Archive for the ‘human body’ Category
How come when you eat sour candy you make weird faces?
How come when you eat sour candy you make weird faces? asks Danielle Vollono, a student in Brookville, NY.
It’s how we decode dinner: Scientists say there are at least four basic tastes — sweet, salty, sour and bitter. (Some add a fifth, umami, the savory taste provided by an amino acid in food called glutamate.) While we have generally pleasant reactions to sweet and salty tastes, it’s a different story with “bitter” and “sour.” “Bitter” may mean poison, so our brain is hard-wired to reactive negatively to the taste. “Sour” may mean a food is spoiled, and full of harmful bacteria.
When given a taste of something bitter, newborn babies make an immediate expression of disgust, and turn their faces away. But when tasting something sour, like lemon juice, an infant’s reaction is usually slower and milder. The lips purse and pucker, the nose wrinkles, the eyes narrow. Over a period of seconds, the baby may close her mouth and retract her lips, or frown.
But as babies get a few months older, some may actually smile at the taste of lemon juice. Human beings seem to have a love/hate relationship with sour tastes, even at 4 months old. Which is why some of us enjoy endless varieties of sour candy — and lemons — even as we pucker our lips and scrunch up our face.
How come your funny bone is called your funny bone?
How come your funny bone is called your funny bone? asks Noah Kennedy White.
If you’ve ever hit your funny bone, you know that the only amusement comes from the faces, gestures, and sounds you make as you grab your elbow and dance around the room. The vibrating pain, extending to your fingers, seems to start in the knobby bone on the inner elbow. Actually, the bone is an innocent bystander; it’s a nearby nerve that’s causing all the excruciating commotion.
It should be called the Funny Nerve, but its official name is the ulnar nerve (after the ulna bone in the forearm). Stretching from neck to hand, the ulnar nerve sends impulses back and forth from the spine.
The pain from hitting the ulnar nerve is no laughing matter. Smaller nerves running through the skin allow us to sense heat and cold, or to feel the prick of a thorn before it pierces the skin. These nerves are relatively unprotected, so that we can perceive the world around us. But the ulnar nerve is a big nerve. Its main function is to control muscles in the forearm and hand, as well as enabling our pinky and ring fingers to feel sensations.
Other large nerves are protected by bone and fat. But the ulnar nerve is almost completely exposed. The ulnar nerve runs in a bony groove (the “cubital tunnel”) through the elbow, where all that stands between desktop and nerve is an thin layer of fat and skin.