Dictionary > Bladder


noun, plural: bladders
(1) (anatomy) A distensible membranous sac or organ that can hold liquid or gas
(2) (anatomy) Urinary bladder
(3) (pathology) A liquid- or air-filled vesicle, cyst, blister, etc.
(4) (botany) A float, which is an inflatable sac, such as found in some seaweeds
In anatomy, a bladder pertains to a distensible sac that can hold liquid or air. In animals such as vertebrates, the urinary bladder is an example of such organ. In humans, the urinary bladder is located at the base of the pelvis. It serves as a reservoir of urine. It collects urine from the kidneys via the ureters. The contraction of the bladder results in urination. It passes the urine via the urethra and then into the urethral orifice. The urinary bladder is capable of holding about 300 to 500 mL of urine.1
In botany, a bladder is an air-filled sac that serves as a flotation organ in certain plants, such as seaweeds. Fucus vesiculosus (bladderwrack) has air bladders that are almost spherical and often paired along its midrib. Another is Macrocystis pyrifera (giant bladder kelp). It is a large brown algae; it can grow from the bottom to the surface of the water column. It is characterized by its blades growing at irregular intervals along the stripe and a single gas bladder (particularly called pneumatocyst) at the base of each blade.2
Related term(s):

  • Bar of bladder
  • Cancer bladder
  • Urinary bladder
  • Bladder stone
  • Bladder rhabdomyosarcoma
  • Bladder cancer
  • Bladder calculi
  • Bladder calcification
  • Atonic bladder
  • Uvula of bladder
  • Uninhibited neurogenic bladder
  • Neuropathic bladder
  • Stammering of the bladder
  • Swim bladder
  • Air bladder
  • Gall bladder
  • Poorly compliant bladder


1 Boron, W. F. & Boulpaep, E. L. (2016). Medical Physiology. 3: Elsevier Health Sciences. p. 738.

2 Kain, J. M. (1991). Cultivation of attached seaweeds in Guiry, M. D. & G. Blunden (1991) Seaweed Resources in Europe: Uses and Potential. John Wiley and Sons.

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