G'day Team,

After chatting with a patient about how his esophagus hurt for half an hour, then realizing he meant his trachea, I thought I'd throw together a post on some common misunderstanding and small unknown facts about human anatomy and physiology.

You don't breath through your esophagus

Alrighty, so it all starts here. There are two pipes that travel from the back of your throat down to your body. Down the front we have the trachea, the pipe we breathe from. The trachea is hard and surrounded by cartilage. Behind the trachea, we have a muscular tube which pushes down food, called the esophagus.

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You can't change your blood pH

With all the fad diets floating around these days it was only a matter of time till someone said they were going to target the blood. Fortunately for us, our body already has an ingenious system for controlling the pH of our blood. For our body to function normally we have to maintain a pH of between 7.35 and 7.45. Now we don't do this just by fighting against the foods we eat, we actually have a smart "buffer" system which 'absorbs' the influence any molecules which may alter our blood pH.

Without getting into the science of it too much, we use bicarbonate (from the CO2 that our cells produce burning oxygen) in order to buffer our blood. The equation below can work in either direction and as such when too much acid enters our blood it's pushed to create a blood and visa versa for a base.

H₂CO₃ <-> HCO₃^- + H⁺

Your brain doesn't control all your movements

While our brain is probably the most important organ when it comes to controlling the movements we're aware of, our bodies movements often simply run on automatic too. We've all heard of reflexes, but did you know these movements are controlled in our spinal cord, not our brain.

A reflex occurs when input into a nerve elicits a response that we do not actively control. Now we all know about the large reflexes, like withdrawing from heat or pain, but reflexes control a lot of other small actions in our body too. These include digestive movements, regulation of blood pressure and balance. A lot of these are controlled in the spine, but in the stomach, they're also controlled in things like the myenteric plexus.

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Deoxygenated blood isn't blue

At some point about 15 years ago someone decided to have the genius idea of referring to oxygenated blood as red and deoxygenated blood as blue.

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Now as you can see, blood is red. Blood with oxygen in it is a little brighter, but no blood is blue! This misconception may have come from the green-blue appearance of veins, a color they obtain because this is the wavelength that will filter through the skin.

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Your ear and nose are connected from the inside

Ever wonder why yawning corrects the pressure in your ear when you're flying! The only reason that pressure builds up in the first place is that there's a small sealed off section behind the ear-drum (tympanic membrane). However, a narrow tube, called the eustachian tube, connects this area to the back of the internal nasal cavity near the throat, known as the nasopharynx.

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Now, this tube is much shorter and wider in children, which explains why they're so much more prone to ear infections, as bacteria can climb from the nose and mouth to the ear.

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20/20 vision means you can see what a normal person can see

When we measure vision, we measure it using a simple bit of shorthand.

X/Y

Where X feet is the distance at which you can see, what a normal person can see at Y feet. 20/20 vision means you can see at 20m what a normal person can see at 20m. 10/20 means you have to be 10 feet away and using this we can say that 4/20 vision is very bad, but 20/10 vision is much better than normal...

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You don't have 5 senses

While we often hear about our five senses (and the mysterious 6th sense) it's not regularly recognized that we already have a slew of other senses beyond the normal five. These include senses for things such as thirst, balance, hunger, proprioception (knowing where our body parts are without looking) and spacial-perception (where we are in a room for example). Now, these extra senses aren't conveniently linked with a part of our body, like seeing and hearing may be, but they are none the less vital to our everyday lives.

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The penis doesn't get hard by squeezing a muscle

Sooooo, how many times have I heard people tell me that a penis gets hard because the muscles contract! No, no no! While it is true the penis is extremely muscular, and contraction of muscles allows us to somewhat control the movement of the penis, this is not the primary mechanism for an erection. The reason that an erection occurs is because it becomes engorged with blood. As we become aroused the blood flow to our penis (specifically the corpus cavernosum) increases and the veins which drain it close off, meaning it gets blown up like a balloon!

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Your tongue doesn't have different taste sections

Now we all learned this in primary school! Different parts of our tongue taste different things... unfortunately it's all bulls@*#. Now this all stemmed from a misunderstanding of a paper published in 1901, and the myth has floated around for over 100 years now!

Adult teeth sit in your skull!

Now, this is something even I hadn't realized until someone told me! Those teeth that push out our baby teeth actually sit up in our skull before they come through! Take a look

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Thanks

Thanks for reading and I hope everyone learned something!

-tfc

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