Five Resections of the Alimentary Canal

The human digestive system is an intricate and essential network for nutrient absorption and waste elimination. It encompasses the gastrointestinal (GI) tract and several accessory organs.
Here's a detailed walkthrough of this complex system:

The large intestine is divided into three main regions: the cecum, colon, and rectum. Extending from the ileocecal valve to the anus, it frames the small intestine on three sides.
The ileocecal sphincter, a mucous membrane fold, guards the opening from the ileum to the large intestine. This valve permits material from the small intestine to pass into the large intestine. Attached to the ileocecal valve is the cecum. This small pouch, approximately 6 cm long, has a twisted, coiled tube known as...

The esophagus, a muscular conduit linking the pharynx and stomach, measures roughly 10 inches (25.4 cm) and sits behind the trachea. It remains collapsed when not swallowing. The esophagus follows a predominantly straight path through the thoracic mediastinum and enters the abdominal cavity through a diaphragmatic opening known as the esophageal hiatus.
The movement of edibles from the pharynx into the esophagus is facilitated by the upper esophageal sphincter, which is formed primarily by the...

Although digestion of proteins, carbohydrates, and lipids may begin in the stomach, it is completed in the intestine. The absorption of nutrients, water, and electrolytes from food and drink also occurs in the intestine. The intestines can be divided into two structurally distinct organs—the small and large intestines.
Small Intestines
The small intestine is an ~7 meter-long tube with an inner diameter of just 2.5 cm. Since most nutrients are absorbed here, the inner lining of the...

The GI tract, from beginning to end, is made up of four continuous tissue layers that adjust their structure according to their specific roles. These layers, from innermost to outermost, are known as the mucosa, submucosa, muscularis, and serosa, which are continuous with the mesentery.
The mucosa is sometimes called a mucous membrane due to its mucus-secreting features. This membrane is composed of epithelium, which directly interacts with ingested substances, and the lamina propria, a layer...

The small intestine is primarily responsible for digestion and nutrient absorption. It spans from the pyloric sphincter to the ileocecal valve and connects to the large intestine.
The small intestine is divided into three main sections - the duodenum, jejunum, and ileum. The duodenum, approximately 25 cm long, is nearest the stomach. It acts as a 'mixing bowl,' where chyme (partially digested food) blends with digestive enzymes from the pancreas and liver. The duodenum's unique...