A distensible membranous sac that serves as receptacle for bodily fluids or gases. A vital organ in mammals. Examples are the urinary bladder (when it's full, you have to take a leak)and the swim bladder (helps fish with breathing).

The bladder from dead animals is often used in a sports utensil called a ball. See also: basketball, soccer, bladder infection.

In humans the urinary bladder is a triangular muscular bag that temporarily stores urine before voiding.

It lies anterior to the rectum in the male and anterior to the vagina in females. In both sexes it lies behind the pubic symphysis.

The mucosa (inner lining) of the bladder is transitional epithelium with rugae. The folds (rugae) allow it to expand as it fills. As it fills with urine, stretch receptors steadily increase the urge to pee.

Blad"der (?), n. [OE. bladder, bleddre, AS. bldre, blddre; akin to Icel. blara, SW. bladdra, Dan. blaere, D. blaar, OHG. blatara the bladder in the body of animals, G. blatter blister, bustule; all fr. the same root as AS. blawan, E. blow, to puff. See Blow to puff.]

1. Anat.

A bag or sac in animals, which serves as the receptacle of some fluid; as, the urinary bladder; the gall bladder; -- applied especially to the urinary bladder, either within the animal, or when taken out and inflated with air.


Any vesicle or blister, especially if filled with air, or a thin, watery fluid.

3. Bot.

A distended, membranaceous pericarp.


Anything inflated, empty, or unsound.

"To swim with bladders of philosophy."


Bladder nut, or Bladder tree Bot., a genus of plants (Staphylea) with bladderlike seed pods. -- Bladder pod Bot., a genus of low herbs (Vesicaria) with inflated seed pods. -- Bladdor senna Bot., a genus of shrubs (Colutea), with membranaceous, inflated pods. -- Bladder worm Zool., the larva of any species of tapeworm (Taenia), found in the flesh or other parts of animals. See Measle, Cysticercus. -- Bladder wrack Bot., the common black rock weed of the seacoast (Fucus nodosus and F. vesiculosus) -- called also bladder tangle. See Wrack.


© Webster 1913.

Blad"der, v. t. [imp. & p. p. Bladdered (#); p. pr. & vb. n. Bladdering.]


To swell out like a bladder with air; to inflate.


G. Fletcher.


To put up in bladders; as, bladdered lard.


© Webster 1913.

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