Following on from yesterday's post on getting to know your gut, today we are going to talk about the small intestine and he large intestine.
The name small is actually a little misleading because the small intestine is the longest part of our digestive tract, reaching close to 7 meters in length when stretched out.
In this impressive organ we have the villi and the microvilli which exist along the small intestine to project vital nutrient absorption, which is simple terms means the movement of nutrients from our gut into our circulation.
For example in conditions such as undiagnosed coeliac disease, the person may suffer nutrient deficiencies, this is because the small intestine is flattened or squashed and it doesn't have the surface area that is needed to absorb all the nutrients from food.
Remember I talked about the smoothie mixture that comes from the stomach into the small intestine, well before this can be absorbed, it needs to be broken down further and this is where the the pancreas comes in.
Our pancreas is an organ that feeds into our small intestine, it produces enzymes that help digest our food as well as hormones which help control how much sugar is in our blood.
To further assist with digestion, the liver produces bile acids, which are stored in s small pouch known as the gallbladder. Bile is secreted into the small intestine and helps with the fat digestion and absorption.
In addition to to the enzymes released by our pancreas, the lining of the small intestine also contains enzymes that breakdown food. Lactase for example is an enzyme that breaks down lactose, which is a type of sugar found in milk from animals.
After around 2 to 6 hours, depending on what and how much we have eaten, as well as how our gut muscles are working, the unabsorbed bits, such as dietary fibre will move though the next door (Ileocaecal valve) on into the large intestine.
As the food passes through this door, there is a bouncer there that keeps an eye on who is coming in. If the bouncer starts to notice under-digested food coming in, it closes the door and puts a hold on the upper gut movements.
This is known as the ideal brake and is important feedback system that helps maximise nutrient absorption in the small intestine.
One of the side effects of this is decreased appetite, which explains why when we have diarrhoea, we also lose our appetite.
Unlike the small intestine the large intestine plays a slow and steady game. This is why undigested foods take around 12 to 30 hours to move through it, despite the large intestine being around 4 times shorter than the small intestine.
The large intestine responsibilities are:
1 - HYDRATION - It reabsorbs fluid and electrolytes. During this process the gut contents turn from liquid to solid and the longer your poop to be is in the large intestine, the more water it absorbs and therefore the more solid the poop.
2 - GUT MICROBIOTA - It houses trillions of microbes that make up our GM, even though we have microbes scattered throughout our digestive tract, this is where the main bulk of microbes hang out.
3 - NUTRIENT ABSORPTION - It helps digest things that are indigestible to human enzymes, such as fibre. In doing this our microbes produce messages to our brain that say we are full and we can stop eating, as well as reducing gut inflammation, and much more.
4. WASTE STORAGE & COMPACTOR - The rectum stores and compacts the waste produced by the body, including parts of dead red blood cells which make our poop brown. Once the brain sends the signal to give the rectum the all clear, the accumulated waste is released through the back and final door.
YOU JUST HAD A S##T and hopefully a healthy one :-)