A pulse is caused by the alternate expansion and contraction of artery walls as heart action varies blood volume within the arteries. The arteries become distended during systole, or heart contraction, and their walls contract during diastole, when the heart relaxes. The pulse, measured in beats per minute, can be felt at a number of points throughout the human body, but is most commonly palpated at the wrist or neck. Why might using the thumb for palpation lead to an inaccurate pulse reading?
Back in the day
The Cuban Missile Crisis began when US reconnaissance aircraft uncovered Soviet missiles in Cuba. The Soviets denied the existence of the weapons, but they were forced to retract their denial when the US revealed photographic evidence at the UN. President Kennedy demanded the missiles be removed, but Soviet Premier Khrushchev refused, prompting Kennedy to order a blockade of Cuba. The Soviets then demanded the withdrawal of American missiles from what country?
Born on a day like today
Leary was a famous psychologist, writer, and controversial proponent of the drug LSD. He argued that LSD could alter behavior in unprecedented and beneficial ways if used in the right setting, with the right dosage, and preferably with the guidance of professionals. His position as a symbol of the counter-culture movement made him a target of a criminal investigation and a focus for the debate about drugs in society. What popular counter-culture catchphrase did he coin?