20 surprising facts about the human body

Our body is the most amazing machine in the world, working day and night without a break — even while we sleep. Here are 20 facts about the human body that will help in science class and inspire you to look after your body.

Bones and muscles

1. An adult body has 206 bones, while a newborn baby has about 270 to 300 — many bones fuse together as we grow.
2. The smallest bone is the stapes (stirrup) inside the ear, and the longest is the femur in the thigh.
3. The masseter muscle of the jaw is counted, for its size, among the most powerful muscles in the body.
4. The body has more than 600 muscles, which work with the bones to make every movement possible.

Heart and blood

1. The heart beats about one lakh (100,000) times a day.
2. An adult body holds about 5 litres of blood.
3. If all the blood vessels were laid end to end, their length is said to be about one lakh (100,000) kilometres — two and a half times round the Earth.
4. Red blood cells live for about 120 days; then the bone marrow makes new ones.

Did you know? Every person in the world has different fingerprints — even identical twins. That is why fingerprints are used for identification and investigation.

Brain and senses

1. The brain is only about 2 per cent of the body's weight, but it uses about 20 per cent of the body's energy.
2. We blink about 15 to 20 times a minute, which keeps the eyes moist and clean.
3. Our tongue has thousands of taste buds, which recognise sweet, sour, salty, bitter and umami tastes.
4. Normal body temperature is taken to be about 37 degrees Celsius (98.6°F).

Internal organs

1. The skin is the body's largest organ, and the liver is the largest internal organ.
2. The liver has an amazing ability to rebuild itself — if part of it is removed, it can grow back.
3. Together the two kidneys filter about 180 litres of fluid a day, and the body takes most of that water back.
4. The small intestine is about 6 metres long — most of the digestion and absorption of food happens here.
5. The right lung is divided into three parts (lobes) and the left into two; the left lung leaves room for the heart.
6. The stomach holds a strong acid that digests food (hydrochloric acid); its inner lining is renewed every few days so that the stomach does not digest itself.

What the body is made of

1. About 60 per cent of our body is water — which is why drinking enough water every day matters.
2. Hair and nails are made of a protein called keratin — the same protein found in birds' feathers and animals' horns.

One thing is clear from these facts: our body does its job faithfully. In return it needs a balanced diet, water, good sleep and a little exercise every day.

Read more: Class 4 quiz: our body and food · Science questions.