Cholesterol in the context of "Cholestanol"

Lipids are a broad group of organic compounds that include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include storing energy, signaling, and acting as structural components of cell membranes. Lipids have applications in the cosmetic and food industries, and in nanotechnology.

Lipids are broadly defined as hydrophobic or amphiphilic small molecules; the amphiphilic nature of some lipids allows them to form structures such as vesicles, multilamellar/unilamellar liposomes, or membranes in an aqueous environment. Biological lipids originate entirely or in part from two distinct types of biochemical subunits or "building-blocks": ketoacyl and isoprene groups. Using this approach, lipids may be divided into eight categories: fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, saccharolipids, and polyketides (derived from condensation of ketoacyl subunits); and sterol lipids and prenol lipids (derived from condensation of isoprene subunits).

Food energy is chemical energy that animals derive from food to sustain their metabolism and muscular activity. This is usually measured in joules or calories.

Most animals derive most of their energy from aerobic respiration, namely combining the carbohydrates, fats, and proteins with oxygen from air or dissolved in water. Other smaller components of the diet, such as organic acids, polyols, and ethanol (drinking alcohol) may contribute to the energy input. Some diet components that provide little or no food energy, such as water, minerals, vitamins, cholesterol, and fiber, may still be necessary for health and survival for other reasons. Some organisms have instead anaerobic respiration, which extracts energy from food by reactions that do not require oxygen.

The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a semipermeable biological membrane that separates and protects the interior of a cell from the outside environment (the extracellular space). The cell membrane is a lipid bilayer, usually consisting of phospholipids and glycolipids; eukaryotes and some archaea typically have sterols (such as cholesterol in animals) interspersed between them as well, maintaining appropriate membrane fluidity at various temperatures. The membrane also contains membrane proteins, including integral proteins that span the membrane and serve as transporters, and peripheral proteins that attach to the surface of the cell membrane, acting as enzymes to facilitate interaction with the cell's environment. Glycolipids embedded in the outer lipid layer serve a similar purpose.

The cell membrane controls the movement of substances in and out of a cell, being selectively permeable to ions and organic molecules. In addition, cell membranes are involved in a variety of cellular processes such as cell adhesion, ion conductivity, and cell signaling and serve as the attachment surface for several extracellular structures, including the cell wall and the carbohydrate cell coat called the glycocalyx, as well as the intracellular network of protein fibers called the cytoskeleton. In the field of synthetic biology, cell membranes can be artificially reassembled.

The liver is a major metabolic organ exclusively found in vertebrates, which performs many essential biological functions such as detoxification of the organism, and the synthesis of various proteins and various other biochemicals necessary for digestion and growth. In humans, it is located in the right upper quadrant of the abdomen, below the diaphragm and mostly shielded by the lower right rib cage. Its other metabolic roles include carbohydrate metabolism, the production of a number of hormones, conversion and storage of nutrients such as glucose and glycogen, and the decomposition of red blood cells. Anatomical and medical terminology often use the prefix hepat- from ἡπατο-, from the Greek word for liver, such as hepatology, and hepatitis.

The liver is also an accessory digestive organ that produces bile, an alkaline fluid containing cholesterol and bile acids, which emulsifies and aids the breakdown of dietary fat. The gallbladder, a small hollow pouch that sits just under the right lobe of liver, stores and concentrates the bile produced by the liver, which is later excreted to the duodenum to help with digestion. The liver's highly specialized tissue, consisting mostly of hepatocytes, regulates a wide variety of high-volume biochemical reactions, including the synthesis and breakdown of small and complex organic molecules, many of which are necessary for normal vital functions. Estimates regarding the organ's total number of functions vary, but is generally cited as being around 500. For this reason, the liver has sometimes been described as the body's chemical factory.

The oat (Avena sativa), sometimes called the common oat, is a species of cereal grass grown for fodder and for its seed, which is known by the same name (usually in the plural). Oats appear to have been domesticated as a secondary crop, as their seeds resembled those of other cereals closely enough for them to be included by early cultivators. Oats tolerate cold winters less well than cereals such as wheat, barley, and rye, but need less summer heat and more rain, making them important in areas such as Northwest Europe that have cool, wet summers. They can tolerate low-nutrient and acid soils. Oats grow thickly and vigorously, allowing them to outcompete many weeds, and compared to other cereals are relatively free from diseases.

Oats are used for human consumption as oatmeal, including as steel cut oats or rolled oats. Global production is dominated by Canada and Russia; global trade is a small part of production, most of the grain being consumed within the producing countries. Oats are a nutrient-rich food associated with lower blood cholesterol and reduced risk of human heart disease when consumed regularly. One of the most common uses of oats is as livestock feed; the crop can also be grown as groundcover and ploughed in as a green manure.

Separating eggs is a process, generally used in cooking, in which the egg yolk is removed from the egg white. This allows one part of the egg to be used without the other part, or each part to be treated in different ways. Recipes for custard call for egg yolks, for example.

The most common reason for separating eggs is so the whites can be whipped. Also, because cholesterol is only found in the yolk, using only egg whites in a recipe will drastically reduce its cholesterol content.

In chemistry, an alcohol (from Arabic al-kuḥl 'the kohl') is a type of organic compound that carries at least one hydroxyl (−OH) functional group bound to a saturated carbon atom. Alcohols range from the simple, like methanol and ethanol, to complex, like sugar alcohols and cholesterol. The presence of an OH group strongly modifies the properties of hydrocarbons, conferring hydrophilic (water-attracted) properties. The OH group provides a site at which many reactions can occur.