Lesson 1, Topic 1
In Progress

Life Span Changes of the Urinary System

April 11, 2024

Learning Objective: Analyze the life span changes to the urinary system.
      At about 10 to 12 weeks after conception, the kidneys start producing urine. While the baby is in utero, the mother’s placenta performs most of the kidneys’ function until the last few weeks before birth. When babies are born, they have the same number of nephrons as adults. The nephrons are immature and reach maturity by age 2. A baby’s kidneys do not retain water like adult kidneys do. Thus, babies can lose water quickly, especially when they are hot or if they have diarrhea. During childhood, the bladder continues to grow. Bladder control is usually learned between ages 2 and 3.
      During the adult years, males are more likely to develop kidney stones. This may be attributed to the amount of food they eat. They need to drink more water than females to clear the waste products from the body. Male kidneys also have an increased ability to concentrate urine, a risk factor for kidney stones. Females are at more risk for urinary tract infections (UTIs) than males. This is attributed to the anatomic differences. Most UTIs are caused by Escherichia coli, which is found near the vagina and rectum. The closeness of the urethra to these structures and the shortness of the urethra increase the risk of UTIs.

Changes with Pregnancy
Learning Objective: Describe changes to the urinary system during pregnancy.
      During pregnancy, the filtration rate increases in females. The number of nephrons remains the same, but the filtration surface increases. This increase allows the kidneys to filter more blood, which is useful with the increased blood flow during pregnancy. In late pregnancy, the bladder may be twice as big. The anatomic and physiologic changes that occur during pregnancy put women at more risk for pyelonephritis at that time.

Changes in Older Adults
Learning Objective: Describe changes to the urinary system that occur with aging.
      In older adults, the kidney tissue and number of nephrons are reduced by up to 20%. The renal arteries can harden. This causes the kidneys to filter blood slower. The kidneys become less able to regulate water balance. Older adults are at more risk of dehydration when the weather is hot or if they have diarrhea. The bladder wall becomes less stretchy with age. The bladder cannot hold as much urine as before. Bladder muscles weaken. The urethra may be obstructed by an enlarged prostate gland or a prolapse of the bladder or vagina. Older adults are at more risk for chronic kidney disease, UTIs, and incontinence.