Key Terms
Protein in urine
Glomerular damage; the filter is leaking.
Glucose in urine (glycosuria)
Blood glucose exceeded transport maximum; think diabetes mellitus. Transport maximum is roughly 375 mg/min in males, 300
Ketones in urine
Body is burning fat for fuel; seen in uncontrolled diabetes mellitus or severe dietary carbohydrate/protein deficiency.
WBCs in urine
Urinary tract infection.
Leukocyte esterase
Enzyme from WBCs; indirect evidence of UTI.
Nitrites in urine
Gram-negative bacteria converted nitrate to nitrite; indirect evidence of infection.
Blood in urine
Kidney stone, cancer, or trauma. (Menstrual contamination is not pathological.)
Dark tea or cola color
Liver disease or bile duct obstruction.
Pink or red color
Active bleeding in the urinary tract.
Female urethra
~4 cm long. Short length = less barrier to fecal bacteria = higher UTI incidence.
Male urethra
~20 cm long. Four regions:
Internal urinary sphincter
Smooth muscle; involuntary; autonomic nervous system control.
External urinary sphincter
Skeletal muscle; voluntary; controlled by pudendal nerve (S2-S4 sacral plexus).
Cortical nephrons
~85% of nephrons; short loops of Henle that stay in cortex.
Juxtamedullary nephrons
~15%; long loops of Henle that extend deep into medulla; critical for creating the concentration gradient used in urine