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Greg Brown and Mitchell MoffitScientists, authors of the book "AsapSCIENCE" |
Content:
- Cracking Your Knuckles: Arthritis Risk or Not?
- Sneezing in the Sun
- Snoozing: A Detrimental Habit
- The Limits of Muscle Growth
- Body Hair: An Evolutionary Tale
- Brain Freeze: A Sweet Tooth's Nemesis
- Bad Breath: A Mouthful of Bacteria
- Nasal Drip: A Natural Defense
Cracking Your Knuckles: Arthritis Risk or Not?
When you crack your knuckles, you're causing your joints to stretch and pulling your knuckles apart. This creates more space inside the joint and decreases pressure. Inside your knees, elbows, and fingers is a special fluid that acts like a lubricant, making sure there's minimal friction. The lower pressure causes gases in this fluid, such as carbon dioxide, to form. These gases quickly fill the expanded space, causing bubbles to form. When you stretch the joint too much, the bubbles burst due to pressure, creating that popping or cracking sound. It takes about 15-30 minutes for the gases to dissolve back into the fluid, preventing you from cracking your knuckles again right away. While there's no evidence that knuckle cracking can lead to arthritis, excessive stretching of the joints can lead to general weakness and damage over time.
Sneezing in the Sun
Many of us experience the phenomenon of the photic sneeze reflex. Why do we sneeze when exposed to bright light? It's believed that a signal from the optic nerve somehow reaches the trigeminal nerve, which controls many parts of our face—the eyes, eyelids, forehead, scalp, cheeks, teeth, chin, jaw, and even our outer ear. From there, the sneeze center in the lower brain is aroused, and we sneeze. Your brain sends a signal to the muscles in your face, neck, and chest, which work together to produce the sneeze. Normally, the sneeze reflex is used to eliminate irritants from the nose. But in the case of bright light, the trigeminal nerve mistakenly tells the brain that the nose is irritated, even though it's the eyes that are being stimulated.
Snoozing: A Detrimental Habit
That snooze button on your alarm, giving you a break from the beeping every few minutes, might be doing more harm than good. Normally, your body begins preparing for wakefulness about an hour before you actually wake up. Your body temperature increases, your sleep becomes less deep, and hormones like dopamine and cortisol are released to give you the energy you need. An alarm clock often disrupts this sleep cycle and disrupts all of these processes. If you don't have a regular sleep schedule, this abrupt waking is especially unwelcome. Your body isn't quite ready to function yet.
The groggy feeling you experience in the morning can cause you to hit the snooze button. Your body may go back into sleep and enter even deeper stages of sleep. By the time the alarm goes off again, your body is once again preparing for a cycle of wakefulness—from scratch. As a result, that second alarm can leave you feeling even more tired. The solution is to establish a regular sleep schedule. Wake up at the same time every day, even on weekends. After a few weeks, your body should adjust and become less resistant to the alarm clock.
The Limits of Muscle Growth
The truth is, we all have a limit when it comes to how big our muscles can get. Muscles are controlled by a protein called myostatin, which sets the maximum potential for your muscles. This potential varies from person to person. It all depends on how much myostatin your body produces. When that limit is reached, the myostatin prevents any further growth. So, those with lower levels of myostatin have the potential for larger muscles. This explains why some people can bulk up easily, while others struggle to gain muscle mass.
Body Hair: An Evolutionary Tale
It may surprise you to learn that humans and primates have about the same number of hair follicles. It's thought that as our ancestors migrated to different areas in search of food and warmth, having a thick coat of hair became obsolete. Men and women don't have drastically different numbers of hair follicles on their bodies. However, men's hair tends to be thicker and coarser. They may also have hair on their chest, back, toes, and in their ears. Women's body hair, on the other hand, is generally fine, thin, and less noticeable. Hairiness can play a role in mate selection. Women find men with hairy chests to be healthier and more attractive. Men, on the other hand, prefer women with less body hair. It signals that she's of "reproductive age," younger, and healthier.
Brain Freeze: A Sweet Tooth's Nemesis
Your anticipation of icy refreshment can be spoiled when your brain responds with a crippling "brain freeze." This intense but thankfully short-lived pain usually lasts no longer than 20 seconds and occurs when a cold substance touches the roof of your mouth. When you eat something cold like ice cream, the capillaries in your throat narrow. This is a normal response to the cold, as your body attempts to keep your vital organs warm. This constriction is not what causes the pain, though. It's the extra blood flowing to your brain in an attempt to keep it warm that creates pressure within the skull, resulting in a headache. Once the cold drink or food is removed or swallowed, the capillaries in your mouth quickly enlarge again. This can sometimes cause even more intense pain.
Bad Breath: A Mouthful of Bacteria
There are over 500 different types of bacteria that call your mouth home. These bacteria break down food particles and release volatile sulfur compounds (VSCs), which are known for their infamous rotten-egg smell. Certain foods promote the overgrowth of these bacteria. Protein-rich foods—dairy products, meat, and fish—can be broken down into VSCs. Drying agents, such as alcohol and cigarettes, create an ideal environment for bacteria to thrive. Coffee promotes an acidic and potentially sugary environment, increasing the rate at which bacteria multiply. Some fragrant foods, like onions and garlic, already contain VSC compounds, which are absorbed into the bloodstream and then released through your lungs and your body's pores—to be breathed out or sweated out.
Nasal Drip: A Natural Defense
A healthy nose pumps out about half a liter of mucus every day. Mucus is made up of water, proteins, carbohydrates, and salt. Its role is to trap dust particles, dirt, and bacteria, preventing infection from entering your respiratory system. Used-up mucus leaves the body through sneezing and blowing. However, more often than not, mucus is digested in the stomach. This happens because millions of tiny hairs in the nasal passage push the mucus towards the back of your throat. You swallow the mucus, where it's destroyed by stomach acid. Cold viruses invade the mucus membranes. Your body responds to the inflammation of the mucus cells by bringing more blood to your nose and leaking more water through the cells. This is what causes the runny nose. At the same time, white blood cells are sent out to attack the virus with strong chemicals or to gobble it up whole. The green color of mucus comes from an increase in iron-containing enzymes. These enzymes have antiseptic properties. The same enzymes are found in wasabi, a green Japanese condiment. Originally, wasabi was used to fight bacterial infections found in raw fish.
