Negative Feedback Loop: From 1 Different Sources
a physiological loop for the control of hormone production by a gland. High levels of a circulating hormone act to reduce production of the releasing factors triggering its own production, i.e. they have a negative *feedback on these trigger factors. As circulating levels of the hormone fall, the negative feedback is reduced and the releasing factor starts to be produced again, allowing the hormone level to rise again.
A disorder in which abnormal FAECES occur as a result of a redundant loop in the small INTESTINE. The loop obstructs the normal ?ow of the contents of the bowel, causing stagnation. The syndrome is characterised by light-yellow, smelly, fatty, bulky faeces. The patient suffers from tiredness, malaise and loss of weight. Previous abdominal surgery is sometimes the cause, but the condition can be inherited. Blockage of intestinal contents upsets the bowel’s normal bacterial balance and hinders the normal absorption of nutrients. Treatment is either with antibiotics or, if that fails, surgery.... blind loop syndrome
A negative test result for a condition that is, in fact, present.... false negative
Gram’s Method is a staining procedure that separates bacteria into those that stain (positive) and those that don’t (negative). Gram-positive bugs cause such lovely things as scarlet fever, tetanus, and anthrax, while some of the gram negs can give you cholera, plague, and the clap. This is significant to the microbiologist and the pathologist; otherwise I wouldn’t worry. Still, knowing the specifics (toss in anaerobes and aerobes as well), you can impress real medical professionals with your knowledge of the secret, arcane language of medicine.... gram-positive/negative
Many glands which produce HORMONES are in?uenced by other hormones, particularly those secreted by the HYPOTHALAMUS (a controlling centre in the brain) and the PITUITARY GLAND. If the amount of hormone produced by a gland rises, negative feedback mechanisms operate by instructing the pituitary gland, via the hypothalamus, to produce less of the stimulating hormones. This cuts activity in the target gland. Should the amount of hormone produced fall, the feedback mechanism weakens with the result that the output of stimulating hormones increases.... feedback mechanism
That part of the nephron (see KIDNEYS) between the proximal and distal convoluted tubules. It extends into the renal medulla as a hairpin-shaped loop. The ascending link of the loop actively transports sodium from the lumen of the tube to the interstitium, and this, combined with the ‘counter-current’ ?ow of ?uid through the two limbs of the loop, plays a part in concentrating the urine.... henle, loop of
Drugs used in pulmonary oedema (excess ?uid in the lungs) caused by failure of the left VENTRICLE of the HEART. DIURETICS cause an increase in excretion of URINE, thus reducing the amount of ?uid in the body. Intravenous administration of loop diuretics relieves patients’ breathlessness. They work by inhibiting resorption of ?uid in the renal tubule loops of the KIDNEYS. Frusemide and bumetanide are commonly used loop diuretic drugs that act quickly and last for six hours so that they can be given twice in 24 hours without disturbing the patient’s sleep.... loop diuretics
The probability that a person with a negative test is free of the disease and is not a false negative.... predictive value negative
the part of a kidney tubule that forms a loop extending towards the centre of the kidney. It is surrounded by blood capillaries, which absorb water and selected soluble substances back into the bloodstream. [F. G. J. Henle (1809–85), German anatomist]... henle’s loop
(ILR) a device, inserted beneath the skin of the chest, to record the heart rhythm for up to two years. It is usually used for the investigation of patients presenting with infrequent syncope (fainting) in whom arrhythmia is the suspected cause. When syncope occurs, the device can be examined using wireless technology to reveal the heart rhythm at the time of the episode.... implantable loop recorder
(loop system) a device for helping people with some types of *hearing aid or *cochlear implant to hear more effectively in certain situations. Electrical signals from a television, sound system, or microphone are passed through an amplifier to a wire that is positioned in a loop encompassing the desired listening area. This creates an electromagnetic field that can be picked up by a coil within the hearing aid or cochlear implant. Induction loops are installed in such places as public buildings, lecture theatres, classrooms, and churches. See also assistive listening device.... induction loop system
n. 1. a bend in a tubular organ, e.g. *Henle’s loop in a kidney tubule. 2. one of the patterns of dermal ridges in *fingerprints.... loop
see induction loop system.... loop system
(in psychiatry) symptoms of schizophrenia characterized by a deficiency in or absence of some aspect of functioning, such as social withdrawal, loss of initiative, and blunted affect. Compare positive symptoms.... negative symptoms
an arthritis in which rheumatoid factor or anticitrullinated protein antibodies (ACPA) are not present in the serum. See also spondyloarthropathy.... sero-negative arthritis
see blind loop syndrome.... stagnant loop syndrome
Health Encyclopedia