Brain neurons blamed for dizzy spells.Brain neurons blamed for dizzy spells
In a bygone by·gone
Gone by; past: bygone days.
One, especially a grievance, that is past: Let bygones be bygones. era, fainting or dizzy spells signified a response to great passion or trauma. Modern science has since taken the romance out of these episodes, ascribing many of them to the mundane activity of standing up too quickly.
When a person stands up, a complex system called the baroreflex kicks into action: Nerve endings in key blood vessels Blood vessels
Tubular channels for blood transport, of which there are three principal types: arteries, capillaries, and veins. Only the larger arteries and veins in the body bear distinct names. detect the resulting drop in pressure and send a message to brain neurons, which respond by boosting blood pressure. Scientists know that the baroreflex often begins to fail with age, leading to dizziness, fainting spells and even stroke. But the exact nature of this failure has remained elusive.
George Hajduczok, a physiologist at the University of Iowa Not to be confused with Iowa State University.
The first faculty offered instruction at the University in March 1855 to students in the Old Mechanics Building, situated where Seashore Hall is now. In September 1855, the student body numbered 124, of which, 41 were women. in Iowa City Iowa City, city (1990 pop. 59,738), seat of Johnson co., E Iowa, on both sides of the Iowa River; founded 1839 as the capital of Iowa Territory, inc. 1853. Among its manufactures are foam rubber, animal feed, paper, and food products. The city is the seat of the Univ. , now reports evidence suggesting that the blame lies with malfunctioning neurons. He and his colleagues studied 11 elderly purebred purebred
progeny derived from at least several generations of animals of the same breed.
herds (or flocks) composed of purebred animals. Not necessarily registered animals. Distinct from crossbred herds. beagles and five young beagles. They increased blood pressure within the dogs' carotid arteries Carotid arteries
The four principal arteries of the neck and head. There are two common carotid arteries, each of which divides into the two main branches (internal and external).
Mentioned in: Endarterectomy , which contain pressure-sensing nerve endings. Young dogs quickly sensed that change and lowered the activity of the sympathetic nervous system -- which boosts blood pressure -- by 70 percent, whereas elderly beagles damped such activity by only 20 percent, the researchers found.
A separate experiment showed that elderly dogs can lower sympathetic nervous system activity as much as young dogs, but only for a few seconds -- a finding that suggests the problem lies with the brain neurons rather than the nerve endings.
Such studies may help explain why some elderly people experience dangerous swings in blood pressure. A faulty baroreflex, says Hajduczok, can cause fainting when pressure dips too low, or a stroke when pressure soars too high.