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Human Anatomy & Physiology Laboratory OER

Materials to accompany KINS 2511 and KINS 2512 Human Anatomy and Physiology labs.


  1. Describe the major functions of the urinary system. 

  2. List the three processes that take place in the nephron (i.e., filtration, reabsorption, and secretion).

  3. Describe the role of the nephron in urine production.

  4. Describe the composition of normal urine.

  5. Perform a virtual urinalysis of three samples of urine using the dipstick method and analyze the urinalysis for evidence of abnormality by comparing the results to a standard reference chart.



Urine characteristics

The urinary system has many important functions. Most of these functions are related directly to urine production and include filtration of blood, removal of nitrogenous wastes, blood volume and blood pressure regulation, acid-base balance and electrolyte regulation. Urine formation is critical to our health and is the responsibility of the nephron - the structural and functional unit in the kidney. Most of them (85%) are located in the cortex and some are located at the junction with the medulla. Each kidney has approximately one million nephrons.

Each kidney filters approximately 1 liter of blood per minute. Blood is filtered from the glomerulus, a capillary bed, into the glomerular capsule through hydrostatic pressure. The fluid, now called filtrate, then enters the renal tubule where it is then termed tubular fluid. 99% of the filtrate created will be reabsorbed during the process of urine formation.

Urine can be characterized by its composition, volume, specific gravity, color, transparency, and smell. Determining both physical characteristics and chemical composition of urine provides a great deal of information about the health of the individual. Characteristics of urine change, depending on influences such as water intake, exercise, environmental temperature, nutrient intake, and other factors. These characteristics include:  

  • Appearance: colorless to deep amber due to a pigment known as urochrome
  • Odor: as it stands, bacteria degrade urea to ammonia
  • Specific gravity: 1.003 -1.032
  • Osmolarity in mOsm/L: 50 (dilute urine)-1,200 (concentrated urine) 
  • pH range: 4.5 - 8.0, usually 6.0
  • Chemical composition: normal healthy urine is sterile and formed from filtered blood. It is mostly water (95%) with solutes such as salts (Na+, K+, Cl-, Ca2+, Mg2+, H2PO4-, SO42-, NH4+), nitrogenous wastes (urea, creatinine, uric acid), some hormones, and small quantities of ketones. Some drugs can also be found within urine.

Urine volume is an important number regulated by the kidneys. Volume of urine can range up to 18L/day, but a normal urine volume is about 1-2L/day. This volume can increase (taking a diuretic, developing diabetes (mellitus and insipidus), drinking a lot of water when staying inside and resting) or decrease (working outside on a hot day without access to water, too many aquaporins or increasing permeability of collecting duct to water). Changes in urine output are known as: 

  • Anuria - <50 ml/day 
  • Oliguria - 300-500 ml/day
  • Polyuria - >2L/day

Analysis of a patient's urine (urinalysis) is an easy, non-invasive, and quick way to determine if some diseases or infections are present. The presence of glucose, blood (erythrocytes), leukocytes, excess protein, or ketones is abnormal and indicates infection or disease.

  • Glucose is normally fully absorbed back into the body from the filtrate. Its presence in urine indicates abnormally high levels of glucose, such as that found in diabetics.
  • Erythrocytes (red blood cells) are not normally found in urine as they should not be able to pass through the filtration membrane. Their presence indicates disease or infection.
  • Leukocytes are part of the immune response and should not be found in urine. The presence of leukocytes indicates infection, such as a kidney or urinary tract infection.
  • Protein is not usually found in urine as it cannot typically pass into the filtrate. Presence of excess protein, known as proteinuria, may indicate problems with the kidney.
  • Ketones are formed during fatty acid metabolism. A small amount of ketones in urine is normal. However, excessive ketones in urine is a sign of diabetes.


McGraw Hill Online Lab 3: Urinalyses