Human Body

Your heart beats roughly a hundred thousand times every single day without any rest.

Bones are living tissue that constantly rebuilds itself throughout your entire life.

The human brain uses a large share of the body's energy even while you rest.

Skin is the largest organ of the body and covers a surprisingly large surface.

Fingernails grow faster on the hand you use most, in many cases.

A sneeze can send air out of your nose at a remarkable speed.

Stomach acid is strong enough to dissolve many things that people accidentally swallow.

Your eyes blink thousands of times a day, mostly without you noticing any of them.

The smallest bone in the human body sits inside the ear and helps hearing.

Taste buds are replaced regularly, which is why flavour perception can shift with age.

Hair grows from follicles in the skin, and each strand follows its own cycle.

Blood carries oxygen through a network of vessels that would stretch a very long way.

A yawn is contagious for many people, especially when someone nearby starts yawning too.

Muscles work in pairs, with one contracting while the opposing muscle relaxes again.

Your liver can regrow lost tissue, which is unusual among the body's internal organs.

Fingerprints form before birth and stay with you for the whole of your life.

The spine curves gently in an S shape that helps absorb shock while walking.

Ears hear sound and also hold the structures that keep your balance steady.

A reflex like pulling your hand away happens before the brain registers pain fully.

Teeth are the hardest substance in the human body, harder than any bone.

Your body contains trillions of bacteria that live mostly inside the digestive system.

Saliva keeps the mouth moist and begins breaking down food before swallowing even starts.

A full stomach stretches to hold a meal and then slowly returns to size.

Sweat cools the body by evaporating from the skin and carrying heat away.

Goose bumps are a leftover reflex from ancestors who had much thicker body hair.

The knee is the largest joint in the body and works like a hinge.

The human nose can distinguish thousands of different smells, though estimates vary quite widely.

Dreams occur mostly during a stage of sleep when the eyes move rapidly.

Light takes a tiny fraction of a second to reach the back of your eye.

Your pulse matches your heartbeat because arteries expand with each contraction of the heart.

Blushing happens when small blood vessels near the skin surface widen suddenly.

A hiccup is caused by a sudden spasm of the diaphragm muscle below the lungs.

The tongue is made of several muscles working together rather than one single muscle.

Blood is red because of iron in a protein that carries oxygen around.

Skin sheds dead cells constantly, so a large share of household dust comes from people.

Eyes see the world upside down, and the brain flips the image for you.

Breathing slows down when you sleep and speeds up during physical activity.

A baby is born with more bones than an adult because some later fuse.

The brain has no pain receptors, so it cannot feel itself being touched.

Night vision improves after your eyes adapt to darkness over several minutes.

Chewing starts digestion by breaking food into smaller pieces mixed with saliva.

Your body clock follows a daily rhythm that affects sleepiness and alertness at different hours.

Shivering is a way of generating heat by making muscles contract rapidly and repeatedly.

The ear continues to work while you sleep, which is why loud noises wake you.

Eyelashes protect the eye by catching dust and triggering a blink when touched.

A scar forms when skin repairs a wound with tissue different from the original.

Tears keep the eye surface clean and wash away small irritants throughout the day.

Your bones store minerals and release them when the body needs a steady supply.

The diaphragm is a sheet of muscle that pulls air into the lungs.

Hearing is sharpest in childhood and gradually becomes less sensitive with advancing age.

Two thirds of the human body is water, give or take, spread through tissues.

Toenails grow much more slowly than fingernails, sometimes taking a year to fully replace.