1. An enlargement at one end of each of the semicircular canals of the inner ear. Each ampulla contains a group of receptors—sensory hair cells—embedded in a gelatinous cap (cupula), which detects movement in one particular dimension, corresponding to the plane of the canal. Movement of the head causes the cupula (and the hairs within it) to bend in a direction opposite to that of the head movement (see illustration); this stimulates nerve impulses in the receptors, which are interpreted by the brain as movement in a particular dimension.
2. Any small vesicle or saclike process.
3. (ampulla of Lorenzini) See electroreceptor.
Ampulla
An inflatable sac at the end of each tube foot in the echinoids (Echinoidea). It controls water pressure in the tube foot when the muscles in its walls are contracted.
- Tobin tax
- Tobin’s q
- tobit analysis
- Tobit model
- Tobler’s first law of geography
- Tobruk, Siege of (1941–42)
- Toby Jug Nebula
- tocopherol
- Tocqueville, Alexis, Comte de (1805–59)
- Todaro model
- Todd, Alexander Robertus, Baron
- TOE
- Toeplitz matrix
- toeset
- locomotive
- locomotive principle
- locule
- locus
- locutionary act
- lode
- lodestone
- lodgement
- lodgement till
- Lodge, Sir Oliver Joseph
- Lodge, Sir Oliver Joseph (1851–1940)