Features

1. There are about ten times as many bacterial cells in the human body as human cells.
 
2. Newborn babies often lactate (produce breast milk), because they’re born with their mum’s hormones in their blood.
 
3. The muscle that makes men, um … retract in the cold is called the cremaster muscle. 
 
4. The appendix is a little bag that looks a bit like a tail hanging off the start of the large intestine. It doesn’t seem to have any point, and some scientists think it might be left over from when our ancestors ate more leafy things and needed an extra stomach.
 
5. The fattiest organ in your body is the brain.
 
6. The amount of energy your body can get from every gram of alcohol is in between the amount it can get from sugar and how much it can get from fat. The fresher five can’t all be blamed on Hall food.
 
7. Humans have seven vertebrae (back bones) in our necks; this is the same number as giraffes.
 
8. Nerve cells are the longest cells in the human body. Because they have to carry signals all the way from the spinal cord to, for example, your toe, they are often as much as a metre long.
 
9. Your stomach and intestines have their own nervous system, which is mostly independent of your brain. If you take out a piece of intestine from an animal (or human …) and keep it in the right conditions, it can keep moving on its own.
 
10. Blood looks red, but it’s mostly made up of a yellowy liquid called plasma, which has red and white blood cells floating in it
 
11. Onions make you cry because they release a gas that reacts with the water in your tears to make sulfuric acid.
 
12. When you look at someone you’re attracted to, your pupils dilate (get bigger). 
 
13. Asparagus makes most people’s pee smell funny – but only about a fifth of people are able to smell it.
 
14. People are born with around 300 bones, but many of them fuse as you grow up, so an adult only has 206.
 
15. The heart creates enough pressure when it pumps to squirt blood about nine metres.
 
16. It’s not true that we only use ten percent of our brains. Every bit has something important to do.
 
17. On average, people who are right-handed live longer than left-handed people.
 
18. Women are more likely to get pregnant if they orgasm during foreplay or sex. Critic doesn’t recommend this as a contraceptive measure, however. Not only is it no fun at all, the key phrase here is ‘not likely’ – note, not ‘impossible’.
 
19. A normal man will release as many as 500 million sperm when he ejaculates (comes).
 
20. There are around 100 000 kilometres of blood vessels in the body.
 
21. Toxoplasma gondii is a parasite that is passed from cats to humans. It has been linked to several psychiatric conditions, including schizophrenia. Maybe this explains the crazy cat ladies?
 
22. Women get bladder infections more often than men because their urethra, the tube leading from the bladder to the outside, is much shorter. In women, it’s usually about four centimetres. In men? Well … that depends …
 
23. Information travels from one cell to another in your brain at a minimum of 416kph.
 
24. Veins look blue because the blood in them lacks oxygen. The blood in arteries is bright red, but they are deeper into your body and not usually visible through the skin. 
 
25. The biggest muscle in the human body is the gluteus maximus in your butt cheeks.
 
26. If you notice that you often sneeze when you walk out of the dark lecture theatre into the bright Dunedin sunshine, you can blame your parents. Sneezing when suddenly exposed to bright light is called photic sneezing, and it’s a genetic condition.
 
27. Astronauts don’t burp in space. Without gravity, there is nothing to separate the gas in their stomachs from the liquid.
 
28. Your brain can’t sense pain. This is lucky, because brain surgery is always performed on conscious patients so that the doctors can monitor brain function.
 
29. The largest organ in the body is the skin. An adult man’s skin has a surface area of about 1.9 m2
 
30. TV doctors who yell “He’s flatlining, get me the paddles, stat!!!” are idiots. Defibrillation (giving the heart electric shocks) is actually done when someone’s heart is beating very irregularly – so the monitor shows lots of spiky lines, not a flatline. Flatline = death.
 
31. Humans have as many hairs per square centimetre of their bodies as chimpanzees – ours are just finer.
 
32. The acid in your stomach is strong enough to dissolve razorblades. That’s not an invitation to eat one, idiot.
 
33. The foreskins from circumcised babies can be used to make skin grafts. Apparently, one foreskin can be grown to make a graft the size of five or six football fields.
 
34. Farts are mostly gas produced by the bacteria living in the gut.
 
35. The outer layer of the eye has no blood supply; it gets oxygen straight from the air.
 
36. When you ‘hurt your funnybone’, it feels so strange because what’s actually been bumped is the nerve in that part of the arm. The name funnybone comes from a bad pun – the name of the bone in the upper arm is the ‘humerus’, which some people apparently find humorous.
 
37. The longest word in the English language (excluding words made up just to be long) is pseudopseudohypoparathyroidism, a condition that causes skeletal abnormalities.
 
38. About 1 in every 500 people has an extra rib. 
 
39. The stereotype about Asians not being able to handle their drink has some truth to it. A deficiency in an enzyme called acetaldehyde dehydrogenase, which is important in breaking down alcohol, is much more common in parts of Asia than in the West. 
 
40. The little dangly bit at the back of your throat is called the palatine uvula, and it helps to stop food going up your nose when you swallow. Some languages, such as Tinglit, a Native American language, involve using it to make sounds.
 
41. Your liver has over 500 functions. Without a functional liver, you’d die very quickly. Think of your liver this weekend – it really, really, doesn’t like it when you get OTP.
 
42. About a third of faeces (poo) consist of dead bacteria.
 
43. Sperm can survive inside the female reproductive system for five days.
 
44. The biggest blood vessel in your body is your aorta, which is the blood vessel that leaves the left side of your heart and runs downwards through your body. It has about the same diameter as a garden hose.
 
45. About half of all adults have a mite called Dermodex folliculorum living in their eyelashes.
 
46. Hair and fingernails don’t actually keep growing after you die. The rest of the body shrivels up a little, making them look longer.
 
47. A baby’s head is one-quarter of the baby’s length, but by age 25 it will only be one-eighth of its total length.
 
48. Approximately one to five percent of people have one or more extra nipples, usually on the abdomen. More rarely, some women can have extra breast tissue as well, or even entire breasts, which produce milk after childbirth and can be used to breastfeed.
 
49. Although no one really knows exactly why we hiccup, hundreds of ‘cures’ exist. One of the wackiest is ‘digital rectal massage’ – in non-medical terms, sticking a finger up someone’s bum and wiggling it around. This suggestion has actually been published in two medical journals. The real concern is the mental health of the doctor who went “Hmmm, can’t stop this guy’s hiccups – what should I try next? Oh! I know …”
 
50. When men experience a drop in social standing, their testosterone (male sex hormone) levels fall.
 
51. Babies are born with accents – they cry differently depending on their native language.
 
52. The small intestine is four times as long as the average man is tall.
 
53. Approximately 100 million acts of sexual intercourse occur somewhere in the world each day.
 
54. Hypertrichosis lanuginosa is a genetic disease that causes a thick growth of hair over the entire body apart from the soles of the feet and the palms of the hands. It’s often called ‘werewolf syndrome’ – though really they look a bit more like Wookiees.
 
55. People with gum disease are more likely to get heart problems.
 
56. On average, sex lasts for two minutes.
 
57. The ‘blueprint’ for a human is written in DNA. It is written in four ‘letters’: chemicals called adenine, guanine, thymine, and cytosine. Each of these nucleotides is matched to another, and it takes 30 billion of these base pairs to write the genetic code.
 
58. Hair and fingernails are made out of the same material.
 
59. The brown colour in faeces comes from broken-down red blood cells. Red blood cells are constantly being recycled, and some of the products from their breakdown are secreted into the intestine as part of bile.
 
60. The fish tapeworm is a common intestinal parasite, particularly in the developing world. Its usual length is four to ten metres, and it can live for 20 years.
 
61. Right after your mum and dad’s sperm and egg fused together, you spent about half an hour as a single cell.