Stress really can turn hair grey
A 2020 study in mice found the mechanism. Acute stress fires the sympathetic nerves that reach each hair follicle. They release noradrenaline, which pushes the melanocyte stem cells there to activate all at once. The stem cell pool runs out, and the new hair grows without pigment. The loss was permanent. Blocking the noradrenaline signal in the follicle prevented the greying.
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Zhang B et al. Nature 2020;577:676–81Brain freeze has its own randomised trial
In 2002 a Canadian eighth-grader and her father, a family medicine academic, published a randomised trial of ice-cream headache in the BMJ. 145 students were randomised to eat 100 mL of ice cream either in under 5 seconds or slowly. Eating fast brought on more headaches. They ran the trial in winter to test the claim that it only happens in hot weather.
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Kaczorowski M, Kaczorowski J. BMJ 2002;325:1445Which enzyme converts fibrinogen into fibrin during coagulation?
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NCBI Bookshelf: Physiology, Coagulation Pathways@scrollmed_factsPhysiology
NCBI Bookshelf: Physiology, ExerciseWhich change shifts the oxygen–haemoglobin dissociation curve rightwards, favouring oxygen unloading?
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NCBI Bookshelf: Physiology, Oxygen TransportFruit flies exposed the body clock
Work in fruit flies revealed a clock protein that builds up at night and is broken down during the day. The discovery helped establish how cells generate an internal daily rhythm rather than merely reacting to daylight.
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Nobel Prize in Physiology or Medicine 2017: Press release@scrollmed_factsPhysiology
NCBI Bookshelf: Creatinine ClearanceDuring ventricular isovolumetric contraction, which valve configuration is present?
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NCBI Bookshelf: Physiology, Cardiac CycleHow do bile salts primarily assist dietary fat handling?
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NCBI Bookshelf: Physiology, Bile AcidsAn alveolus remains ventilated but loses its blood supply. What does this represent?
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NCBI Bookshelf: Physiology, Pulmonary Ventilation and PerfusionSmell neurons specialise their receptors
An olfactory receptor cell expresses a single receptor type, yet that receptor can recognise several odorants. Smell identity emerges from combined receptor-activation patterns rather than a separate dedicated receptor for every odour.
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Nobel Prize in Physiology or Medicine 2004: Press releaseOxygen helps label a protein for disposal
Oxygen-dependent chemical modification of HIF-1α helps the VHL system target it for degradation. Oxygen sensing can therefore work by changing a regulatory protein's survival, rather than by switching its production on and off.
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Nobel Prize in Physiology or Medicine 2019: Advanced informationYour face can strengthen a diving reflex
In a human breath-holding study, immersing the face in cold water strengthened the slowing of the heart and peripheral vasoconstriction compared with breath-holding in air. Arterial oxygen saturation also stayed higher during the immersed condition.
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Schagatay E et al. Hematological response and diving response during apnea@scrollmed_factsPhysiology
NCBI Bookshelf: Physiology, PregnancyTouch sensors came from poked cells
Ardem Patapoutian's work used mechanically sensitive cells to uncover a previously unknown class of pressure-responsive sensors. These discoveries helped explain how mechanical forces are converted into electrical signals.
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Nobel Prize in Physiology or Medicine 2021: Press release@scrollmed_factsPhysiology
NCBI Bookshelf: Physiology, REM SleepYawning has a cardiovascular signature
Human experiments detected increases in heart rate, lung volume and eye-muscle tension during or just after yawns. The pattern was not simply reproduced by taking a deep breath. What yawning ultimately achieves remains debated.
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Corey TP et al. Front Evol Neurosci 2012;3:7@scrollmed_factsPhysiology
NCBI Bookshelf: Physiology, Endocrine HormonesWhich hormone promotes glucose uptake into skeletal muscle and adipose tissue after a meal?
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NCBI Bookshelf: Endocrinology, The endocrine pancreasWhich substance cleaves angiotensinogen to begin the classical renin–angiotensin cascade?
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NCBI Bookshelf: Physiology, Renin Angiotensin SystemWhat is the typical renal effect of aldosterone in the distal nephron?
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NCBI Bookshelf: Physiology, Aldosterone@scrollmed_factsPhysiology
NCBI Bookshelf: Physiology, Temperature Regulation@scrollmed_factsPhysiology
NCBI Bookshelf: Biochemistry, Iron Absorption@scrollmed_factsPhysiology
NCBI Bookshelf: Physiology, Endocrine HormonesWhat primarily drives the rapid depolarising phase of a typical neuronal action potential?
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NCBI Bookshelf: Physiology, Action PotentialWhich fetal vessel carries blood from the pulmonary artery towards the aorta, bypassing the lungs?
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NCBI Bookshelf: Physiology, Fetal CirculationThe Coris built glycogen in a test tube
Gerty and Carl Cori did more than trace glycogen breakdown. Their experiments also used the biochemical process to make glycogen in a test tube, helping reveal that fuel storage could be understood through specific enzyme reactions.
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NobelPrize.org: Gerty Cori — FactsMatching smell sensors converge
Smell neurons carrying the same receptor type send their nerve processes towards the same glomerulus in the olfactory bulb. This convergence turns scattered chemical detection in the nose into an organised neural map.
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Nobel Prize in Physiology or Medicine 2004: Press releaseWhich renal response is promoted by ADH?
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NCBI Bookshelf: Physiology, Vasopressin@scrollmed_factsPhysiology
NCBI Bookshelf: Endocrinology, The endocrine pancreasAn abrupt fall in arterial pressure reduces baroreceptor stretch. Which autonomic response helps restore pressure?
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NCBI Bookshelf: Physiology, BaroreceptorsChilli helped uncover a heat sensor
The burning ingredient in chilli peppers helped David Julius identify a heat-sensitive receptor in sensory nerves. A familiar kitchen sensation became a tool for discovering how physical temperature becomes a nerve signal.
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Nobel Prize in Physiology or Medicine 2021: Press release@scrollmed_factsPhysiology
NCBI Bookshelf: Physiology, Endocrine HormonesWrinkled fingers reveal nerve activity
Water-wrinkled fingertips are more than soaked skin. Sympathetic vasoconstriction reduces fingertip volume, pulling the overlying skin into folds. The response can therefore offer clues about sympathetic nerve function.
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Wilder-Smith EPV. Clin Auton Res 2004;14:125–131In skeletal muscle, calcium binds which protein to permit actin–myosin interaction?
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NCBI Bookshelf: Physiology, Muscle ContractionCells read oxygen through gene control
Cells do not merely run short of fuel when oxygen changes. They possess molecular machinery that alters gene activity according to oxygen availability. Discovering this adaptive system earned a Nobel Prize.
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Nobel Prize in Physiology or Medicine 2019: Press releaseAt the neuromuscular junction, which presynaptic event directly triggers acetylcholine vesicle release?
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NCBI Bookshelf: Physiology, Neuromuscular Junction@scrollmed_factsPhysiology
NCBI Bookshelf: The Physiology of High-Altitude ExposurePregnancy lowers an iron gatekeeper
Healthy pregnancy suppresses maternal hepcidin later in gestation, helping make more iron available from food and body stores. The review notes that the mechanism behind this pregnancy-related suppression remained unknown.
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Fisher AL, Nemeth E. Am J Clin Nutr 2017;106:1567S–1574S@scrollmed_factsPhysiology
NCBI Bookshelf: Physiology, Renal Blood Flow and Filtration@scrollmed_factsPhysiology
NCBI Bookshelf: Physiology, Neuromuscular JunctionA sugar-metabolism Nobel split
The medicine Nobel for 1947 linked fuel chemistry with endocrine control: the Coris were recognised for glycogen conversion, while Bernardo Houssay was honoured for revealing an anterior pituitary hormone's role in sugar metabolism.
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Nobel Prize in Physiology or Medicine 1947: SummaryWhich expression calculates the serum anion gap when potassium is omitted?
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NCBI Bookshelf: Physiology, Acid Base Balance@scrollmed_factsPhysiology
NCBI Bookshelf: Physiology, Muscle ContractionWithin the physiological range, what happens when ventricular end-diastolic volume rises while other determinants remain unchanged?
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NCBI Bookshelf: Physiology, Frank Starling Law@scrollmed_factsPhysiology
NCBI Bookshelf: Physiology, Acid Base Balance@scrollmed_factsPhysiology
NCBI Bookshelf: Physiology, Fetal CirculationYour clock governs more than sleep
The biological clock coordinates hormone levels, body temperature and metabolism as well as sleep. Jet lag is therefore a mismatch affecting several physiological systems, not just a feeling of sleepiness at the wrong time.
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