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...

Intestinal obstruction triggers a series of physiological responses, starting with gas and fluid accumulation in the bowel segment proximal to the obstruction, leading to distension. This distended intestine compresses the diaphragm, hindering lung expansion and potentially leading to reduced respiratory effort, atelectasis, and pneumonia.To overcome the blockage, the gut intensifies contractions, causing colicky abdominal pain, nausea, and vomiting, which reduces fluid and food intake and...

The coronary arteries, originating from the ascending aorta, bifurcate from two sinuses located within the ascending aorta. Positioned just above the aortic semilunar valve, these sinuses house essential aortic baroreceptors and chemoreceptors, crucial for maintaining cardiac function. The left coronary artery and the right coronary artery branch off from the left posterior and anterior aortic sinuses, respectively.
Encircling the heart, the coronary arteries form a ring-like structure before...

A hiatal hernia is the abnormal protrusion of the stomach or other abdominal organs through the esophageal hiatus of the diaphragm into the thoracic cavity.Normally, the gastroesophageal junction (GEJ) lies below the diaphragm and is supported by the phrenoesophageal membrane, the diaphragmatic crura, and connective tissues. Weakening of these structures—due to aging, congenital defects like a short esophagus, or increased intra-abdominal pressure from coughing, obesity, pregnancy, or heavy...

Intestinal obstruction is a partial or complete blockage of the small or large intestine that disrupts the normal flow of intestinal contents through the lumen. This interruption impairs digestion, absorption, and fluid balance, and may lead to serious complications if not treated promptly.Mechanical ObstructionMechanical obstruction occurs when a physical blockage prevents intestinal contents from passing, arising from within the lumen or the bowel wall, or from external compression.Adhesions,...

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...