The function of sneezing is to expel mucus containing foreign particles or irritants and cleanse the nasal cavity. During a sneeze, the soft palate and palatine uvula depress while the back of the tongue elevates to partially close the passage to the mouth, creating a venturi (similar to a carburetor) due to Bernoulli's principle so that air ejected from the lungs is accelerated through the mouth and thus creating a low pressure point at the back of the nose. This way air is forced in through the front of the nose and the expelled mucus and contaminants are launched out the mouth. Sneezing with the mouth closed does expel mucus through the nose but is not recommended because it creates a very high pressure in the head and is potentially harmful.
Sneezing cannot occur during sleep due to REM atonia – a bodily state where motor neurons are not stimulated and reflex signals are not relayed to the brain. Sufficient external stimulants, however, may cause a person to wake from sleep to sneeze, but any sneezing occurring afterwards would take place with a partially awake status at minimum.
Sneezing typically occurs when foreign particles or sufficient external stimulants pass through the nasal hairs to reach the nasal mucosa. This triggers the release of histamines, which irritate the nerve cells in the nose, resulting in signals being sent to the brain to initiate the sneeze through the trigeminal nerve network. The brain then relates this initial signal, activates the pharyngeal and tracheal muscles and creates a large opening of the nasal and oral cavities, resulting in a powerful release of air and bioparticles. The powerful nature of a sneeze is attributed to its involvement of numerous organs of the upper body – it is a reflexive response involving the face, throat, and chest muscles. Sneezing is also triggered by sinus nerve stimulation caused by nasal congestion and allergies.
History
In ancient Greece, sneezes were believed to be prophetic signs from the gods. In 401 BC, for instance, the Athenian general Xenophon gave a speech exhorting his fellow soldiers to fight against the Persians. A soldier underscored his conclusion with a sneeze. Thinking that this sneeze was a favorable sign from the gods, the soldiers were impressed. Another divine moment of sneezing for the Greeks occurs in the story of Odysseus. His waiting wife Penelope, hearing Odysseus may be alive, says that he and his son would take revenge on the suitors if he were to return. At that moment, their son sneezes loudly and Penelope laughs with joy, reassured that it is a sign from the gods (Odyssey 17: 541-550). It may be because this belief survived through the centuries, that in certain parts of Greece today, when someone is asserting something and the listener sneezes promptly at the end of the assertion, the former responds "bless you and I am speaking the truth", or "bless you and here is the truth" ("γεια σου κι αλήθεια λέω", ya sou ki alithia leo, or "γεια σου και να κι η αλήθεια", ya sou ke na ki i alithia). A similar practice is also followed in India. If either the person just having made a not most obvious statement in Flemish, or some listener sneezes, often one of the listeners will say "It is beniesd", literally "It's sneezed upon", as if a proof of truth – usually self-ironically recalling this old superstitious habit, without either suggesting doubt or intending an actual confirmation, but making any apology by the sneezer for the interruption superfluous as the remark is received by smiles.
In English-speaking countries, one common verbal response to another person's sneeze is "[May God] bless you". Another less common verbal response in the United States and Canada to another's sneeze is "Gesundheit", which is a German word that means, appropriately, "health".
In non-humans
Sneezing is not confined to humans or even mammals. Many animals including cats, dogs, chickens and iguanas sneeze. African wild dogs use sneezing as a form of communication, especially when considering a consensus in a pack on whether or not to hunt. Some breeds of dog are predisposed to reverse sneezing.
- 2 pounds ground beef
- 1 egg
- 1/4 cup water
- 1/4 cup dry bread crumbs
- 1 teaspoon salt
- 1/2 teaspoon onion powder
- 1/8 teaspoon black pepper
- 1 (12-ounce) jar cocktail sauce
- 3/4 cup grape jelly
- 2 tablespoons fresh lemon juice
- In a large bowl, combine ground beef, egg, water, bread crumbs, salt, onion powder, and pepper; mix well. Form into 1-inch meatballs and set aside.
- In a soup pot, mix together cocktail sauce, jelly, and lemon juice. Bring to a boil over high heat, then add meatballs. Reduce heat to low, cover, and simmer 30 to 35 minutes, or until meatballs are cooked through.
1931 – Morley Safer, American journalist (d.2016)
- In 1945 Achille Gaggia invented the modern espresso machine which further popularized the cappuccino.
- The Mid 1990s – Cappuccino was made more widely available to North Americans as upscale coffee houses sprang up.
- Late 1990′s to Early 2000′s – Cappuccinos became popular in the United States concurrent with the boom in the American coffee industry.
- The start of the 21st Century – A modified short-cut version of the cappuccino started being served at fast-food chains.
- While steaming the milk you must pay close attention to attain the correct ratio of foam, thus making the cappuccino one of the most difficult espresso-based beverages to make properly.
- A skilled barista may create artistic shapes while he/she is pouring milk on top of the espresso coffee.
