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IN  this experimental setup, effects of nicotine from smoking can be measured with special instruments. Although the smoker absorbs relatively small amounts of nicotine, sensitive instruments can record its effect. For instance, these thermocouples record the influence of nicotine upon the body temperature. In this experiment, we see that the skin temperature gradually drops from point 80 on the graph to about 65, or 15 points. The skin temperature drops because blood vessels constrict under the influence of nicotine and less blood reaches the skin. Experiments with animals helped dramatize the effect of nicotine on the nerve cells of the heart. By applying the drug directly to the exposed nerve of a rabbit's heart, we induce a change in rhythm. To understand better what is happening, let us look at a schematic drawing. In the experiment, nicotine was applied at the spot indicated by the arrow. And this is one nerve cell called a ganglion cell. Nicotine first stimulates the nerve c...

  Veins and arteries are major players in the  circulatory system  of all  vertebrates . They work together to transport  blood  throughout the body, helping to oxygenate and remove waste from every  cell  with each heartbeat.  Arteries  carry oxygenated blood from the heart, while  veins  carry oxygen-depleted blood back to the heart.  An easy mnemonic is "A for ‘artery’ and ‘away’ (from the heart)." (The exceptions to this general rule are the pulmonary vessels. The pulmonary veins transport oxygenated blood back to the heart from the  lungs , while the pulmonary arteries move deoxygenated blood from the heart to the lungs.) As the  vessels  that are closest to the heart, arteries must contend with intense physical pressure from the blood moving forcibly through them. They pulse with each heartbeat (which is why your  pulse  is taken from an artery) and have thicker walls. Veins experience much l...

  A Life-Saving Contaminant In 1928 Scottish bacteriologist Alexander Fleming was in the process of sterilizing bacterial culture plates that had become contaminated with mold when he noticed clear zones circling mold colonies. The mold toxin responsible for killing the bacteria turned out to be penicillin, which Australian pathologist Howard Walter Florey and British biochemist Ernst Boris Chain later successfully isolated and purified to produce what became arguably the world’s most effective live-saving antibiotic. Incidentally, Fleming seemed to thrive on contamination—his other major discovery, of the antiseptic enzyme lysozyme in 1921, was made after he had accidentally contaminated a culture plate with his own cold germs. Population Control In the early 1920s, Austrian scientist Ludwig Haberlandt published a paper suggesting that hormones could be used as an effective means of contraception in animals. While it is unclear, he may have soon after tested a hormone preparation ...

  How Many People Actually Got Lobotomized? Today  s lobotomy   is a horror story. Less than a century ago it was a revolutionary “fix” for misunderstood mental health problems. The first lobotomies were performed in the late 1880s by Swiss physician Gottlieb Burkhardt, a supervisor of an asylum looking for ways to subdue overactive patients. Burkhardt removed parts of the brain cortex of a few patients suffering from auditory hallucinations and other symptoms of what would later be identified as  schizophrenia  or  bipolar disorder . Following the surgeries, one patient died and another committed suicide, but others were pacified. To Burkhardt and the doctors who would later follow in his footsteps, this ratio—and this result—counted as success. Still, Burkhardt’s work didn’t immediately inspire imitation. Lobotomy truly gained traction starting in 1935, when two American scientists removed the frontal lobes of chimpanzees and, in the same year, Portu...

nervous system , organized group of  cells  specialized for the conduction of electrochemical stimuli from sensory receptors through a network to the site at which a response occurs. Nervous systems are of two general types, diffuse and centralized. In the diffuse type of system, found in lower  invertebrates , there is no  brain , and neurons are distributed throughout the organism in a netlike pattern. In the centralized systems of higher invertebrates and  vertebrates , a portion of the nervous system has a dominant role in coordinating information and directing responses. This centralization reaches its culmination in vertebrates, which have a well-developed brain and  spinal cord . Impulses are carried to and from the brain and spinal cord by nerve fibres that make up the  peripheral  nervous system. All living organisms are able to detect changes within themselves and in their  environments . Changes in the external  environment ...

  The curation of this content is at the discretion of the author, and not necessarily reflective of the views of Encyclopaedia Britannica or its editorial staff. For the most accurate and up-to-date information, consult individual encyclopedia entries about the topics. Oliver F. Atkins—White House Photo/Nixon Presidential Library and Museum/NARA Greed and lust—for power as well as for sex—are the essential elements of most political scandals. Other contributing factors often include mendacity, obfuscation, obsession, moral bankruptcy, naïveté, misplaced loyalty or trust, and lapse of good judgment. Frequently, a vigilant investigative press is involved. Usually, the crucial question is Who knew what when? Sometimes the consequences for the perpetrators are dire and destructive, but sometimes the perpetrators get off scot-free. The historical impact of scandals can be transient or lasting and profound. Here’s a look at nine of the biggest political scandals in U.S. h...