The ability to remain upright and move without falling over. Information on body position is relayed to the brain by many parts of the body: the eyes; proprioceptors (sense organs) in the skin, muscle, and joints; and the labyrinth of the inner ear. The cerebellum (part of the brain) integrates the information and sends instructions to enable various parts of the body to perform adjustments needed to maintain balance.
Disorders affecting the ear, brain, or spinal cord commonly affect balance. Ear disorders include labyrinthitis and Ménière’s disease. Less commonly, otitis media may affect balance.
Damage to nerve tracts in the spinal cord, which carry information from position sensors in the joints and muscles, can also impair balance.
This damage may result from spinal tumours, circulatory disorders, nerve degeneration due to deficiency of vitamin B12, or, rarely, tabes dorsalis (a complication of syphilis).
A tumour or stroke that affects the cerebellum may cause clumsiness of the arms and legs and other features of impaired muscular coordination.
The ability to balance is essential for a person to stand, walk and run. Maintaining this ability is a complex exercise of coordination dependent on the brain, sensory and motor nerves, and joints. There is a regular supply of information to the brain about the positions of various parts of the body and it responds with relevant instructions to the motor parts of the body. Eyes, the inner ear, skin and muscles all provide information. The cerebellum (part of the brain) collates all the information and initiates action. Balance may be affected by disorders in the balancing mechanism of the inner ear (semicircular canals) such as MENIERE’S DISEASE, and in?ammation of the labyrinth (labyrinthitis). Infection of the middle ear, such as otitis media (see under EAR, DISEASES OF), can also disturb the ability to balance, sometimes accompanied by dizziness or VERTIGO. If the cerebellum is affected by disease – a tumour or a stroke, for example – the result will be faulty muscular coordination leading to clumsiness and the inability to walk properly.
The appropriate balance of ?uid input and output (along with dissolved salts essential for life) over 24 hours. During this period, about 2,500 millilitres (ml) of ?uid should be taken in by a 70-kg man and the same amount excreted; of this, 1,500 ml will be drunk, 800 ml will be in the food eaten, and 200 ml produced by food metabolism. Excreted water is made up of 1,500 ml of urine, 800 ml insensible loss and 200 ml in the faeces. A 70-kg man’s total body ?uid is 42 litres – 60 per cent of body weight. Intracellular ?uid comprises 28 litres, extracellular, 14 litres and blood, 5 litres. Water is controlled mainly by the sodium concentration in the body ?uids via the release of antidiuretic hormone (ADH – see VASOPRESSIN) from the posterior part of the PITUITARY GLAND. In seriously ill people, close monitoring of ?uid intake and output, along with measurements of PLASMA sodium and calcium concentrations, is an essential factor in treatment.... fluid balance
(BSS) a solution containing physiological concentrations of sodium chloride, potassium chloride, calcium chloride, magnesium chloride, sodium acetate, and sodium citrate. Such fluids are isotonic to eye tissue; they are used during intraocular surgery and to replace intraocular fluids.... balanced salt solution
the relationship between the nitrogen taken into the body and that excreted, denoting the balance between the manufacture and breakdown of the body mass. A negative nitrogen balance, when excretion exceeds intake, is usual after injury or operations as the energy requirements of the body are met disproportionately from endogenous sources.... nitrogen balance
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