6. The cornea is the only part of the human body which has no blood supply. As such, it has to draw its amount of oxygen directly from the air.
The cornea is the outer layer of the eye that gives it a lens shape and cushions the aqueous humor. It is specialized tissue with unmyelinated, super-sensitive nerve endings. However, due to the nature of its work, the cornea gets oxygen either by diffusion through the aqueous humor or directly through the air.
Blood carrying oxygen cannot be supplied directly to the cornea because this part of the eye needs to be transparent to allow in light. The nutrients diffuse through the tears and are transported to the cornea from outside. However, the cornea has active cells that need a constant supply of oxygen. And because it is located on the outer part of the eye, it gets its oxygen directly from the air and continues to perform its task fo allowing in light for humans to see. (1, 2)
7. Both humans and domestic dogs elicit a dramatic increase of oxytocin, the bonding hormone, from the other when staring into each other’s eyes. This is similar to a human mother and her infant.
Dogs are known to be the most excellent of companions to humans than any other animal. Research shows that the high social skills in dogs are related to the oxytocin hormone. And this hormone is also suspected of having contributed to the domestication of dogs. The oxytocin hormone is the same hormone responsible for social bonding in humans. It is produced in the hypothalamus and released into the bloodstream by the pituitary glands.
A research done by Takefumi Kikusui found that a gaze initiated by a dog had a profound impact on the oxytocin levels on the pet owner. The team concluded that humans domesticated dogs and not wolves because of their ability to bond. (1, 2, 3)
8. Humans get goosebumps because of an evolutionary trait that was used to make fur stand up to make the animal appear larger.
The word “goosebump” was coined from the bird named “goose.” The tiny protrusions seen on the bird when its feathers are plucked are like those seen on human skin. The reason why we see goosebumps traces back to human ancestors. The apes raise their fur in a reflex action to make them appear big and scare away their enemies. Also, they raise their fur when they need to trap in more air for insulation. And since humans do not have long hair, all we see are goosebumps on the skin.
This reflex action in humans is known as “piloerection” and is caused by freezing temperatures, intense emotions, music, opiate withdrawal, voluntary control, and ingestion. When a human being experiences any of the above conditions, the sympathetic nervous system initiates a reflex action whereby the arrector pili muscles erect, forcing the tiny hairs on the skin to stand up. During cold temperatures, the muscles will pull the hair straight to hasten the evaporation of water from the skin surface in an attempt to regulate the temperature inside and outside the skin. Goosebumps are mostly seen on the arms, legs, and the neck. (source)
9. In weight loss, around 84% of the fat that is lost turns into carbon dioxide and leaves the body through the lungs.
Weight loss is often a trending topic, and everyone is on a spree to burn off a few calories. But where does the fat we lose go? According to research, 84% of the fat is lost through the lungs. One interesting thing to note, though, is that most health practitioners do not understand how and where the fat goes.
Fat is stored in the body cells in the form of triglyceride which consists of carbon, hydrogen, and oxygen. Oxygen taken in during exercise breaks down fats to releases energy that helps the body with the training. During this process, carbon and hydrogen atoms share the oxygen in a ratio of 2:1 to form carbon dioxide and water. These two elements are waste materials in the body. Water is released in the form of urine, sweat, and tears. Carbon dioxide, on the other hand, which forms the most substantial part of the waste material, is released through the lungs.
10. The white part of our fingernails is called “lunula.”
“Lunula” is a Latin word meaning “little moon.” This Latin name is also used to refer to the crescent-like white part of your nail. This delicate part of the nail outlines the nail structure and is not as white as you think. It appears white because of the stratum basale, the deepest layer of the dermis layers blocks the blood vessels. Any damage on the lunula and the nail’s structure will be permanently affected. (source)