What is hair made from and why does the funny bone get on our nerves?

What is hair made of?

Hair is made from cells called epithelial cells, which are arranged in three layers. The innermost layer is the medulla, the middle layer is the cortex and the outer layer is the cuticle. The medulla is mainly soft keratin (a protein) and the cortex and cuticle are mainly hard keratin. This structure has great strength – a strand of hair is stronger than an equally thick strand of nylon or copper wire.

What determines how tall you grow?

Your adult height is determined by genetics and nutrition – with genetics playing the major part. If you are tall but your parents aren’t, it’s very likely that somewhere along your family line you had tall relatives, so the genes for a tall person are there even though your father and mother are of average height. But nutrition can also be a factor. Some researchers are testing whether there is a particular stage during development when a good diet can greatly affect your height.

Nutrition becomes a limiting factor on height only when malnutrition occurs or there is a lack of essential vitamins and minerals; so it’s only partly true that there is a relationship between how much you eat and your height.

How much heat does the human body give off?

Curiously, men typically give off more heat than women – between 158 and 167 kilojoules per “square metre of skin in men and 150-158 kilojoules per square metre in women. Adult men have about two square metres of skin, and so give out about 326 kilojoules from their bodies each hour – that is, just over 90 watts.

What makes us sleepy?

A tiny, pea-like blob at the base of the brain – the pineal gland – seems to be important. It produces a chemical, melatonin, particularly in late evening, and this makes us feel sleepy. Scientists are trying to find out more about such substances.

What is the recommended daily intake of salt for an adult?

Our bodies need 1 gram of sodium chloride (salt) a day to survive. The UK average intake for adults is 8 to 10 grams a day. For health reasons, it is recommended that this be reduced to 5 to 6 grams – equivalent to a slightly heaped teaspoonful.

Do ears continue to grow after maturity?

Yes, earlobes can continue to grow, but generally once the head has stopped growing, so do the ears.

What is the funny bone?

The funny bone is actually a nerve that runs through a groove in a bone very close to the surface of your skin. It’s called the ulnar nerve because it runs through the ulna, the outer of the two bones of the forearm. The ulnar nerve provides sensations for the wrist and hand.

At the elbow, the ulna sticks out, and both it and the ulnar nerve are very close to the skin, making them easy to bump or knock. If the nerve itself is hit, you get a very painful physical reaction, and “when things hurt a lot, you get very emotional, which means you laugh (or cry, or both) a lot.