[Morphology of the liver and duodenum in excluded small intestine]

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 small...

The liver, the largest gland within the human body, is a firm and reddish-brown organ. This wedge-shaped structure weighs approximately 1.5 kg and occupies a significant portion of the right hypochondriac and epigastric regions. It extends more to the right of the body's midline than to the left.
Located under the diaphragm, the liver is almost entirely ensconced within the rib cage, providing it with substantial protection. Except for the superior most bare area, the liver's surface is covered...

The microscopic anatomy of the liver is a complex and intricate system that comprises numerous structural units known as liver lobules, each of which is comparable in size to a sesame seed. These hexagonal structures consist of plates of liver cells or hepatocytes, which are characterized by their versatility and abundance of cellular apparatus like rough and smooth ER, Golgi apparatus, peroxisomes, and mitochondria.
Hepatocytes perform a variety of essential functions. They secrete...

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 C-shape wraps...

The small intestine exhibits a unique histological structure that significantly enhances its function in digestion and nutrient absorption. These structures include circular folds, villi, and various specialized cells that collectively facilitate the digestion of food.
The intestinal lining features transverse folds called circular folds, each housing fingerlike projections known as intestinal villi. These villi are covered by a layer of simple columnar epithelium, also referred to as...

The large intestine, a vital component of the gastrointestinal tract, is structured with four main layers: the mucosa, submucosa, muscularis, and serosa. Each layer performs a distinct role in facilitating the smooth functioning of the large intestine.
The innermost mucosa layer comprises simple columnar epithelium, lamina propria, and muscularis mucosae. This layer is primarily populated with absorptive cells, tasked with water absorption, and goblet cells, responsible for secreting mucus to...