PhysiologyLesson 1 of 10 in the course The Urinary System

Normal Urine Characteristics and Abnormal Urinalysis Findings

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Urine reflects the work of the kidneys and can provide useful clues about hydration and health. This lesson introduces how filtrate becomes urine and how normal urine volume, color, odor, pH, and concentration vary.

Each kidney contains specialized capillary tufts called glomeruli. Together, the two kidneys have about 2 to 3 million glomeruli. These structures filter blood mainly according to particle size. Blood cells, platelets, antibodies, and most albumin are too large to pass through the filtration barrier, while water and many smaller solutes enter the filtrate.

All flashcards

Urochrome
The yellow urine pigment produced through processing of heme from hemoglobin breakdown.
Polyuria, oliguria, and anuria
Polyuria is generally over 2.5 L/day; oliguria is often below 500 mL/day; anuria is virtually absent output, defined here as below 50 mL/day.
Specific gravity and osmolarity
Specific gravity estimates urine solute content relative to water; osmolarity directly measures dissolved-particle concentration.
Proteinuria
Excess protein in urine, which can indicate damage to the glomerular filtration barrier.
Leukocyte esterase
An enzyme released by white blood cells; its presence indirectly indicates leukocytes in urine.

Quiz questions

  1. Why is daily urine output normally much smaller than the volume of filtrate produced?Answer: Nephron tubules reabsorb most filtered water and useful substances.
  2. What can excess protein in urine indicate?Answer: Damage to the glomerular filtration barrier that allows protein to pass.
  3. What does leukocyte esterase in a urine sample suggest?Answer: White blood cells may be present, providing an indirect clue to infection or inflammation.
  4. How can some gram-negative bacteria produce a positive nitrite result in urine?Answer: They convert nitrate in the urine into nitrite.
  5. How can glucose enter urine in diabetes mellitus?Answer: Blood glucose can exceed the capacity of renal sodium-glucose transporters.

Based on Anatomy and Physiology 2e by J. Gordon Betts, Kelly A. Young, James A. Wise, Eddie Johnson, Brandon Poe, Dean H. Kruse, Oksana Korol, Jody E. Johnson, Mark Womble, Peter DeSaix (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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