels the length of the penis and opens at its tip.
Every part of this system can be affected by aging. Each kidney is made up of millions of filtering units called nephrons. At birth, babies have extra nephrons. However, the number and size of nephrons slowly decreases with age. When this number dips below a certain point, the kidneys start to lose function. This means waste and extra fluid are not filtered out of the body as efficiently in older people.
The kidneys gradually become smaller with age, partly due to the loss of nephrons. Blood flow to the kidneys is also reduced. The rate at which blood is sent through to the kidney can be diminished if the blood vessels lose their elasticity, or become stiffer. They can also be narrowed through plaque buildup, similar to what happens in the coronary arteries. This also impairs the filtering process.
Another function of the kidneys is to balance the amount of salt and acid in the body. This function also declines with age, making it harder for the body to correct salt and acid imbalance problems. The production and efficiency of hormones that tell the body it is becoming dehydrated decreases with age. This poses a risk for dehydration.
Bladder tissue becomes much less elastic (stretchable) with age. This decreases the amount of urine the bladder can hold. The muscles of the bladder also become weaker. This makes the bladder unable to squeeze hard enough to get rid of all the urine it contains. This means that more urine is left in the bladder after a person urinates. These two changes may cause an older person to have to urinate more often.
The sensation of needing to urinate is often delayed in older people. Normally, when the bladder gets to be nearly full, a person starts to feel an urge to urinate. In older people, this urge may be delayed. When an older person finally feels the need to urinate, the need may be sudden.
Changes in the reproductive system also affect how the urinary system functions. The pelvic floor muscles normally get weakened with age, especially in women. Childbirth contributes to this weakness. In fact, these pelvic muscles sometimes grow so weak that the bladder and urethra prolapse, or fall into the vagina. The end result is that older women may become incontinent, or lose urine involuntarily.
The normal delay in feeling the urge to urinate adds to this problem to make incontinence quite common in the elderly. Urine flow can also be blocked by an enlarged prostate gland in men. This condition is called benign prostatic hyperplasia (BPH), and is common in aging men. The prostate lies just under the bladder and surrounds part of the urethra.
BPH may cause difficulty starting the urine stream, a weak urine stream, and dribbling of urine. An enlarged prostate also causes incomplete voiding of urine from the bladder. As a person ages, he or she is at higher risk for urinary tract infections, acute renal failure, and chronic renal failure.
Factors that contribute to the increased risk include:
Many other problems with the urinary system are more common with age but are not considered normal changes. Cancer, high blood pressure, diabetes, heart disease and other conditions can all lead to urinary system problems. In order to rule out these conditions, the individual should consult with the healthcare professional.