Fantastic Voyage Through the Body The man is eating a hamburger and French fries while drinking a root beer. He is mechanically separating the food into smaller units, and then he is swallowing it. For this exercise, it is important to realize that there are four different types of material that will be absorbed by the body and that they are all absorbed differently. These are fiber from the leafy greens on the hamburger, fats from the hamburger and French fries, proteins from the hamburger, and carbohydrates in many forms which make up the bulk of the meal. They start off in a common area, but they end up going through different processes to either leave or remain in the body.

The first part of the journey is taken by all of the nutrition types. The man bites off a chunk of burger or fires, or drinks a swallow of root beer, and this is processed first in the mouth. The teeth tear and then chew the food to get it into small enough portions that it can be sent through the second part of the journey. After exiting the mouth, all of the food travels down the esophagus via peristaltic action to the stomach. Here the different types of food part ways.

Fiber is probably the least complex of all of the processes because most of it passes, without molestation, through the digestive tract without any absorption or other interruption. The fiber enters the stomach which does little to break it down other than to further decrease the size of the mass. It then travels down through the small intestine and the colon. It is excreted as solid waste (Robinson, 2011). The fiber actually plays another role as it is excreted...

Protein must be broken down before it can be absorbed, but that cannot happen in the mastication process (Andrews, 2011). When protein enters the stomach it is in small chunks that must somehow be unraveled so that they can be transported through the cell membranes where they will be utilized. In the stomach specialized cells secrete acid which unravels the rope that is protein from a large strand of any protein molecules into smaller single strands (Andrews, 2011). The process in the stomach, denaturation, occurs as stomach contractions, enzymes and acid work to break down the protein into manageable chunks. When the protein enters the small intestine, the pancreas and gall bladder add protease compounds that further break the molecules into amino acids. The cells in the small intestine also provide proteases (Andrews, 2011). The amino acids are absorbed by the intestinal cell walls as individual dipeptides and tripeptides, then they are further separated into individual amino acids. These amino acids are then either used by the intestinal cells to create needed proteins within the body, or they are sent to the liver for the same function. The proteins are then broken down by muscle fibers for energy.
The third substance is the fat that the meal includes. Fats are probably the most difficult substances for the body to absorb, and they are broken down through complex processes. "Dietary fats are large, complex…