The pancreas functions to secrete the digestive enzymes amylase, lipase, and trypsin, which break down carbohyrdates, lipids, and proteins, respectively. The endocrine role of the pancreas is to secrete the hormones insulin and glucagon, which regulate blood glucose levels.

The function of the appendix is not well classified; it is considered a vestigial structure, which may have once aided in the breakdown of cellulose. The cecum is referred to as the "blind pouch" and is the first part of the ascending colon. The liver functions to manufacture and excrete bile, and removes toxins from the blood. The esophagus transports food that enters the mouth to the stomach.

The liver is the largest organ in the body. It is roughly triangular, with a smooth brown surface. The liver receives arterial blood through the hepatic artery, venous blood leaves through the hepatic vein, and a third circulatory system, the portal, receives nutrient-rich blood from the gastro-intestinal tract. The liver works to detoxify substances in this blood.

The gallbladder stores bile, which is formed in the liver. Bile is used to digest fatty foods. The pancreas is wedge-shaped and secretes digestive enzymes and hormones. The parotid gland is located inferior and anterior to the ear. This gland secretes saliva. The adenoids are prominences of lymphoid tissue located in the nasopharynx.

During the course of development the ascending colon is pushed against the posterior wall of the abdomen to become secondarily retroperitoneal. Other retroperitoneal organs include the descending colon, kidneys, adrenals, esophagus, ureters, pancreas (except tail), the second and third segments of the duodenum, the aorta/inferior vena cava, and the rectum.

The spleen, transverse colon, and stomach are all intraperitoneal organs (located within the abdominal cavity and wrapped in peritoneum) .

Calyces are horn-shaped tubes that carry urine to the renal pelvis. The medulla is the inner part of the kidney that determines how concentrated urine is; the loop of Henle dips deep into the medulla to use the high osmolarity to drive the concentration of fluid in the renal tubule. The ureter is the muscular tube that connects the kidneys to the bladder. The cortex is where the blood is filtered in the glomerular capillaries.

The epithelia of the small and large intestine form glands called crypts located between villi. The crypts are a collection of cells including columnar secreting cells, goblet cells and stem cells. Stem cells are cells that are capable of self-renewal. They are not located in the muscular layer of the intestine or in any layer of the stomach or esophagus.

In the urinary system, the kidneys remove wastes from the blood and produce urine. The ureters are responsible for carrying the urine to be stored in the bladder. The urethra is responsible for draining urine from the bladder and conveying it out of the body.

The fundus is the protruding upper left portion of the stomach. In the event that a great deal of food enters the stomach, the fundus will allow excess food to be stored until it is ready to be digested in the small intestine.

The body of the stomach is where most physical digestion occurs and some chemical digestion takes place. The cardia is the region joining the esophagus to the stomach and is characterized by the cardiac sphincter. The pylorus joins the stomach to the small intestine and contains the pyloric sphincter.

The esophagus enters the abdomen by piercing the diaphragm at the T10 vertebrae level. The esophagus is a muscular hollow tube that connects the pharynx with the stomach. It runs behind the trachea and heart and is located in front of the spine.

The cecum is the first part of the large intestine. After traveling through the cecum, digested material travels up the ascending colon, past the hepatic flexure, through the transverse colon, past the splenic flexure, down the descending colon, and finally through the sigmoid colon.

Retroperitoneal organs include the following: esophagus, adrenal glands, aorta/inferior vena cava, second and third parts of the duodenum, pancreas (except the tail), ureters, colon (ascending and descending portions), the kidneys, and the rectum.

The retroperitoneal space is an anatomical space within the abdomen but behind the peritoneum. Retroperitoneal organs should have peitoneum only at the anterior surface. These organs are not suspended by mesentery.