Test Your Knowledge of the Gastrointestinal System

Study Notes

The gastrointestinal tract consists of a long tube that runs from the mouth to the anus.
The main job of the gastrointestinal system is ingestion - taking in food, digestion - breaking it down into nutrients, absorption - pulling these nutrients into the bloodstream, and finally, excretion - getting rid of waste.
All along the gastrointestinal tract, there are four layers of tissue that line the walls.
The outermost layer is either the adventitia, a thick fibrous connective tissue, or the serosa, a slippery serous membrane.
Next is the muscularis externa, a smooth muscle layer, which contracts automatically, without you even having to think about it.
The submucosa, which consists of a dense layer of tissue, contains blood vessels, lymphatics, and nerves.
Buried in the submucosa, there’s a second plexus, the submucous plexus, also called as Meissner’s plexus, which is responsible for helping to coordinate muscle contraction and relaxation.
The stomach is a large organ located in the upper part of the small intestine.
The stomach's main job is to churn and digest food so that nutrients can be absorbed.
The pancreas is a long, skinny gland located near the duodenum and it secretes digestive enzymes that help to break down fat.
The small intestine has three parts: the duodenum, the jejunum, and the ileum.
The small intestine can be as long as 10.5 meters or about 35 feet, and it has many tiny ridges and grooves.
Each villus is covered in tiny microvilli and this gives the small intestines plenty of surface area to absorb nutrients.
The liver, gallbladder, and pancreas work together to help the small intestine absorb nutrients. The gallbladder squeezes bile from the liver and the pancreas secretes digestive enzymes that help to break down fat.
The gastrointestinal (GI) tract is a long, twisting tube that starts at the stomach and ends at the rectum.
The GI tract is responsible for breaking down food into nutrients that can be absorbed into the bloodstream.
The small intestine is responsible for absorbing nutrients from the food, while the large intestine absorbs waste products.
The gut microbiome helps to colonize the large intestine and helps to break down food.
Chyme that makes it past the small intestine and into the large intestine is met by trillions of bacteria, which are collectively called the gut microbiome.