Human Body — Page 6
The incredible human body
267 facts
There is a reflex that makes you sneeze when you look at the sun.
The photic sneeze reflex affects about 18 to 35 percent of people. When sunlight suddenly enters the eyes, the optic…
Fingerprints form in the fetus before birth.
Fingerprints begin to form in the fetus around the 10th week of pregnancy and are fully formed by 4 months. They are…
Collagen is the most abundant protein in the human body.
Collagen represents about 30 percent of all proteins in the human body and is the main component of skin, bones…
Body temperature varies throughout the day.
Body temperature is not constant. It is lowest in the morning, around 4 a.m., and highest in the late afternoon. This…
Goosebumps are a useful reflex for modern humans.
Goosebumps are a vestigial reflex inherited from our hairy ancestors. When they were cold, the hairs stood up to…
A mutation in the LRP5 gene can make bones extremely dense and difficult to break.
A mutation in the LRP5 gene can make bones extremely dense and hard to break. People with this mutation rarely suffer…
The human body has more bacteria than its own cells.
For decades it was thought that the human body had ten times more bacteria than its own cells. Recent studies show…
The thymus grows throughout life.
The thymus is a gland of the immune system that reaches its maximum size at puberty and then gradually shrinks, being…
The pineal gland produces melatonin, the sleep hormone.
The pineal gland, located in the centre of the brain, produces melatonin, a hormone that regulates the sleep-wake…
The pituitary gland is the largest gland in the human body.
The pituitary gland is the size of a pea, about 1 centimetre in diameter and 0.5 grams. Despite its tiny size, it…
The thyroid has the shape of a butterfly.
The thyroid is an endocrine gland located in the neck, shaped like a butterfly or a shield. It produces hormones that…
The adrenal glands are larger than the kidneys.
The adrenal glands are small endocrine glands located on top of each kidney. Each weighs about 5 grams, much smaller…
The human body can withstand the same temperature in icy water as in icy air.
The human body loses heat much faster in water than in air. Water conducts heat about 25 times better than air, which…
The left ventricle of the heart is the strongest chamber.
The left ventricle of the human heart has a muscular wall about three times thicker than the right ventricle. This is…
Tooth enamel regenerates naturally.
Tooth enamel does not regenerate. Once worn down or damaged, it does not grow back, unlike bones. That is why dental…
The liver filters about 1.4 litres of blood per minute.
The human liver is one of the most active organs in the body. Every minute, it filters about 1.4 litres of blood…
The human small intestine is about 7 metres long.
The human small intestine is about 7 metres long, divided into the duodenum, jejunum and ileum. The villi inside…
The fastest muscle in the human body is in the eyelid.
The orbicularis oculi muscle, responsible for blinking, is the fastest in the human body. Each blink lasts only about…
Blinking helps clean and lubricate the cornea.
Each blink spreads a film of tears over the cornea, removing dust and microorganisms and keeping the eye surface…
The hyoid bone is the only bone in the human body that is not connected to any other bone.
The hyoid bone, located at the base of the tongue, does not articulate directly with any other bone. It is supported…
The interstitium is a new human organ discovered in 2018 that runs throughout the body.
The interstitium is a network of fluid-filled spaces between tissues, present under the skin and between organs…
The muscle that tries to move human ears still activates when we try to hear something difficult.
The auricular posterior muscle, an evolutionary vestige, contracts when we make an effort to hear difficult sounds…
The human stomach replaces its lining every three to four days.
Gastric acid is strong enough to digest metal, so the stomach needs to generate a new layer of mucus and epithelial…
The nose and ears appear to grow throughout life due to gravity.
They do not actually grow through cell division, but the cartilage loses elasticity and gravity pulls the tissues…