Gastrointestinal Tract Functions

The process involving sequential relaxations and contractions of muscles, moving food through the gastrointestinal tract.

The lower esophageal sphincter's function is to prevent food from going back up into the esophagus.

A bag-like structure that mixes and stores food, secretes digestive juices, and propels partially digested food into the duodenum.

The vagus nerve stimulates gastric secretions and motility.

Gastrin and motilin are hormones that stimulate the stomach's emptying, while secretin and cholecystokinin slow down the process.

Chief cells secrete pepsinogen, which is converted to pepsin in the acidic environment created by hydrochloric acid.

These glands secrete intrinsic factor, which is needed for vitamin B12 absorption, and hydrochloric acid, which dissolves food fibers, kills microorganisms, and activates the enzyme pepsin.

The process of chewing and salivation, where α-amylase in saliva initiates carbohydrate digestion.

The process by which chyme (partially digested food) is mixed and propelled along the intestinal tract by alternating contractions of circular and longitudinal muscles.

The inhibitory reflex triggered when the ileum is distended, slowing down gastric emptying.

The reflex that inhibits intestinal motility when one segment is overdistended, preventing overstretching.

The reflex that increases intestinal motility when gastric motility increases, preparing for the incoming food.

The reflex triggered by distention of the ileum with chyme, causing a mass movement of feces towards the rectum.

The process of expelling feces from the rectum, triggered by rectal distension.

The largest organ in the body, responsible for various functions, including digestion, metabolism, and detoxification.

The cephalic phase is triggered by the anticipation of food, taste, or smell, while the gastric phase is initiated by the presence of food in the stomach, and the intestinal phase is activated by the arrival of chyme in the small intestine.

The duodenum receives chyme from the stomach and triggers the liver to release bile and the pancreas to secrete enzymes and alkaline fluids.

These projections increase the surface area of the small intestine, aiding in the absorption of nutrients.

The small intestine is the primary site for digestion and absorption of ingested nutrients and water.

These enzymes aid in the breakdown of carbohydrates, proteins, and fats within the small intestine.

The peritoneum, a double-layered membrane, surrounds the abdominal organs, providing support and protection.

The superior mesenteric artery supplies primary blood flow to the small intestine, ensuring nutrient delivery and waste removal.

Bile, produced by the liver, aids in the digestion and absorption of fats. It also neutralizes acidic chyme, facilitating protein, carbohydrate, and sugar digestion by pancreatic enzymes.

The primary bile acids, synthesized from cholesterol by the hepatocytes, are conjugated to form bile salts. Secondary bile acids are formed from bile salt deconjugation by bacteria in the intestinal lumen.

Bile salts and acids are absorbed from the terminal ileum and returned to the liver.

Bilirubin, a breakdown product of aged red blood cells, is made water-soluble by hepatocytes and excreted in bile.

The liver makes fats from protein and carbohydrates (glycerol, fatty acids, phospholipids, and cholesterol) and converts dietary triglycerides into glycerol and fatty acids.

The liver requires essential amino acids to make albumin, globulin, serum enzymes, and can convert amino acids to carbohydrates by removing ammonia.

The liver can release glucose, store carbohydrates as glycogen, or convert carbohydrates to fat.

The liver detoxifies substances from the body, including harmful chemicals, drugs, and waste products.

The gallbladder, located beneath the liver, stores bile between meals and releases it when chyme triggers the release of cholecystokinin.

Bile is released from the gallbladder through the cystic duct and common bile duct into the duodenum to help digest fats.

The pancreas produces enzymes such as trypsin, chymotrypsin, and lipase that break down proteins, carbohydrates, and fats, respectively.

The hormone secretin stimulates the pancreas to release alkaline fluid, which neutralizes the acidic chyme coming from the stomach.

Cholecystokinin and acetylcholine stimulate the pancreas to release digestive enzymes, specifically trypsin, chymotrypsin, and lipase.

The pancreas produces insulin and glucagon, which regulate blood sugar levels.

Elevated levels of serum amylase indicate pancreatic dysfunction, as this enzyme is vital for carbohydrate digestion.

Aging can lead to diminished senses of taste and smell, reduced salivary secretions, and decreased gastric motility.

Decreased intestinal motility and absorption of nutrients can occur with age, potentially leading to nutritional deficiencies.