There was this yucky joke about the human digestive system: A guy decided to go on diet in which he eats only peanuts. After three days, he churned out...peanut butter! What happened to the peanut inside his body?
Let's begin by meditating on the length of 9 meters. My room is 3 meters high so that is the height of a 3-storey house. This is how long a digestive tract is, all coiled up from the mouth to the anus.
To be acquainted with the digestive tract, you should know its other identities such as digestive tube. Biology textbooks refer to it as the alimentary canal, alimentary tract or gastrointestinal tract. Since I am lazy to write with my hand, I prefer the short form GI tract.
Connected to the brain electrochemically by sophisticated autonomic nervous system,the digestive tract contracts and expands in a worm like manner called peristalsis. The rate of peristalsis has to be just right: Too much, diarrhea ; too little or none, constipation.
Assuming the peanut is properly masticated, peristalsis pushes it along the digestive tract in the form of a soft mass called bolus. So our peanut bolus meets the other members of the digestive tract: esophagus, stomach, small intestine and large intestine.
I heard about ancient Romans' legendary gluttony. They ate to the point of explosion, poke a finger into the mouth to vomit then return to gorge on more food. Why doesn't food flow backwards and overflow at the rate these gentlemen indulged?
It is due to the presence of sphincteric muscles. Not sure what is sphincteric muscle? When you wipe your...ahem...butt, feel for the muscles radiating from the anus, this is an example of sphincteric muscle which can also be found between the esophagus and stomach, stomach and duodenum, small intestine and large intestine and rectum.
These strong muscles contract to make food pass in ONE direction, which explains why the Romans had to torture themselves to force food go the other direction. I wish I could interview these Romans whether they had constipation for abusing their intestinal tract.
Anyways, back to our peanut. Normally it is processed between 24 - 72 hours before exiting, definitely NOT as peanut butter.
The Human Digestive System
"Journey of a peanut through the digestive tract."