Digestion, Absorption, and Metabolism of Macronutrients

By: Jessica Hudson

Remember: Macronutrients are carbohydrate, protein, and fat.

Carbohydrate

To begin, carbohydrates are broken down into glucose. The digestion process begins in the mouth where salvia enzymes begin breaking the food apart. After the food enters the stomach, it is somewhat broken down into chyme. Now the chyme moves to the small intestine where it is broken down further. The carbohydrates that were not absorbed in the small intestine move to the large intestine where it will be further broken down. 

Metabolism of Carbohydrate

After food is consumed, glucose levels in the human body rise. If the glucose level appears to be high, the pancreas releases insulin to the blood stream in order to move glucose to different organs for  later use. 

Protein

To begin the process of digesting protein, food is chewed in the mouth and then swallowed. When the food reaches the stomach acids mix together to create pepsin. Pepsin is the name of the enzyme that breaks proteins down into amino acids (The Digestive System, n.d.). What is not absorbed moves into the large intestine, and finds its way out through the anus.

Metabolism of Protein

Protein breaks down into amino acids. Amino acids are then released into the blood stream. Once these amino acids have reached the blood stream they are further broken down and distributed to parts of the body in need. 

Fats

The digestion process for fats begin after they are chewed and find their way into the stomach through the esophagus. Once they arrive in the stomach they begin separating from the water molecules and move into the small intestine. The gallbladder then releases bile into the small intestine to split the fat molecules. Fats are then absorbed as needed by cells (Sizer and Whitney, 2013). 

Metabolism of Fats

After fats have been absorbed into the blood stream, they are distributed to the tissues or they will be used to produce energy.

Reference

Photos Retrieved from Google.

The Digestive System.  YouTube.  Retrieved from http://www.youtube.com/watch?v=s06XzaKqELk 

Sizer, F. & Whitney, E. (2013).  Nutrition: Concepts and Controversies (13th ed.).  Mason, OH: Cengage Learning.