Human Quiz Answers

by Deb on August 20, 2011

Humans

How did you do? I mean it’s your body, you got all the answers didn’t you? If you haven’t done yesterday’s quiz, shut your eyes and go back.

1.   The talus transmits the entire weight of your body into your feet – it’s the only bone that has to transmit the whole body weight. It is all about stabilising your ankle so you can walk and is attached to lots of other bones (4 – tibia, fibula, calcaneus, navicular). It gives us the ankle hinge movement essential for walking, and lets our feet twist and rotate to cope with surfaces that aren’t completely flat. But it isn’t attached to any muscles or tendons. There is nothing pulling and moving on it, it’s a bit like the pin in a door hinge.

Ankle

Talus in the middle of the ankle and foot bones.

2.   Midgut herniation is not only normal, it’s extremely important! Ever wondered how your small intestines got twisted up so they can fit around 5 m coiled into your abdomen? Early in development, from around 7 weeks up to 11 weeks, the embryo has no front abdominal wall and the cavity opens directly into the umbilicus. The developing intestines grow out into the umbilical cord as the midgut herniation, then coil themselves back in to end up in the proper place for the small intestines.

midgut herniation

Midgut herniation beginning to grow into the umbilical cord.

3.   There are two types of melanin – eumelanin and phaeomelanin. Everyone has some phaeomelanin in their hair, most people have more eumelanin. There are two subtypes of eumelanin, brown and black, which produce blonde – brown and grey – black hair. Redheads have more phaeomelanin because of a mutation that knocks out the MC1R receptor. This isn’t a single mutation – the receptor needs to be switched on to produce eumelanin and many changes can knock it out. While it isn’t quite true to say all redheads are redheaded in their own unique way, there are certainly lots of different ways of being redheaded.

What’s really cool is that the MC1R receptor appears to react to other hormones and chemicals as well as the ones involved in colour. This includes some of the endorphins and pain signals – red heads actually respond to pain and anaesthetics differently to blondes and brunettes. It’s also been found that women respond to painkillers differently to men. These types of discoveries are leading research closer and closer to individualised drugs that are tailored to our genes. redhead

4.    The gluteals, gluteus maximus, medius and minimus, are the muscles on your backside and are your biggest muscles. Humans do a very peculiar thing, walking upright, without a long tail or horizontal body to balance us out. Somehow we have to balance as a long vertical column. The reason the gluteals are so big is they are one of the muscles that help keep us up by pulling the trunk and thighs into line. This also helps us stand and climb.

5.   The photo is a healthy ear drum. Around the outside is the skin and blood vessels of the ear canal, then the translucent membrane of the ear drum. This is so thin it is pushed by the moving molecules of air that make sounds. At the top are the arteries and nerve that serve the ear drum, and behind it you can see the malleus (hammer), the first of three tiny bones that transmit the movements into the inner ear. Have a look at the video below to see another healthy ear drum with explanations.

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{ 1 comment… read it below or add one }

Barry Wheeler August 22, 2011 at 3:17 am

Interesting! My first thought was this was an enlarged vew of the human eye. But something didn’t seem just right! 🙂

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