Human Central Nervous System and Peripheral Nervous System Connections

The central nervous system (CNS) of the human consists of the brain, spinal cord, and cranial nerve II (the optic nerve which connects to the eyeball).

When compared to the peripheral nervous system (PNS), the CNS differs in several key ways. It’s largely autonomic (requires no input for it to work) instead of voluntary, is much more protected (by bone and the blood-brain barrier), and interprets input, rather than integrating it.

As the PNS is much less protected, it’s vulnerable to damage by toxins, disease, mechanical injury, and autoimmune disorders. The degenerative conditions of the CNS are almost always hereditary.

Dictionnaire Universel d'Histoire Naturelle. Charles d'Orbigny, 1849.


October 7th 1849: Edgar Allan Poe dies

On this day in 1849, the American poet and writer Edgar Allan Poe died in Baltimore. Born in Boston, Massachusetts in 1809, the young Poe barely knew his parents, with his father leaving the family and his mother passing away when he was just three years old. He lived with another couple as foster-parents, and was forced to gamble to pay for his tuition at the University of Virginia, which he had to drop out of due to financial difficulties. Poe soon joined the army and was even accepted into West Point, though he was expelled a year into his studies. After leaving the academy, Poe turned his full attention to his longstanding hobby of writing. He then traveled around Northern cities, including New York, Philadelphia, and Baltimore; it was in Baltimore, in 1836, that he married his young cousin Virginia. In Richmond, Poe worked as a critic for various magazines, occasionally publishing his original work which included short stories and poems. In 1841, Poe published his ‘Murders in the Rue Morgue’, which many consider the beginning of the genre of detective fiction. His most famous work, the poem ‘The Raven’, was published in 1845 to critical praise. Sadly, his wife died from tuberculosis two years later, leaving the writer grief-stricken and nearly destitute, as he never had great financial success.  On October 3rd, he was found ill in Baltimore and taken to hospital, where he died on October 7th aged 40. It is still unknown what his precise cause of death was, but alcoholism is widely believed to have played a part. While not appreciated in his lifetime, Poe is now considered one of the great American writers.

“Lord, help my poor soul”
- Poe’s last words

“Portrait of Queen Anna of the Netherlands, née Grand Duchess Anna Pavlovna of Russia” (1849) (detail) by Nicaise de Keyser (1813-1887).


September 26th 1849: Pavlov born

On this day in 1849, the famous Russian physiologist Ivan Pavlov was born. Pavlov is best known for his research into classical conditioning. He experimented with dogs, researching how they would salivate in response to being fed. Each time Pavlov fed the dogs he rang a bell, and noticed that the dogs would salivate upon the sound of the bell, even if they were not being fed. Pavlov was thus a pioneer in the field of conditioning responses, and his experiments have coined the word ‘pavlovian’. Ivan Pavlov won the Nobel Prize for Physiology or Medicine in 1904, and died in Leningrad in 1936 aged 86.