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Waste Elimination

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  • Waste Elimination 
    • Urine empties from kidney nephrons → ureter → bladder → urethra
      • Ureter contains valves to prevent backflow of urine
      • Bladder is lined with transitional epithelium, which allows bladder to expand 
      • Urea recycling is when urea diffuses out of bottom of collecting duct into inner medulla, contributing to the osmotic gradient 
    • Sphincter muscles provide voluntary and involuntary control of urination
      • Internal: Smooth muscle (involuntary control) at the connection b/w bladder and urethra that keeps urine inside and prevents leaks 
      • External: skeletal muscle (voluntary control) lining the urethra