The human body is pretty amazing. It’s capable of extreme feats of endurance, strength, and flexibility – but these are just the start of its incredible abilities. Like an iceberg, the body’s true magnificence only becomes apparent when you take a peek under the surface. To take your appreciation for your body to new heights (or rather, new depths), we’ve got six mind-blowing things that you didn’t know about your body.
1. Your brain has about 100 billion neurons
Neurons play an incredibly important role in the human body, turning the sensory inputs we receive from the external world into motor commands for our muscles. The reason why you jerk your hand back when touching a hot stove, or why you hop around in agony after stepping on a Lego brick, is because neurons send signals from your hand (or sore foot) to your central nervous system (CNS). Your CNS then sends signals to your muscles, which pull your affected limb away from the source of the pain quicker than you can say “bloody hell”.
The human brain is estimated to contain 100 billion neurons – which happens to be about the same number of stars in the Milky Way galaxy. In fact, it is this high density of neurons that gives the brain its characteristic grey color. When you consider all the complex things the brain is capable of – such as higher order thinking, conceptualization, and even forming the idea of the “self” – it’s not surprising that so many neurons are needed to perform these complicated tasks.
2. Babies are born with 300 bones, but adult skeletons only have 206 bones
Babies are born with more cartilage than bone. As they mature, this cartilage is fused together and turned to bone. A newborn baby’s skull consists of multiple (partially) bony segments that eventually join together as it ages. Until they fully harden (ossify), the baby has “soft spots” on its head that should not be pressed.
3. You can’t breathe and swallow at the same time
Go on, try it. Human adults can’t breathe and swallow at the same time due to the placement of their voice box. However, since the voice box doesn’t drop until about nine months of age, infants are able to breathe and swallow while feeding.
4. Laid end-to-end, an adult’s blood vessels could circle Earth’s equator four times
If you laid out all the blood vessels in your body in a straight line, that line would be 100,000 miles long – enough to circle the Earth’s equator four times. How crazy is that?
5. Salivary glands can produce up to 1.5L of saliva a day
Of course, this number may increase radically if you open your freezer to see a tub of salted caramel ice cream staring seductively back at you. But on an average day, you can expect your salivary glands to produce between two to six cups of saliva.
As disgusting as it is to imagine, all this saliva must be swallowed. If you didn’t swallow at all, your lungs would quickly fill with oral and nasal secretions and you’d die within a few days.
And since the days of spitting into spittoons are long behind us, the only socially acceptable prospect left is to swallow. Luckily the autonomic nervous system (ANS) largely takes care of this for us – so we don’t have to go around consciously swallowing a liter of saliva every day.
6. Your penis is not a muscle
Although it can grow in size and strength, the penis is not a muscle. Instead, the penis is largely made up of spongy tissue known as the corpus callosum. When you get aroused, your parasympathetic nervous system (PSNS) kicks in and the arteries in your penis dilate (open). As a result, more blood flows into the penis – and it’s this increased blood flow that results in an erection.