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Many of the drugs used by neuroscientists are derived from toxic plants and venomous animals (such as snakes, spiders, snails, and puffer fish).
Signs of depression include feeling sad most of the time for 2 weeks or longer; loss of interest in things normally enjoyed; lack of energy; sleep and appetite disturbances; weight changes; feelings of hopelessness, helplessness, or worthlessness; an inability to make decisions; and thoughts of death and suicide.
Human kidneys will clean about 1 million gallons of blood in an average lifetime.
Patients who have undergone chemotherapy for the treatment of cancer often complain of a lack of mental focus; memory loss; and a general diminution in abilities such as multitasking, attention span, and general mental agility.
Sperm cells are so tiny that 400 to 500 million (400,000,000–500,000,000) of them fit onto 1 tsp.