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Ch. 15 The Urinary System
Marieb - Essentials of Human Anatomy & Physiology 13th Edition
Marieb13th EditionEssentials of Human Anatomy & PhysiologyISBN: 9780135624340Not the one you use?Change textbook
Chapter 15, Problem 24

Describe the changes that occur in kidney and bladder function in old age.

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1
Understand the anatomy and physiology of the kidney and bladder: The kidneys are responsible for filtering blood, removing waste, and regulating fluid and electrolyte balance. The bladder stores urine until it is excreted. Both organs are part of the urinary system, which undergoes changes with aging.
Identify the structural changes in the kidneys with aging: The kidneys tend to decrease in size and weight due to a reduction in the number of functional nephrons (the filtering units of the kidney). This can lead to a reduced glomerular filtration rate (GFR), which affects the kidney's ability to filter blood efficiently.
Examine the functional changes in the kidneys: Aging kidneys may have a diminished ability to concentrate urine and regulate electrolyte balance. This can result in increased susceptibility to dehydration and imbalances in sodium and potassium levels.
Explore the changes in bladder function: The bladder's capacity to store urine may decrease with age, and the detrusor muscle (responsible for bladder contraction) may weaken. This can lead to increased urinary frequency, urgency, and a higher risk of urinary incontinence.
Consider the impact of age-related changes on overall health: Reduced kidney function and changes in bladder control can increase the risk of urinary tract infections (UTIs), kidney disease, and other complications. Understanding these changes is important for managing urinary health in older adults.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Renal Function Decline

As individuals age, renal function typically declines due to a decrease in the number of functioning nephrons and reduced renal blood flow. This decline can lead to decreased glomerular filtration rate (GFR), which affects the kidneys' ability to filter waste and maintain fluid and electrolyte balance.
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Bladder Capacity and Compliance

With aging, the bladder's capacity and compliance often decrease, leading to increased frequency of urination and a higher risk of incontinence. The detrusor muscle may become less efficient, resulting in incomplete bladder emptying and increased residual urine volume.
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Hormonal Changes

Aging is associated with hormonal changes that can impact kidney and bladder function. For instance, decreased levels of antidiuretic hormone (ADH) can affect water retention, while changes in sex hormones can influence bladder control and urinary tract health, contributing to common issues such as nocturia and urgency.
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