STRUCTURE;TYPES; AND FUNCTION ADIPOSE TISSUE STRUCTURE;TYPES; AND FUNCTION

WHAT IS ADIPOSE TISSUE? Adipose tissue, or fat, is an anatomical term for loose connective tissue composed of adipocytes. Its main role is to store energy in the form of fat, although it also cushions and insulates the body. Obesity in animals, including humans, is not dependent on the amount of body weight, but on the amount of body fat - specifically adipose tissue. Location: located beneath in the skin, deposits between the muscles but is also found around internal organs (in the intestines and in their membrane folds, around the heart) It is also found in the bone marrow, where it imparts a yellow colour; yellow marrow is most abundant in adults. The fat stored in adipose tissue comes from dietary fats or is produced in the body. white adipose tissue (WAT), which stores energy, and brown adipose tissue (BAT), which generates body heat

Free fatty acids are liberated from lipoproteins by lipoprotein lipase (LPL) and enter the adipocyte, where they are reassembled into triglycerides by esterifying it onto glycerol. Human fat tissue contains about 87% lipids[

TYPES: Types of adipose tissue exist: white adipose tissue (WAT) and brown adipose tissue (BAT). White adipose, the most common type, provides insulation, serves as an energy store for times of starvation or great exertion, and forms pads between organs. When muscles and other tissues need energy, certain hormones bind to adipose cells and trigger the hydrolysis of triacylglycerol, resulting in the release of energy-rich fatty acids and glycerol—a process known as lipolysis. The enzyme responsible for hydrolysis is lipase, which occurs in the blood, White adipose tissue also is a source of a number of different hormones, which serve various roles in metabolism and endocrine function. The adipose-produced hormones adiponectin, leptin, and resistin are involved in energy metabolism, for example, whereas plasminogen activator inhibitor-1 prevents the dissolution of blood clots.

Brown adipose, found mainly in newborn animals, generates heat and actually consumes energy. In humans, the percentage of brown adipose found in the body decreases with age. Brown adipose, by consuming energy, releases heat, which is vital for awakening and emergence from dormancy. Brown adipose tissue typically is tan to red in colour. Its colour and heat-generating properties are imparted by the abundance of organelles known as mitochondria found in brown fat cells. (Mitochondria are the energy-producing components of cells.)

WAT Adipocytes BAT Adipocytes a narrow rim of cytoplasm with its nucleus pressed near the margin of the cell surrounding Cytoplasm throughout the cell with a central nucleus and a single large membrane-enclosed lipid droplet many small lipid droplets few mitochondria many mitochondria (providing the brown color) modest blood supply rich blood supply serves as a depot of stored energy function is to generate heat

Browning of WAT, also referred to as “beiging”, occurs when adipocytes within WAT depots develop features of BAT. Beige adipocytes take on a multilocular appearance (containing several lipid droplets) and increase expression of uncoupling protein 1 (UCP1).[43] In doing so, these normally energy-storing adipocytes become energy- releasing adipocytes.

Adipose derived hormones include: Adiponectin Resistin Plasminogen activator inhibitor-1 (PAI-1) TNFα IL-6 Leptin Estradiol (E2)

Function: Around organs, it provides protective padding. It also functions as a reserve of nutrients. 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—being more prone to induce insulin resistance