THE CURVACEOUS SMALL INTESTINE AND BETTER HEALTH
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Your small intestine is a curvaceous tube that starts at your stomach and ends at your large intestine. It’s coiled up and packed tight inside you right under your stomach. If you stretched it all out, it would measure around 20 feet long. To give you a comparison, an adult giraffe grows to be about 18 feet tall.
Surface Area Is The Name of the Game
Why is the small intestine so long?
Surface area.
The job of the small intestine is to absorb nutrients from our food across its lining.
And surface area of that gut lining is critical to ensure enough nutrients are absorbed.
Without sufficient surface area, you would quickly become malnourished or even starve regardless of how much food you eat.
Without absorbing enough proteins across the gut lining, for example, your body doesn’t get enough of the amino acids it needs for hair growth or for neurotransmitter production to regulate mood.
Yes, surface area is that serious.
The human small intestine is designed for maximum surface area, not just by its length, but also by the tiny, finger-like projections that line the entire length of the small intestine. So rather than being a long smooth tube, the inside of the tube has these dips and curves which, you guessed it, greatly increases the surface area.
Villi, Crypts, and Brush Border
Villi, that is the name for these projections. Villus is the singular of the term and villi is the plural.
Take a look at this image taken under a microscope of the intestinal wall. Do you see the villi?
And those deep grooves between all the villi are called the Crypts of Lieberkühn. If that wasn’t enough, there are tiny hair-like projections on the villi too that again, you guessed it, increases the surface area, and those hairs are called microvilli or brush border.
According to a 2014 study, the total surface area of the human adult gut mucosa, that is both the small and large intestines, is about half the size of a badminton court.
Villous atrophy, crypt hyperplasia, and blunted brush border are common factors in disease states. There are many potential causes for these conditions including chronic exposure to food intolerances, gut pathogens, Celiac disease, and even some medications. In 2013, the FDA issued a warning that the blood pressure medication olmesartan medoxomil (marketed as Benicar, Benicar HCT, Azor, Tribenzor, and generics) can lead to villous atrophy combined with diarrhea and weight loss.
Nutrient Absorption
Each villus has a network of blood capillaries as well as lymphatic capillaries (lacteals) close to its surface. The epithelial cells of the gut lining transport the nutrients across its surface and the nutrients are then transported via the blood and lymphatic vessels around the body. The majority of nutrients (proteins and carbohydrates) are transported via the blood vessels and the lymph system is responsible for the fats.
It is all those dips and curves that together so beautifully amplify the surface area of the small intestine all along its length, all in the name of absorption.
Magnificent, isn’t it.
Dana Trentini
One day my body suddenly broke from hypothyroidism. I clawed my way back to health by devouring the scientific literature. You see, I was once the team leader of an Ivy League professor’s research team with no clue then that those skills would one day save my life and that my site Hypothyroid Mom would spread across the internet like lightening. And then came the day to share all my other precious health nuggets and Yes! Healthier was born.