Digestion
Once a snake, like the rubber boa, captures its prey, it pushes it past the mouth with a movable skull. It uses a "walking" motion to force it down the throat. Unlike humans, snake saliva doesn't aid in digestion. Instead, it just acts as a lubricant for the prey to slide further in the animal.
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After the esophagus, the food enters the snakes tube-like stomach that extends until the pylorus. The pylorus is a valve that serves as the entrance of the small intestine. After the small and large intestine, the food reaches the cloaca. All the while, nutrients and water has been leeched out of the food and absorbed into the intestines (Mader Gastrointestial Tract).
Here we see the tail end of the snake. "Li" is the large intestine; "Cl" is the cloaca; "V" is the vent; the red arrow points to the scent gland; the green points to the vestigial anal spurs, and the yellow points to the hemi-penises. (Mader Gastrointestial Tract)
Studying the thermoregulation of digestion of rubber boas, we see that they have an optimal temperature for digestion and passing waste. After feeding, a rubber boa's digestive rate is low at lower temperatures and increases as the temperature increases. However, there is a threshold temperature, so when the environment is at higher temperatures, the digestive rate slows.
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As the body temperature (Tb) of a rubber boa increases, digestive enzymes are secreted at a higher rate leading to a higher digestive rate. But, at even higher temperatures, Hydrogen Chloride levels decrease causing the pH level to be higher than the optimal level for pepsin activity. This can explain the lower digestive rates at the higher temperatures.
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Some researchers used the passage rate of snakes to indicate the digestive rate. Looking at the graph to the right, we see that the passage rate has a different optimal temperature. This is likely due to the several steps needed for passage to occur, all with their own optimal temperature. Metabolic rate seems to play a rolw in passage rate more than in digestive rate (Dorcas Thermal Biology)
(Dorcas Thermal Biology)