gastrointestinal (GI) tract

Examples of gastrointestinal (GI) tract in the following topics:

• X-Ray Studies of the GI Tract

  • Upper GI series, also upper gastrointestinal (GI) tract radiography, is a radiologic examination of the upper gastrointestinal tract.
  • Upper GI series, also known as upper gastrointestinal (GI) tract radiography, is a radiologic examination of the upper gastrointestinal tract .
  • When the patient needs to undertake an upper GI, he or she may be asked to fast on the previous day.
  • The upper GI tract consists of the esophagus, stomach, and duodenum.
  • Describe the process and purpose of taking X-rays of the GI tract

• Mucosa

  • The mucosa, composed of simple epithelium cells, is the innermost layer of the gastrointestinal (GI) tract.
  • It is the absorptive and secretory layer of the GI tract.
  • The GI tract is composed of four layers.
  • The mucosae (singular: mucosa) are highly specialized in each organ of the gastrointestinal tract in order to deal with different digestive tract conditions.
  • Describe the structure and function of the mucosa of the GI tract

• Muscularis

  • The muscularis is responsible for the segmental contractions and peristaltic movements in the gastrointestinal (GI) tract.
  • The gastrointestinal (GI) tract is composed of four layers of tissue, known as tunics.
  • The muscularis externa is responsible for segmental contractions and peristaltic movement in the GI tract.
  • These muscles cause food to move and churn together with digestive enzymes down the GI tract.
  • Alone among the GI tract, the stomach has a third layer of muscularis externa.

• Divisions of the Autonomic Nervous System

  • Example functions of the SNS include diverting blood flow away from the gastrointestinal (GI) tract and increasing heart rate.
  • Example functions of the PSNS include dilating the blood vessels that lead to the GI tract and stimulating salivary gland secretion.
  • Some functions of the SNS include diverting blood flow away from the gastrointestinal (GI) tract and skin via vasoconstriction, enhancing blood flow to skeletal muscles and the lungs, dilating the bronchioles of the lung to allow for greater oxygen exchange, and increasing heart rate.
  • The PSNS typically functions in contrast to the SNS by dilating the blood vessels leading to the GI tract, causing constriction of the pupil and contraction of the ciliary muscle to the lens to enable closer vision, and stimulating salivary gland secretion, in keeping with the rest and digest functions.

• Organs of the Digestive System

  • Throughout our gastrointestinal (GI) tract, each organ serves a specific purpose to bring our food from the plate to a digestible substance from which nutrients can be extracted.
  • The major organs within our digestive system can be split into two major segments of this tube: the upper gastrointestinal tract, and the lower gastrointestinal tract.
  • The upper gastrointestinal, or GI, tract is made up of three main parts:
  • The bolus gets swallowed, and begins its journey through the upper gastrointestinal tract.
  • The stomach is a muscular, hollow bag that is an important part of the upper GI tract.

• Digestive Systems

  • The digestive system consists of a group of organs that form a closed tube-like structure called the gastrointestinal tract (GI tract) or the alimentary canal .
  • For convenience, the GI tract is divided into upper GI tract and lower GI tract.
  • The organs that make up the GI tract include the mouth, the esophagus, the stomach, the small intestine, and the large intestine.
  • There are also several accessory organs that secrete various enzymes into the GI tract.

• Anatomy of the Digestive System

  • The upper gastrointestinal tract consists of the esophagus, stomach, and duodenum.
  • The lower gastrointestinal tract includes most of the small intestine and all of the large intestine.
  • It contains the plicae circulares and villi to increase the surface area of that part of the GI tract.
  • The ligament of Treitz is sometimes used to divide the upper and lower GI tracts.
  • This image shows the position of the small intestine in the gastrointestinal tract.

• Gastrointestinal Reflex Pathways

  • The digestive system functions via a system of long reflexes, short reflexes, and extrinsic reflexes from gastrointestinal (GI) peptides working together.
  • The gastrocolic reflex is the physiological reflex controlling the motility, or peristalsis, of the gastrointestinal tract.
  • GI peptides are signal molecules that are released into the blood by the GI cells themselves.
  • They act on a variety of tissues including the brain, digestive accessory organs, and the GI tract.
  • The gastrocolic reflex is one of a number of physiological reflexes controlling the motility, or peristalsis, of the gastrointestinal tract.

• Submucosa

  • The GI tract is composed of four layers.
  • The muscularis in the stomach differs from that of other GI organs in that it has three layers of muscle instead of two.
  • In the gastrointestinal tract, the submucosa is the layer of dense irregular connective tissue or loose connective tissue that supports the mucosa.

• Adrenergic Neurons and Receptors

  • All three are linked to Gs proteins (although β2 also couples to Gi), which in turn are linked to adenylate cyclase.
  • α2, on the other hand, couples to Gi, which causes a decrease of cAMP activity, that results in smooth muscle contraction.
  • Common (or still unspecified) effects include: vasoconstriction of cardiac arteries (coronary artery), vasoconstriction of veins, and decreased motility of smooth muscle in the gastrointestinal tract.
  • It causes vasoconstriction in many blood vessels, including those of the skin, gastrointestinal system, kidney (renal artery), and brain.
  • Smooths muscle relaxation, e.g., in bronchi and the GI tract (decreased motility).