Growth & Death
Molecules and Signalling
Protein Synthesis
ATP Production
Electrolytes
Cell Structures
Tissue Structure
Cardiac Output
Cardiac Cycle
Circulation
Special Circulations
Pulmonary Ventilation
Gas Exchange
Regulation of Respiration
Mouth
Stomach
Small Intestine
Large Intestine
Liver
Vitamins
Other
Nephron
Micturition
Regulation
Embryology
Hormones and Regulation
Fetal Physiology
Pregnancy
Components
Synapses
Sensory System
Motor System
Ocular Physiology
Thyroid and Parathyroid Glands
Adrenal Glands
The Pancreas
Hypothalamus and Pituitary
Cells of the Immune System
Innate Immune System
Adaptive Immune System
Immune Responses
Infections
Haematology
The small intestine is an organ located within the gastrointestinal tract. It is approximately 6.5m long in the average person and is where most of the end absorption of nutrients and minerals from food takes place. It lies between the stomach and large intestine and receives bile and pancreatic juices through the pancreatic duct, to aid digestion.
Absorption refers to the movement of nutrients, water and electrolytes from the lumen of the small intestine into the cell, then into the blood. Food components such as carbohydrates, protein and lipids are all digested differently as they require different enzymes in order to be broken down into simpler forms. They are then absorbed in the epithelial cells of the small intestine, where they proceed to enter the bloodstream or lymphatics.
The small intestine contains modifications to aid its function in the absorption of food. The mucosa and submucosa form large folds and contain microvilli, to increase the surface area, enabling for efficient absorption. The small intestine receives secretory products from other abdominal viscera, including bile, pancreatic enzymes and alkaline juice, which are vital for digestion.
In this section, learn more about the physiology of the small intestine- the process of digestion and absorption, and the histology and cellular function of the small intestine.
by Neil Thakrar and Kishan Pankhania
by Sam Barnes
by Emilia O'Connor
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