Kidney Function Overview
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Questions and Answers

What percentage of glucose is reabsorbed in the proximal convoluted tubule (PCT)?

  • 65%
  • 90%
  • 100% (correct)
  • 25%

Which substance is primarily secreted into the tubule at the proximal convoluted tubule (PCT)?

  • Glucose
  • Uric acid (correct)
  • Sodium
  • Bicarbonate

At which part of the nephron is approximately 25% of water and sodium chloride reabsorbed?

  • Distal convoluted tubule
  • Loop of Henle (correct)
  • Collecting tubule
  • Proximal convoluted tubule

What happens at the distal convoluted tubule (DCT)?

<p>Potassium and hydrogen are secreted (A)</p> Signup and view all the answers

What is the specific gravity of glomerular filtrate?

<p>1.010 (D)</p> Signup and view all the answers

What is a characteristic of an ideal marker for measuring GFR?

<p>Must be freely filtered at the glomerulus (B)</p> Signup and view all the answers

Which of the following substances behaves similarly to creatinine regarding kidney filtration?

<p>Inulin (A)</p> Signup and view all the answers

Which substance does not appear in the urine until its plasma level reaches about 180 mg/100ml?

<p>Glucose (C)</p> Signup and view all the answers

What is the first function to decrease in tubular damage?

<p>Concentrating ability (C)</p> Signup and view all the answers

Which condition is NOT associated with impairment of tubular cells' concentrating ability?

<p>Hypotension (D)</p> Signup and view all the answers

What specific gravity value indicates severe tubular function impairment?

<p>Below 1.020 (A)</p> Signup and view all the answers

Which factor does NOT limit the usefulness of dilution tests?

<p>Renal blood flow (A)</p> Signup and view all the answers

What is the standard specific gravity for at least one urine specimen in a dilution test?

<p>Less than 1.003 (D)</p> Signup and view all the answers

Why is specific gravity measurement more commonly performed than osmolality measurement?

<p>It is easier and quicker (A)</p> Signup and view all the answers

What does specific gravity measure in urine?

<p>The concentration of chemical particles (D)</p> Signup and view all the answers

Which of the following is true regarding the diluting ability of the kidneys?

<p>It is tested over 3 to 4 hours (C)</p> Signup and view all the answers

What is the primary role of erythropoietin (EPO) produced by healthy kidneys?

<p>To stimulate production of red blood cells (D)</p> Signup and view all the answers

How do kidneys contribute to toxin removal from the body?

<p>By using glomeruli to separate wastes from blood (D)</p> Signup and view all the answers

Which hormones are primarily involved in blood pressure control by the kidneys?

<p>Renin and angiotensin (C)</p> Signup and view all the answers

What role do the kidneys play in maintaining electrolyte balance?

<p>They filter electrolytes and adjust excretion as needed (B)</p> Signup and view all the answers

What does the urine specific gravity (sp.gr.) primarily measure?

<p>Concentrating ability of renal tubules (C)</p> Signup and view all the answers

Which of the following describes the role of calcitriol produced by the kidneys?

<p>It keeps bones strong (B)</p> Signup and view all the answers

Which condition is characterized by an elevation in urine specific gravity in the absence of dehydration?

<p>Uncontrolled diabetes with glycosuria (D)</p> Signup and view all the answers

What happens when healthy kidneys produce insufficient erythropoietin?

<p>Development of anemia (C)</p> Signup and view all the answers

What is observed in patients who have undergone diagnostic studies using iodine-containing x-ray contrast media?

<p>Extremely high urine specific gravity (A)</p> Signup and view all the answers

How do the kidneys respond to fluctuations in water and electrolyte levels?

<p>By adjusting based on antidiuretic hormone (ADH) and aldosterone (D)</p> Signup and view all the answers

Which solute components contribute most to serum osmotic concentration?

<p>Sodium, chloride, bicarbonate ions (A)</p> Signup and view all the answers

Which process allows the kidneys to filter about 190 liters of blood daily?

<p>Glomerular filtration (A)</p> Signup and view all the answers

What is the purpose of simultaneously measuring serum and urine osmolality?

<p>To assess kidney function and concentrating ability (D)</p> Signup and view all the answers

Which factor greatly affects the ratio of urine osmolality to serum osmolality?

<p>Fluid intake volume (D)</p> Signup and view all the answers

What does osmotic clearance measure?

<p>Concentration of osmotically active particles in urine relative to serum (C)</p> Signup and view all the answers

Which of the following does not get excreted by the kidneys in its free form?

<p>Strong acids like sulfuric and hydrochloric (D)</p> Signup and view all the answers

What is a primary consequence of diminished kidney function due to inadequate blood flow?

<p>Accumulation of metabolic products in the blood (B)</p> Signup and view all the answers

What is renal hypertension?

<p>An increase in blood pressure due to inadequate renal blood flow (A)</p> Signup and view all the answers

Which of the following best describes why glomerulonephritis affects kidney function?

<p>It damages the capillary epithelium in the kidneys (C)</p> Signup and view all the answers

What could result from a massive hemolytic reaction after receiving incompatible blood?

<p>Toxic effects on the tubular function (B)</p> Signup and view all the answers

What is a common result in nephrotic syndrome related to kidney function?

<p>Loss of large amounts of proteins in the urine (D)</p> Signup and view all the answers

Which of the following factors could negatively impact normal kidney function?

<p>Mechanical trauma to the kidney (A)</p> Signup and view all the answers

The accumulation of red blood cells in urine during glomerulonephritis is primarily due to which issue?

<p>Damage to the glomerular membrane (B)</p> Signup and view all the answers

What type of kidney dysfunction is not associated with intrinsic lesions in the kidney?

<p>Diminished kidney function from cardiac failure (B)</p> Signup and view all the answers

What is the primary mechanism by which post-renal causes decrease renal function?

<p>By reducing the effective filtration pressure of the glomeruli (C)</p> Signup and view all the answers

Which of the following is a common pre-renal cause of decreased kidney function?

<p>Dehydration (A)</p> Signup and view all the answers

Which laboratory test is most commonly used to evaluate kidney function?

<p>Glomerular filtration rate (GFR) (C)</p> Signup and view all the answers

What condition might cause increased urine albumin or protein levels without intrinsic renal pathology?

<p>Posture changes (D)</p> Signup and view all the answers

What does the presence of albumin in urine indicate?

<p>Abnormal kidney function (D)</p> Signup and view all the answers

Which of the following can be a post-renal cause of decreased kidney function?

<p>Prostatic enlargement (D)</p> Signup and view all the answers

Which of the following correctly identifies an intra-renal cause of decreased kidney function?

<p>Aminoglycosides (C)</p> Signup and view all the answers

What impact does an obstruction from kidney stones have on kidney function?

<p>Reduces effective filtration pressure of the glomeruli (D)</p> Signup and view all the answers

Flashcards

What is EPO and what does it do?

Erythropoietin (EPO) is a hormone produced by the kidneys that stimulates the bone marrow to produce red blood cells. Red blood cells carry oxygen throughout the body.

What is the role of the kidneys in waste removal?

The kidneys filter waste products and excess water from the blood. These substances are then excreted as urine.

How do kidneys regulate blood pressure?

The kidneys produce hormones like renin and angiotensin, which regulate sodium (salt) and fluid balance in the body. They also control blood vessel dilation and constriction, contributing to blood pressure regulation.

How do kidneys maintain electrolyte balance?

The kidneys filter electrolytes from blood, return some to the blood, and excrete excess electrolytes in urine. This helps maintain a balance between intake and excretion.

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What is the role of the kidneys in bone health?

The kidneys produce calcitriol, a hormone essential for bone health. Calcitriol helps regulate calcium levels in the body.

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Renal Filtration

The process of removing waste products, excess water, and electrolytes from the blood, forming urine.

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Proximal Convoluted Tubule (PCT)

The section of the nephron where the majority of the glomerular filtrate is reabsorbed back into the blood.

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Threshold Substances

Substances that are fully reabsorbed from the glomerular filtrate in the PCT.

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Example of Threshold Substances

Substances that appear in the urine only when their concentration in the blood exceeds a specific level.

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Loop of Henle

The section of the nephron responsible for concentrating urine by reabsorbing water and sodium chloride.

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Distal Convoluted Tubule (DCT)

The section of the nephron where further fine-tuning of urine composition occurs, including potassium secretion and ammonia formation.

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Collecting Duct

The final part of the nephron where some urea, sodium chloride, and water are reabsorbed, before urine exits the kidney.

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Glomerular Filtration Rate (GFR)

Measures the rate at which blood is filtered by the kidneys, giving a measure of kidney function.

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How do post-renal causes affect kidney function?

Post-renal causes of decreased kidney function work by reducing the blood pressure inside the glomerulus, which is responsible for filtering waste.

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What are some examples of post-renal causes?

Kidney stones, prostate enlargement, and other obstructions in the urinary tract can lead to post-renal kidney dysfunction.

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What is GFR?

Glomerular Filtration Rate (GFR) is a measure of how well your kidneys filter waste from your blood.

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What is proteinuria?

Proteinuria is the presence of excessive protein in urine, often indicating kidney damage.

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What is albuminuria?

Albuminuria is a specific type of proteinuria where albumin, a common protein in blood, is found in urine.

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Can urine albumin or protein levels be elevated without kidney disease?

Urine albumin or protein levels might be elevated due to factors unrelated to kidney conditions.

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What role do urinary tract infections play in urine protein levels?

Urinary tract infections can cause an increase in urine protein levels without affecting kidney function.

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Why are laboratory tests important for kidney function?

Clinical tests like GFR and proteinuria assessments help doctors understand kidney health and identify potential issues.

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Tubular concentrating ability

The ability of the kidneys to concentrate urine, which is the first function to be impaired in tubular damage.

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Causes of impaired tubular concentrating ability

A group of conditions that can damage the kidney tubules and impair their ability to concentrate urine.

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Dilution test

A test that measures the ability of the kidneys to excrete dilute urine by administering a large volume of fluids and monitoring urine specific gravity and osmolality over a period of 3-4 hours.

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Specific gravity (Sp. Gr.)

The specific gravity is the ratio of the weight of a substance to the weight of an equal volume of water at a specific temperature.

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Specific gravity and kidney function

Specific gravity measures the concentration of chemical particles in urine and is one way to assess kidney function.

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Specific gravity vs. osmolality

Specific gravity is directly related to the number of particles in urine, but not a perfect measure of concentration like osmolality.

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Limitations of dilution tests

Dilution tests are not always reliable as they can be affected by factors beyond kidney function, such as adrenal insufficiency, hepatic disease, cardiac failure, emotional state, and fluid excretion limitations.

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Normal dilution test results

A normal dilution test result should show at least one urine specimen with a specific gravity below 1.003 and should have excreted at least half of the ingested water within 3-4 hours.

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Osmolality

A measure of the concentration of dissolved particles in a solution, reflecting the osmotic pressure exerted by those particles.

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Urine Specific Gravity

The ability of the kidneys to concentrate urine, demonstrating the function of the renal tubules.

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Osmotic Clearance

A test that measures the concentration of osmotically active particles in urine compared to serum, reflecting the kidney's ability to concentrate urine.

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Acidification of Urine

The process by which the kidneys regulate the pH of urine by eliminating excess acids.

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Urine Osmolality to Serum Osmolality Ratio

The ratio of urine osmolality to serum osmolality, reflecting the kidney's ability to concentrate urine.

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Glycosuria

A condition where the concentration of glucose in the urine is elevated, indicating the kidneys are unable to reabsorb glucose.

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Renal Tubular Function

The process by which the kidneys remove waste products from the blood and eliminate them in urine.

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Renal Tubular Damage

Conditions that damage the renal tubules, affecting their ability to concentrate urine.

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What is renal tubular acidosis (RTA)?

Renal tubular acidosis (RTA) is a condition where the kidneys are unable to effectively remove acid from the blood, leading to an excess of acid in the bloodstream.

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Why is blood flow crucial for kidney function?

Adequate blood flow is essential for healthy kidney function. Any disruption to this flow can negatively impact the kidneys' ability to filter waste and regulate fluids.

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What happens when blood flow to the kidneys is reduced?

Reduced kidney function due to insufficient blood flow can lead to a decline in filtering waste products, alterations in urine composition, and an accumulation of metabolic byproducts in the blood.

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How does cardiac failure affect kidney function?

Cardiac failure can lead to reduced kidney function, not because the kidneys themselves are damaged, but because of inadequate blood flow to the kidneys.

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What is glomerulonephritis and how does it affect the kidneys?

Glomerulonephritis is a condition where the glomeruli (tiny filtering units in the kidneys) are damaged, allowing protein and red blood cells to leak into the urine.

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How do nephrotic syndrome and chronic glomerulonephritis affect kidney function?

Nephrotic syndrome and chronic glomerulonephritis are conditions where the kidneys lose large amounts of protein in the urine due to damage to the glomeruli.

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How can hemolytic reactions affect kidney function?

Hemolytic reactions can severely damage nephrons (functional units of the kidneys) by overloading them with toxic substances like hemoglobin.

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How can poisons affect kidney function?

Poisons can selectively interfere with specific functions of the kidney tubules, leading to impaired kidney function.

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Study Notes

Kidney Function

  • The kidneys are bean-shaped organs located retroperitoneally in the upper abdominal quadrants.
  • They consist of cortex and medulla, and are part of the urinary system.
  • The functional unit of the kidney is the nephron, which includes the glomerulus and the tubule.
  • There are approximately 1.2 million nephrons in each kidney.
  • Renal function, also called kidney function, describes how well the kidneys work.
  • The main function of the kidney in metabolism is urine formation, which involves:
    • Excretion of waste products from the blood.
    • Preservation of essential solutes.
    • Regulation of hydration and electrolytes.
  • Kidneys have a rich blood supply.
  • The vasa recta capillaries, arising from efferent arterioles, supply the medulla with oxygen and nutrients.
  • Peritubular capillaries provide oxygen and nutrients to the renal cortex.
  • Claude Bernard recognized the importance of maintaining homeostasis for the body's integrity.
  • Homer Smith noted that the composition of blood is determined by kidney function, not dietary intake.
  • Urine production involves filtration, reabsorption, secretion, and excretion.
  • The renal artery enters the kidney, and the renal vein and ureter leave the kidney.
  • A nephron consists of glomerulus (filtering unit) and a renal tubule (to process filtered fluid).
  • The glomerulus filters the blood.
  • The afferent arteriole brings blood to the glomerulus.
  • The efferent arteriole carries blood out of the glomerulus that has not been filtered.
  • The renal corpuscle filters blood, and the renal tubule processes the filtered fluid.
  • Filtration occurs through the glomerular membrane.
  • Important molecules like plasma proteins cannot pass through the membrane.
  • Substances like sodium, potassium, amino acids, and metabolites pass through.
  • Filtration rate (GFR) measures plasma flow through the glomerulus.
  • Normal GFR for adult males is 90-120 ml/min.
  • Tubular processes concentrate and modify the filtrate, with sections like PCT, Loop of Henle, DCT, and collecting tubules.
  • Important substances like glucose, amino acids, and water are reabsorbed by the PCT and other sections.
  • Waste products like creatinine and some drugs are secreted into the tubules.
  • The kidneys play a role in maintaining fluid balance.
  • The kidneys maintain electrolyte levels through selective excretion and reabsorption.
  • The kidneys produce erythropoietin to stimulate red blood cell production.
  • The kidneys remove waste products and excess water.

Kidney Function Tests

  • Clinical tests evaluate kidney function, including tests for GFR (glomerular filtration rate) and proteinuria (albuminuria), to identify if kidney function tests are normal.
  • Inulin clearance test measures GFR; creatinine clearance is also used.
  • The PAH (para-aminohippuric acid) test measures renal plasma flow.
  • Concentration tests measure the kidneys' ability to concentrate urine by examining specific gravity (or osmolality) after an overnight period of fluid restriction.
  • Dilution tests assess ability to excrete dilute urine after a period of high fluid intake by examining specific gravity (or osmolality).
  • Dye excretion tests, like the PSP (phenolsulfonphthalein) test, assess how well the kidneys excrete the dye.

Kidney Diseases

  • Kidney damage from any cause leads to reduced kidney function and alteration of urine output.
  • Kidney diseases can affect the glomerulus, tubules, or both.
  • Conditions like glomerulonephritis or nephrotic syndrome cause abnormal glomerular function.
  • Obstructions like kidney stones or enlarged prostate affect urine outflow.

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MLS 313 Renal Function PDF

Description

This quiz explores the essential functions of the kidneys and their role in the urinary system. Learn about the structure of nephrons, the process of urine formation, and how kidneys maintain homeostasis in the body. Test your knowledge about renal anatomy and functionality.

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