![]() ![]() Adipose tissue - Wikipedia. In biology, adipose tissuei, body fat, or simply fat is a loose connective tissue composed mostly of adipocytes. 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. The two types of adipose tissue are white adipose tissue (WAT), which stores energy, and brown adipose tissue (BAT), which generates body heat. The formation of adipose tissue appears to be controlled in part by the adipose gene. Adipose tissue is found in specific locations, which are referred to as adipose depots. Apart from adipocytes, which comprise the highest percentage of cells within adipose tissue, other cell types are present, collectively termed stromal vascular fraction (SVF) of cells. SVF includes preadipocytes, fibroblasts, adipose tissue macrophages, and endothelial cells. Adipose tissue contains many small blood vessels. In the integumentary system, which includes the skin, it accumulates in the deepest level, the subcutaneous layer, providing insulation from heat and cold. ![]() Around organs, it provides protective padding. However, its main function is to be a reserve of lipids, which can be burned to meet the energy needs of the body and to protect it from excess glucose by storing triglycerides produced by the liver from sugars, although some evidence suggests that most lipid synthesis from carbohydrates occurs in the adipose tissue itself. Under normal conditions, it provides feedback for hunger and diet to the brain. For comparison, a mouse with a normal amount of adipose tissue is shown on the right. ![]() ![]() Mice have eight major adipose depots, four of which are within the abdominal cavity. The mesenteric depot forms a glue- like web that supports the intestines and the omental depot (which originates near the stomach and spleen) and - when massive - extends into the ventral abdomen. Both the mesenteric and omental depots incorporate much lymphoid tissue as lymph nodes and milky spots, respectively. The two superficial depots are the paired inguinal depots, which are found anterior to the upper segment of the hind limbs (underneath the skin) and the subscapular depots, paired medial mixtures of brown adipose tissue adjacent to regions of white adipose tissue, which are found under the skin between the dorsal crests of the scapulae. ![]() The layer of brown adipose tissue in this depot is often covered by a . The inguinal depots enclose the inguinal group of lymph nodes. Minor depots include the pericardial, which surrounds the heart, and the paired popliteal depots, between the major muscles behind the knees, each containing one large lymph node. A panniculus complicates surgery of the morbidly obese individual. It may remain as a literal . This condition cannot be effectively corrected through diet and exercise alone, as the panniculus consists of adipocytes and other supporting cell types shrunken to their minimum volume and diameter. Visceral fat is different from subcutaneous fat underneath the skin, and intramuscular fat interspersed in skeletal muscles. Fat in the lower body, as in thighs and buttocks, is subcutaneous and is not consistently spaced tissue, whereas fat in the abdomen is mostly visceral and semi- fluid. Visceral fat is often expressed in terms of its area in cm. VFA, visceral fat area). Excess visceral fat is also linked to type 2 diabetes. Female sex hormone causes fat to be stored in the buttocks, thighs, and hips in women. The most popular of these equations was formed by Durnin and Wormersley, who rigorously tested many types of skinfold, and, as a result, created two formulae to calculate the body density of both men and women. These equations present an inverse correlation between skinfolds and body density. ![]() New formulae are still being created. The cause is likely a combination of genetic, environmental, and behavioral factors that are involved in excess energy intake and decreased physical activity. Substantial weight loss can reduce ectopic fat stores in all organs and this is associated with an improvement of the function of that organ. Human fat tissue contains about 8. ![]() Home; News; Community News; Sports; Menifee Homes; Classifieds. Live LIVE NOW Watch Channel 11 News Live & Replays 24/7; Live LIVE NOW Watch Live Storm Tracker Doppler 11 Radar; Live LIVE NOW Watch Live Video of Breaking News & Events. 1 Tremblay MS, Carson V, Chaput J-P, Dinh T, Duggan M, Faulkner G, Connor Gorber S, Gray CE, Gruber R, Janson K, Janssen I, Katzmarzyk PT, Kho ME, Latimer-Cheung AE. Internships.com is the world Welcome to Crowne Plaza Boston-Natick, the Premier, 100% smoke-free, suburban Boston hotel in Natick. Fully renovated and situated 25 minutes from downtown Boston and.![]() The net direction of this flux is controlled by insulin and leptin. Insulin secretion is stimulated by high blood sugar, which results from consuming carbohydrates. In humans, lipolysis (hydrolysis of triglycerides into free fatty acids) is controlled through the balanced control of lipolytic B- adrenergic receptors and a. A- adrenergic receptor- mediated antilipolysis. Fat cells have an important physiological role in maintaining triglyceride and free fatty acid levels, as well as determining insulin resistance. Abdominal fat has a different metabolic profile. ![]() This explains to a large degree why central obesity is a marker of impaired glucose tolerance and is an independent risk factor for cardiovascular disease (even in the absence of diabetes mellitus and hypertension). This suggests a possible cause- and- effect link between the two, wherein stress promotes the accumulation of visceral fat, which in turn causes hormonal and metabolic changes that contribute to heart disease and other health problems. In addition, adipose- derived stem cells from both human and animals reportedly can be efficiently reprogrammed into induced pluripotent stem cells without the need for feeder cells. Perivascular adipose tissue releases adipokines such as adiponectin that affect the contractile function of the vessels that they surround. This specialized tissue can generate heat by . The process of uncoupling means that when protons transit down the electrochemical gradient across the inner mitochondrial membrane, the energy from this process is released as heat rather than being used to generate ATP. This thermogenic process may be vital in neonates exposed to cold, which then require this thermogenesis to keep warm, as they are unable to shiver, or take other actions to keep themselves warm. Techniques to manipulate the differentiation of . Metabolically active tissue with temperature responses similar to brown adipose was first reported in the neck and trunk of some human adults in 2. Beige adipocytes take on a multilocular appearance (containing several lipid droplets) and increase expression of uncoupling protein 1 (UCP1). Release of catecholamines from sympathetic nerves results in UCP1 activation and usually occurs after extended periods of cold exposure or in response to overfeeding. The drug 2,4- dinitrophenol, which also acts as a chemical uncoupler similarly to UCP1, was used for weight loss in the 1. However, it was quickly discontinued when excessive dosing led to adverse side effects including hyperthermia and death. However, the use of such drugs has proven largely unsuccessful due to several challenges, including varying species receptor specificity and poor oral bioavailability. Browning in response to chronic cold exposure has been well documented and is a reversible process. A study in mice demonstrated that cold- induced browning can be completely reversed in 2. UCP1 seen within a 2. Three regulators of transcription are central to WAT browning and serve as targets for many of the molecules known to influence this process. Among these molecules are irisin and fibroblast growth factor 2. FGF2. 1), which have been well- studied and are believed to be important regulators of browning. Irisin is secreted from muscle in response to exercise and has been shown to increase browning by acting on beige preadipocytes. Studies of WAT browning have greatly benefited from advances in these techniques, as beige fat is rapidly gaining popularity as a therapeutic target for the treatment of obesity and diabetes. DNA microarray is a bioinformatics tool used to quantify expression levels of various genes simultaneously, and has been used extensively in the study of adipose tissue. One such study used microarray analysis in conjunction with Ingenuity IPA software to look at changes in WAT and BAT gene expression when mice were exposed to temperatures of 2. It was discovered that many of the pathways upregulated in WAT after cold exposure are also highly expressed in BAT, such as oxidative phosphorylation, fatty acid metabolism, and pyruvate metabolism. Incorporating RNA- Seq into browning studies is of great value, as it offers better specificity, sensitivity, and a more comprehensive overview of gene expression than other methods. RNA- Seq has been used in both human and mouse studies in an attempt characterize beige adipocytes according to their gene expression profiles and to identify potential therapeutic molecules that may induce the beige phenotype. One such study used RNA- Seq to compare gene expression profiles of WAT from wild- type (WT) mice and those overexpressing Early B- Cell Factor- 2 (EBF2). WAT from the transgenic animals exhibited a brown fat gene program and had decreased WAT specific gene expression compared to the WT mice. This tool has enabled examination of epigenetic regulation of browning and helps elucidate the mechanisms by which protein- DNA interactions stimulate the differentiation of beige adipocytes. Studies observing the chromatin landscapes of beige adipocytes have found that adipogenesis of these cells results from the formation of cell specific chromatin landscapes, which regulate the transcriptional program and, ultimately, control differentiation. Using Ch. IP- seq in conjunction with other tools, recent studies have identified over 3. This hypothesis, originally advanced in the context of glucose metabolism and insulin resistance, has been discredited by physical anthropologists, physiologists, and the original proponent of the idea himself with respect to that context, although according to its developer it remains . When leptin levels drop, the body interprets this as a loss of energy, and hunger increases.
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