We all know the foods we eat provide our bodies with the energy necessary to live and move. The energy from the foods we digest also helps our bodies regulate and maintain our autonomous systems that run everything from our vision and nervous system to our sympathetic and parasympathetic systems that help control our lungs, blood pressure and heart rate. 

Before the body can use the food we eat to create energy, it first needs to break down our food into a more easily digestible form so our bodies can utilise all the sugars, proteins, fats, vitamins and minerals in the foods we consume. 

As soon as we put something in our mouths and start chewing, our bodies start breaking down the carbohydrates we consume. Our mouths produce an enzyme called salivary amylase, which starts to break down starches and sugars. 

Our stomachs then add gastric juices -including hydrochloric acid – and mix and squeeze food into the small intestine in a process called peristalsis.  

What happens to food when it travels to the small intestine?

Once the mixed up food called chyme enters the small intestine, enzymes are added by the pancreas to break down the carbohydrates into shorter chains. More enzymes are present in the intestinal brush-border membrane including lactase that breaks down lactose and sucrase that breaks down sucrose. These enzymes produce monosaccharides, or simple sugars, such as fructose and glucose that can be absorbed as an energy source to fuel our bodies. A similar breakdown process occurs with protein and fats.

The inner surface or walls of our small intestines are remarkably adapted to absorb the nutrients that pass through them. By creating a series of undulating folds or peaks and troughs called intestinal villi, our small intestine creates a greater surface area for absorption. 

Point of interest - Inflammation of our villi is often a symptom of celiac disease or gluten-sensitive enteropathy. 

The nutrients our bodies have broken down travel across our intestinal villi (shown in the image above), and are then absorbed via absorptive cells and transported to the bloodstream where they are distributed throughout our body. 

References

https://www.ncbi.nlm.nih.gov/books/NBK539845/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4728656/

http://www.vivo.colostate.edu/hbooks/pathphys/digestion/smallgut/absorb_sugars.html