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Lacteals
A lacteal is a lymphatic capillary that absorbs dietary fats in the villi of the small intestine. Triglycerides are emulsified by bile and hydrolyzed by the enzyme lipase, resulting in a mixture of fatty acids, di- and monoglycerides. These then pass from the intestinal lumen into the enterocyte, where they are re-esterified to form triglyceride. The triglyceride is then combined with phospholipids, cholesterol ester, and apolipoprotein B48 to form chylomicrons. These chylomicrons then pass into the lacteals, forming a milky substance known as chyle. The lacteals merge to form larger lymphatic vessels that transport the chyle to the thoracic duct where it is emptied into the bloodstream at the subclavian vein. At this point, the fats are in the bloodstream in the form of chylomicrons. Once in the blood, chylomicrons are subject to delipidation by lipoprotein lipase. Eventually, enough lipid has been lost and additional apolipoproteins gained, that the resulting particle (now ref ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intestinal Villus
Intestinal villi (singular: villus) are small, finger-like projections that extend into the lumen of the small intestine. Each villus is approximately 0.5–1.6 mm in length (in humans), and has many microvilli projecting from the enterocytes of its epithelium which collectively form the striated or brush border. Each of these microvilli are about 1 µm in length, around 1000 times shorter than a single villus. The intestinal villi are much smaller than any of the circular folds in the intestine. Villi increase the internal surface area of the intestinal walls making available a greater surface area for absorption. An increased absorptive area is useful because digested nutrients (including monosaccharide and amino acids) pass into the semipermeable villi through diffusion, which is effective only at short distances. In other words, increased surface area (in contact with the fluid in the lumen) decreases the average distance travelled by nutrient molecules, so effectivenes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phospholipids
Phospholipids, are a class of lipids whose molecule has a hydrophilic "head" containing a phosphate group and two hydrophobic "tails" derived from fatty acids, joined by an alcohol residue (usually a glycerol molecule). Marine phospholipids typically have omega-3 fatty acids EPA and DHA integrated as part of the phospholipid molecule. The phosphate group can be modified with simple organic molecules such as choline, ethanolamine or serine. Phospholipids are a key component of all cell membranes. They can form lipid bilayers because of their amphiphilic characteristic. In eukaryotes, cell membranes also contain another class of lipid, sterol, interspersed among the phospholipids. The combination provides fluidity in two dimensions combined with mechanical strength against rupture. Purified phospholipids are produced commercially and have found applications in nanotechnology and materials science. The first phospholipid identified in 1847 as such in biological tissues was lecith ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atherogenesis
Atherosclerosis is a pattern of the disease arteriosclerosis in which the wall of the artery develops abnormalities, called lesions. These lesions may lead to narrowing due to the buildup of atheromatous plaque. At onset there are usually no symptoms, but if they develop, symptoms generally begin around middle age. When severe, it can result in coronary artery disease, stroke, peripheral artery disease, or kidney problems, depending on which arteries are affected. The exact cause is not known and is proposed to be multifactorial. Risk factors include abnormal cholesterol levels, elevated levels of inflammatory markers, high blood pressure, diabetes, smoking, obesity, family history, genetic, and an unhealthy diet. Plaque is made up of fat, cholesterol, calcium, and other substances found in the blood. The narrowing of arteries limits the flow of oxygen-rich blood to parts of the body. Diagnosis is based upon a physical exam, electrocardiogram, and exercise stress test, among ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Low-density Lipoprotein
Low-density lipoprotein (LDL) is one of the five major groups of lipoprotein that transport all fat molecules around the body in extracellular water. These groups, from least dense to most dense, are chylomicrons (aka ULDL by the overall density naming convention), very low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), low-density lipoprotein (LDL) and high-density lipoprotein (HDL). LDL delivers fat molecules to cells. LDL is involved in atherosclerosis, a process in which it is oxidized within the walls of arteries. Overview Lipoproteins transfer lipids (fats) around the body in the extracellular fluid, making fats available to body cells for receptor-mediated endocytosis. Lipoproteins are complex particles composed of multiple proteins, typically 80–100 proteins per particle (organized by a single apolipoprotein B for LDL and the larger particles). A single LDL particle is about 220–275 angstroms in diameter, typically transporting 3,000 to 6,000 fa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adipose
Adipose tissue, body fat, or simply fat is a loose connective tissue composed mostly of adipocytes. In addition to adipocytes, adipose tissue contains the stromal vascular fraction (SVF) of cells including preadipocytes, fibroblasts, vascular endothelial cells and a variety of immune cells such as adipose tissue macrophages. Adipose tissue is derived from preadipocytes. Its main role is to store energy in the form of lipids, although it also cushions and insulates the body. Far from being hormonally inert, adipose tissue has, in recent years, been recognized as a major endocrine organ, as it produces hormones such as leptin, estrogen, resistin, and cytokines (especially TNFα). In obesity, adipose tissue is also implicated in the chronic release of pro-inflammatory markers known as adipokines, which are responsible for the development of metabolic syndrome, a constellation of diseases including, but not limited to, type 2 diabetes, cardiovascular disease and atherosclero ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Very Low-density Lipoprotein
Very-low-density lipoprotein (VLDL), density relative to extracellular water, is a type of lipoprotein made by the liver. VLDL is one of the five major groups of lipoproteins (chylomicrons, VLDL, intermediate-density lipoprotein, low-density lipoprotein, high-density lipoprotein) that enable fats and cholesterol to move within the water-based solution of the bloodstream. VLDL is assembled in the liver from triglycerides, cholesterol, and apolipoproteins. VLDL is converted in the bloodstream to low-density lipoprotein (LDL) and intermediate-density lipoprotein (IDL). VLDL particles have a diameter of 30–80 nm. VLDL transports endogenous products, whereas chylomicrons transport exogenous (dietary) products. In the early 2010s both the lipid composition and protein composition of this lipoprotein were characterised in great detail. Function Very-low-density lipoproteins transport endogenous triglycerides, phospholipids, cholesterol, and cholesteryl esters. It functions a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Liver
The liver is a major Organ (anatomy), organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it is located in the quadrant (anatomy), right upper quadrant of the abdomen, below the thoracic diaphragm, diaphragm. Its other roles in metabolism include the regulation of Glycogen, glycogen storage, decomposition of red blood cells, and the production of hormones. The liver is an accessory digestive organ that produces bile, an alkaline fluid containing cholesterol and bile acids, which helps the fatty acid degradation, breakdown of fat. The gallbladder, a small pouch that sits just under the liver, stores bile produced by the liver which is later moved to the small intestine to complete digestion. The liver's highly specialized biological tissue, tissue, consisting mostly of hepatocytes, regulates a w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lipoprotein Lipase
Lipoprotein lipase (LPL) (EC 3.1.1.34, systematic name triacylglycerol acylhydrolase (lipoprotein-dependent)) is a member of the lipase gene family, which includes pancreatic lipase, hepatic lipase, and endothelial lipase. It is a water-soluble enzyme that hydrolyzes triglycerides in lipoproteins, such as those found in chylomicrons and very low-density lipoproteins (VLDL), into two free fatty acids and one monoacylglycerol molecule: :triacylglycerol + H2O = diacylglycerol + a carboxylate It is also involved in promoting the cellular uptake of chylomicron remnants, cholesterol-rich lipoproteins, and free fatty acids. LPL requires ApoC-II as a cofactor. LPL is attached to the luminal surface of endothelial cells in capillaries by the protein glycosylphosphatidylinositol HDL-binding protein 1 (GPIHBP1) and by heparan sulfated peptidoglycans. It is most widely distributed in adipose, heart, and skeletal muscle tissue, as well as in lactating mammary glands. Synthesis In brief ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subclavian Vein
The subclavian vein is a paired large vein, one on either side of the body, that is responsible for draining blood from the upper extremities, allowing this blood to return to the heart. The left subclavian vein plays a key role in the absorption of lipids, by allowing products that have been carried by lymph in the thoracic duct to enter the bloodstream. The diameter of the subclavian veins is approximately 1–2 cm, depending on the individual. Structure Each subclavian vein is a continuation of the axillary vein and runs from the outer border of the first rib to the medial border of anterior scalene muscle. From here it joins with the internal jugular vein to form the brachiocephalic vein (also known as "innominate vein"). The angle of union is termed the venous angle. The subclavian vein follows the subclavian artery and is separated from the subclavian artery by the insertion of anterior scalene. Thus, the subclavian vein lies anterior to the anterior scalene while the su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thoracic Duct
In human anatomy, the thoracic duct is the larger of the two lymph ducts of the lymphatic system. It is also known as the ''left lymphatic duct'', ''alimentary duct'', ''chyliferous duct'', and ''Van Hoorne's canal''. The other duct is the right lymphatic duct. The thoracic duct carries chyle, a liquid containing both lymph and emulsified fats, rather than pure lymph. It also collects most of the lymph in the body other than from the right thorax, arm, head, and neck (which are drained by the right lymphatic duct). The thoracic duct usually starts from the level of the twelfth thoracic vertebra (T12) and extends to the root of the neck. It drains into the systemic (blood) circulation at the junction of the left subclavian and internal jugular veins, at the commencement of the brachiocephalic vein. When the duct ruptures, the resulting flood of liquid into the pleural cavity is known as chylothorax. Structure In adults, the thoracic duct is typically 38–45 cm in length an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chyle
Chyle (from the Ancient Greek, Greek word χυλός ''chylos'', "juice") is a milky bodily fluid consisting of lymph and emulsified fats, or free fatty acids (FFAs). It is formed in the small intestine during digestion of fatty foods, and taken up by lymph vessels specifically known as lacteals. The lipids in the chyle are colloidally suspended in chylomicrons. Clinical significance A chyle fistula occurs when defect(s) of lymphatic vessel(s) result in leakage of lymphatic fluid, typically accumulating in the thoracic (pleural) or abdominal (peritoneal) cavities, leading to a chylous pleural effusion (chylothorax) or chylous ascites, respectively. Diagnosis of a chyle fistula may be accomplished by analysis of pleural/peritoneal fluid. Identifying the source (localizing the lymphatic defect) is often challenging, but may be accomplished with lymphangiography, which is occasionally associated with a serendipitous therapeutic effect (resolution of the leak), thought to be secondar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chylomicrons
Chylomicrons (from the Greek χυλός, chylos, meaning ''juice'' (of plants or animals), and micron, meaning ''small particle''), also known as ultra low-density lipoproteins (ULDL), are lipoprotein particles that consist of triglycerides (85–92%), phospholipids (6–12%), cholesterol (1–3%), and proteins (1–2%). They transport dietary lipids from the intestines to other locations in the body. ULDLs are one of the five major groups of lipoproteins (sorted by density) that enable fats and cholesterol to move within the water-based solution of the bloodstream. A protein specific to chylomicrons is ApoB48. There is an inverse relationship in the density and size of lipoprotein particles: fats have a lower density than water or smaller protein molecules, and the larger particles have a higher ratio of internal fat molecules with respect to the outer emulsifying protein molecules in the shell. ULDLs, if in the region of 1,000 nm or more, are the only lipoprotein parti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
