The stomach is a muscular, hollow organ in the gastrointestinal tract of humans and many other animals, including several invertebrates. The stomach has a dilated structure and functions as a vital organ in the digestive system. The stomach is involved in the gastric phase of digestion, following chewing. It performs a chemical breakdown by means of enzymes and hydrochloric acid.
Anemia or anaemia is a blood disorder in which the blood has a reduced ability to carry oxygen due to a lower than normal number of red blood cells, or a reduction in the amount of hemoglobin. The name is derived from Ancient Greek: ἀναιμία anaimia, meaning 'lack of blood', from ἀν- an-, 'not' and αἷμα haima, 'blood'. When anemia comes on slowly, the symptoms are often vague, such as tiredness, weakness, shortness of breath, headaches, and a reduced ability to exercise. When anemia is acute, symptoms may include confusion, feeling like one is going to pass out, loss of consciousness, and increased thirst. Anemia must be significant before a person becomes noticeably pale. Symptoms of anemia depend on how quickly hemoglobin decreases. Additional symptoms may occur depending on the underlying cause. Preoperative anemia can increase the risk of needing a blood transfusion following surgery. Anemia can be temporary or long term and can range from mild to severe.
Digestion is the breakdown of large insoluble food compounds into small water-soluble components so that they can be absorbed into the blood plasma. In certain organisms, these smaller substances are absorbed through the small intestine into the blood stream. Digestion is a form of catabolism that is often divided into two processes based on how food is broken down: mechanical and chemical digestion. The term mechanical digestion refers to the physical breakdown of large pieces of food into smaller pieces which can subsequently be accessed by digestive enzymes. Mechanical digestion takes place in the mouth through mastication and in the small intestine through segmentation contractions. In chemical digestion, enzymes break down food into the small compounds that the body can use.
Pernicious anemia is a disease in which not enough red blood cells are produced due to a deficiency of vitamin B12. Those affected often have a gradual onset. The most common initial symptoms are feeling tired and weak. Other symptoms of anemia may include shortness of breath, lightheadedness, headaches, sore red tongue, cold hands and feet, pale or yellow skin, chest pain, and an irregular heartbeat. The digestive tract may also be disturbed giving symptoms that can include nausea and vomiting, heartburn, upset stomach and loss of appetite. Symptoms of vitamin B12 deficiency may include decreased ability to think, numbness in the hands and feet, memory problems, blurred vision, trouble walking, poor balance, muscle weakness, decreased smell and taste, poor reflexes, clumsiness, depression, and confusion. Without treatment, some of these problems may become permanent.
Parietal cells (also known as oxyntic cells) are epithelial cells in the stomach that secrete hydrochloric acid (HCl) and intrinsic factor. These cells are located in the gastric glands found in the lining of the fundus and body regions of the stomach. They contain an extensive secretory network of canaliculi from which the HCl is secreted by active transport into the stomach. The enzyme hydrogen potassium ATPase (H+/K+ ATPase) is unique to the parietal cells and transports the H+ against a concentration gradient of about 3 million to 1, which is the steepest ion gradient formed in the human body. Parietal cells are primarily regulated via histamine, acetylcholine and gastrin signalling from both central and local modulators.
A gastrectomy is a partial or total surgical removal of the stomach.
Achlorhydria and hypochlorhydria refer to states where the production of hydrochloric acid in gastric secretions of the stomach and other digestive organs is absent or low, respectively. It is associated with various other medical problems.
Digestive enzymes are a group of enzymes that break down polymeric macromolecules into their smaller building blocks, in order to facilitate their absorption into the cells of the body. Digestive enzymes are found in the digestive tracts of animals and in the tracts of carnivorous plants, where they aid in the digestion of food, as well as inside cells, especially in their lysosomes, where they function to maintain cellular survival. Digestive enzymes of diverse specificities are found in the saliva secreted by the salivary glands, in the secretions of cells lining the stomach, in the pancreatic juice secreted by pancreatic exocrine cells, and in the secretions of cells lining the small and large intestines.
The Schilling test was a medical investigation used for patients with vitamin B12 (cobalamin) deficiency. The purpose of the test was to determine how well a patient is able to absorb B12 from their intestinal tract. The test is now considered obsolete and is rarely performed, and is no longer available at many medical centers. It is named for Robert F. Schilling.
Megaloblastic anemia is a type of macrocytic anemia. An anemia is a red blood cell defect that can lead to an undersupply of oxygen. Megaloblastic anemia results from inhibition of DNA synthesis during red blood cell production. When DNA synthesis is impaired, the cell cycle cannot progress from the G2 growth stage to the mitosis (M) stage. This leads to continuing cell growth without division, which presents as macrocytosis. Megaloblastic anemia has a rather slow onset, especially when compared to that of other anemias. The defect in red cell DNA synthesis is most often due to hypovitaminosis, specifically vitamin B12 deficiency or folate deficiency. Loss of micronutrients may also be a cause.
Atrophic gastritis is a process of chronic inflammation of the gastric mucosa of the stomach, leading to a loss of gastric glandular cells and their eventual replacement by intestinal and fibrous tissues. As a result, the stomach's secretion of essential substances such as hydrochloric acid, pepsin, and intrinsic factor is impaired, leading to digestive problems. The most common are vitamin B12 deficiency possibly leading to pernicious anemia; and malabsorption of iron, leading to iron deficiency anaemia. It can be caused by persistent infection with Helicobacter pylori, or can be autoimmune in origin. Those with autoimmune atrophic gastritis (Type A gastritis) are statistically more likely to develop gastric carcinoma, Hashimoto's thyroiditis, and achlorhydria.
The gastric glands are glands in the lining of the stomach that play an essential role in the process of digestion. All of the glands have mucus-secreting foveolar cells. Mucus lines the entire stomach, and protects the stomach lining from the effects of hydrochloric acid released from other cells in the glands.
Hydroxocobalamin, also known as vitamin B12a and hydroxycobalamin, is a vitamin found in food and used as a dietary supplement. As a supplement it is used to treat vitamin B12 deficiency including pernicious anemia. Other uses include treatment for cyanide poisoning, Leber's optic atrophy, and toxic amblyopia. It is given by injection into a muscle or vein.
Subacute combined degeneration of spinal cord, also known as myelosis funiculus, or funicular myelosis, also Lichtheim's disease, and Putnam-Dana syndrome, refers to degeneration of the posterior and lateral columns of the spinal cord as a result of vitamin B12 deficiency (most common), vitamin E deficiency, and copper deficiency. It is usually associated with pernicious anemia.
Vitamin B12 deficiency, also known as cobalamin deficiency, is the medical condition in which the blood and tissue have a lower than normal level of vitamin B12. Symptoms can vary from none to severe. Mild deficiency may have few or absent symptoms. In moderate deficiency, feeling tired, anemia, soreness of the tongue, mouth ulcers, breathlessness, feeling faint, rapid heartbeat, low blood pressure, pallor, hair loss, decreased ability to think and severe joint pain and the beginning of neurological symptoms, including abnormal sensations such as pins and needles, numbness and tinnitus may occur. Severe deficiency may include symptoms of reduced heart function as well as more severe neurological symptoms, including changes in reflexes, poor muscle function, memory problems, blurred vision, irritability, ataxia, decreased smell and taste, decreased level of consciousness, depression, anxiety, guilt and psychosis. If left untreated, some of these changes can become permanent. Temporary infertility reversible with treatment, may occur. In exclusively breastfed infants of vegetarian mothers who don't take B12 supplements as advised, undetected and untreated deficiency can lead to poor growth, poor development, and difficulties with movement.
Vitamin B12, also known as cobalamin, is a water-soluble vitamin involved in metabolism. It is one of eight B vitamins. It is required by animals, which use it as a cofactor in DNA synthesis, and in both fatty acid and amino acid metabolism. It is important in the normal functioning of the nervous system via its role in the synthesis of myelin, and in the circulatory system in the maturation of red blood cells in the bone marrow. Plants do not need cobalamin and carry out the reactions with enzymes that are not dependent on it.
Cyanocobalamin is a form of vitamin B
12 used to treat vitamin B
12 deficiency except in the presence of cyanide toxicity. The deficiency may occur in pernicious anemia, following surgical removal of the stomach, with fish tapeworm, or due to bowel cancer. It is less preferred than hydroxocobalamin for treating vitamin B
12 deficiency. Some study have shown that it has an antihypotensive effect. It is used by mouth, by injection into a muscle, or as a nasal spray.
Haptocorrin also known as transcobalamin-1 (TC-1) or cobalophilin is a transcobalamin protein that in humans is encoded by the TCN1 gene. The essential function of haptocorrin is protection of the acid-sensitive vitamin B12 while it moves through the stomach.
Imerslund–Gräsbeck syndrome is a rare autosomal recessive, familial form of vitamin B12 deficiency caused by malfunction of the "Cubam" receptor located in the terminal ileum. This receptor is composed of two proteins, amnionless (AMN), and cubilin. A defect in either of these protein components can cause this syndrome. This is a rare disease, with a prevalence about 1 in 200,000, and is usually seen in patients of European ancestry.
Cubam, is the term used to refer to a multi-ligand receptor located in the terminal ileum, specializing in absorption of vitamin B12. Cubam is essentially composed of amnionless (AMN), and cubilin. Cubilin is essential as a cell receptor recognizing the "vitamin B12-intrinsic factor" complex, whereas amnionless is more involved in the receptor mediated endocytosis of the complex.
