National-International Giraffe Cardiovascular Neatness Month

Giraffes

After a long hiatus, NAOTW is back and it couldn't be better timing because January is National-International Giraffe Cardiovascular Neatness Month.  How neat is that!  Giraffe's (pronounced "gi"-like gyroscope and "raffe" like Raffi of Baby Beluga fame) have one of the neatest cardiovascular systems in the animal kingdom!

Raffi

Let's start with the neck. It long, it's strong, and it's down to get it's friction on. Giraffes long necks, which have as many cervical vertebrae as humans and other mammals (7) but are just longer (10-11 inches), are useful for a butt-ton of things such as:

*reaching wicked high branches to feed on acacia leaves and seedpods (which are highly nutritious but also are toxic to other animals..yuckers)

*fighting with other giraffe's by using their head-neck combo as a medieval flail weapon (longer necks increase the torque they can exert on their "genemies"--Giraffe-enemies if you will.  VIDEO HERE

*AND long giraffe necks provide ample real estate for "gickies"---or giraffe hickies---and other related activities of ungulate foreplay. 
 

Because their necks are so g-darn long their hearts must generate enough arterial blood pressure, nearly 300mmhg, to overcome the gravitational and hydrostatic pressure exerted on the heart by the height of the column of blood in neck arteries. So you're probably thinking:

"The left ventricular and interventricular walls in the heart are probably really enlarged in order to produce such a systemic blood pressure." And you would be wrong. I mean right.  Very fucking right.  NERD ALERT



Giraffe heart - the left ventricle walls (above) are nearly 8cm thick 



You're probably also thinking, why don't giraffes get super duper dizzy when they bend their necks down to drink.  It's because that neck, underneath all those gickies, has a complex pressure regulation system called the rete mirabile that prevents excess blood flow to the brain when the giraffe drinks or dips it's head low to do lines of "gocaine" or giraffe cocaine. "Wait a minute, Max," a reasonably headed person might say, "giraffes? cocaine? gocaine? no way Gose." Well, giraffes have one of the shortest sleep requirements of any mammal, between 20 minutes and two hours in a 24 hour period.  Now I say, give me a more plausible explanation for their short sleep requirement other than excessive gocaine use.

Then, since giraffes have the blood pressure of an obese person from Kansas who does nothing but work hard on her foopa game, smoke 2 packs of heaters a day, gurgle ground beef, and hold Chipotle burritos as a security blankets, you'd expect them to stroke out and the pressure exerted on the lower vessels to push fluid though the capillary walls like this lady:



Visual representation of giraffe blood pressure in a human from Kansas

Giraffes, though, have a tight sheath of thick skin over their lower limbs which maintains high extravascular pressure just like a Iceman's G-suit in Top Gun.

Hope you learned a lot about giraffes!  How neat are they!