Adipose tissue

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Adipose tissue

"Adipose" redirects here. For the Doctor Who monster, see "Partners in Crime
Partners in Crime (Doctor Who)

"Partners in Crime" is the first episode of the Doctor Who of United Kingdom science fiction television series Doctor Who. It was broadcast on BBC One on 5 April 2008....
".

In histology

Histology

Histology is the study of the anatomy of cell and tissue of plants and animals. It is performed by examining a thin slice of tissue under a light microscope or electron microscope....
, adipose tissue or fat is loose connective tissue

Connective tissue

Connective tissue is a form of fibrous biological tissue.It is one of the four types of tissue in traditional classifications .Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 25% of the total protein content....
composed of adipocyte

Adipocyte

Adipocytes are the cell s that primarily compose adipose tissue, specialized in storing energy as fat.There are two types of adipose tissue, white adipose tissue and brown adipose tissue , which are also known as white fat and brown fat, respectively, and comprise two types of fat cells....
s. Adipose tissue is derived from lipoblasts. Its main role is to store energy

Energy

In physics, energy is a scalar physical quantity that describes the amount of Work_ that can be performed by a force. Energy is an attribute of objects and systems that is subject to a conservation law....
in the form of fat

Fat

Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. Chemistry, fats are generally ester of glycerol and fatty acids....
, although it also cushions and insulates

Thermal insulation

The term thermal insulation can refer to materials used to reduce the rate of heat transfer, or the methods and processes used to reduce heat transfer....
the body. Obesity

Obesity

Obesity is a condition in which excess body fat has accumulated to an extent that health may be negatively affected. It is commonly defined as a body mass index of 30 kg/m2 or higher....
or being overweight

Overweight

Overweight is often used interchangeable with pre-obese and is generally defined as having more Adipose tissue than is optimally healthy....
in humans and most animals does not depend on body weight but on the amount of body fat—specifically, adipose tissue.

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Encyclopedia

In histology

Histology

Connective tissue

Adipocyte

Energy

Fat

Thermal insulation

The term thermal insulation can refer to materials used to reduce the rate of heat transfer, or the methods and processes used to reduce heat transfer....
the body. Obesity

Obesity

Overweight

White adipose tissue

White adipose tissue or white fat is one of the two types of adipose tissue found in mammals . In humans, white adipose tissue composes as much as 20% of the body weight in men and 25% of the body weight in women....
(WAT) and brown adipose tissue

Brown adipose tissue

Brown adipose tissue or brown fat is one of the two types of adipose tissue that is present in many newborn or hibernation mammals. Its primary function is to generate body heat....
(BAT). Adipose tissue also serves as an important endocrine organ by producing hormone

Hormone

Hormones are chemicals released by cells that affect cells in other parts of the body. Only a small amount of hormone is required to alter cell metabolism....
s such as leptin

Leptin

Leptin is a 16 Atomic mass unit protein hormone that plays a key role in regulating energy intake and energy expenditure, including appetite and metabolism....
, resistin

Resistin

Resistin is a cysteine-rich protein secreted by adipose tissue of mice and rats. In other mammals, at least primates, pigs and dogs, resistin is secreted by immune and epithelial cells....
and the cytokine

Cytokine

Cytokines are a category of signaling molecules that, like hormones and neurotransmitters, are used extensively in cell communication. They are proteins, peptides or glycoproteins....
TNFa. The formation of adipose tissue appears to be controlled by the adipose gene.

Anatomical features

In humans, adipose tissue is located beneath the skin

Skin

Subcutaneous fat

Subcutaneous fat is found just beneath the skin as opposed to visceral fat which is found in the peritoneal cavity. Subcutaneous fat can be measured using body fat calipers giving a rough estimate of total body adiposity....
), around internal organ

Organ (anatomy)

In biology, an organ is a biological tissue that performs a specific function or group of functions. Usually there is a main tissue and sporadic tissues....
s (visceral fat), and in the bone marrow (yellow bone marrow). Adipose tissue is found in specific locations which are referred to as 'adipose depots.' Adipose tissue contains several cell types, with the highest percentage of cells being adipocyte

Adipocyte

Adipocytes are the cell s that primarily compose adipose tissue, specialized in storing energy as fat.There are two types of adipose tissue, white adipose tissue and brown adipose tissue , which are also known as white fat and brown fat, respectively, and comprise two types of fat cells....
s, which contain fat droplets. Other cell types include fibroblasts, macrophages and endothelial cells. Adipose tissue contains many small blood vessel

Blood vessel

The blood vessels are the part of the circulatory system that transport blood throughout the body. There are three major types of blood vessels: the artery, which carry the blood away from the heart, the capillary, which enable the actual exchange of water and chemicals between the blood and the tissues; and the veins, which carry blood from...
s. In the integumentary system

Integumentary system

The integumentary system is the organ system that protects the body from damage, comprising the skin and its appendages. The integumentary system has a variety of functions; it may serve to waterproof, cushion and protect the deeper tissues, excrete wastes, regulate temperature and is the location of receptors for pain, sensation, pressu...
, 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. Adipose depots in different parts of the body have different biochemical profiles.

Mice

In mice

Mouse

A mouse is a small animal that belongs to one of numerous species of rodents. The best known mouse species is the House Mouse . It is also a popular pet....
, there are eight major adipose depots, four of which are within the abdominal cavity

Abdominal cavity

The abdominal cavity is the body cavity of the human body that holds the bulk of the viscus and which is located below the thoracic cavity, and above the pelvic cavity....
: the paired gonadal depots are attached to the uterus

Uterus

The uterus is a major female hormone-responsive reproductive sex organ of most mammals, including humans. It is within the uterus that the fetus develops during gestation....
and ovaries in females and the epididymis

Epididymis

The epididymis is part of the male reproductive system and is present in all male mammals. It is a narrow, tightly-coiled tube connecting the efferent ducts from the rear of each testicle to its vas deferens....
and testes in males, the paired retroperitoneal depots are found along the dorsal

Dorsal

Dorsal is an adjective which means being at the back.Dorsal may refer to:* Dorsum , a part of an animal* A dorsal consonant, in linguistics...
wall of the abdomen, surrounding the kidney, and when massive extend into the pelvis. The mesenteric depot forms a glue-like web that supports the intestine

Intestine

In anatomy, the intestine is the segment of the Gastrointestinal tract extending from the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine....
s, and the omental depot, which originates near the stomach

Stomach

In most mammals, the stomach is a hollow muscular organ of the gastrointestinal tract involved in the second phase of digestion, following mastication....
and spleen

Spleen

The spleen is an organ found in all vertebrate animals. In humans, the spleen is located in the abdomen of the body, where it functions in the destruction of redundant red blood cells, and holds a reservoir of blood....
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

Skin

The skin is the outer covering of the body, also known as the epidermis. It is the largest organ of the integumentary system made up of multiple layers of epithelial biological tissue, and guards the underlying muscles, bones, ligaments and organ s....
between the dorsal crests of the scapulae. The layer of brown adipose tissue in this depot is often covered by a “frosting” of white adipose tissue, sometimes these two types of fat (brown and white) are hard to distinguish. The inguinal depots enclose the inguinal group of lymph nodes. Minor depots include the pericardial

Pericardial

Pericardial can refer to:* Pericardial sinus* Pericardium...
which surrounds the heart, and the paired popliteal depots, between the major muscle

MUSCLE

MUSCLE is public domain, multiple sequence alignment software for protein and nucleotide sequences.MUSCLE is integrated into UGENE bioinformatics tool as a plugin....
s behind the knees, each containing one large lymph node

Lymph node

A Lymph node is an organ consisting of many types of cells, and is a part of the lymphatic system. Lymph nodes are found all through the body, and act as filters or traps for foreign particles....
. Of all the depots in the mouse, the gonadal depots are the largest and the most easily dissected, comprising about 30% of dissectible fat.

Obesity

In a severely obese person

Person

The term person in common usage means an individual human being. In the fields of law, philosophy, medicine, and others, the term also has specialised context-specific meanings....
, excess adipose tissue hanging downward from the abdomen is referred to as a panniculus

Panniculus

Panniculus is a medical term describing a dense layer of fatty tissue growth, usually in the abdominal cavity. It can be a result of morbid obesity and can be mistaken for a tumor or hernia....
(or pannus

Pannus

Pannus is a medical term for a hanging flap of Tissue . When involving the abdomen, it is called a panniculus and consists of skin, fat, and sometimes contents of the internal abdomen as part of a hernia....
). A panniculus complicates surgery of the morbidly obese. The panniculus may remain as a literal "apron of skin" if a severely obese person quickly loses large amounts of fat (a common result of gastric bypass surgery

Gastric bypass surgery

Gastric bypass procedures are any of a group of similar operations used to treat morbid obesity?the severe accumulation of excess weight as fatty tissue?and the health problems it causes....
). 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. Reconstructive surgery is one method of treatment.

Physiology

Free fatty acid is "liberated" from lipoprotein

Lipoprotein

A lipoprotein is a biochemistry assembly that contains both proteins and lipids. The lipids or their derivatives may be covalently or non-covalently bound to the proteins....
s by lipoprotein lipase

Lipoprotein lipase

Lipoprotein lipase is an enzyme that hydrolyzes lipids in lipoproteins, such as those found in chylomicrons and very low density lipoproteins , into three free fatty acids and one glycerol molecule....
(LPL) and enters the adipocyte, where it is reassembled into triglyceride

Triglyceride

is a glyceride in which the glycerol is esterified with three fatty acids. It is the main constituent of vegetable oil and animal fats....
s by ester

Ester

An ester is an often Aroma compound organic chemistry or partially organic compound formed by the reaction between an acid and an alcohol or aromatic alcohol with the elimination of water....
ifying it onto glycerol

Glycerol

Glycerol is a chemical compound also commonly called glycerin or glycerine. It is a colorless, odorless, Viscosity liquid that is widely used in pharmaceutical formulations....
. Human fat tissue contains about 87% lipids.

In humans, lipolysis is controlled though the balanced control of lipolytic B-adrenergic receptors and a2A-andronergic receptor mediated antilipolysis.

Fat is not laid down when there is a surplus available and stored passively until it is needed; rather it is constantly being stored in and released from each cell.

Fat cells have an important physiological

Physiology

Physiology is the study of the mechanical, physical, and biochemical functions of living organisms. Physiology has traditionally been divided between plant physiology and animal and all living things physiology but the principles of physiology are universal, no matter what particular organism is being studied....
role in maintaining triglyceride and free fatty acid levels, as well as determining insulin resistance

Insulin resistance

Insulin resistance is the condition in which normal amounts of insulin are inadequate to produce a normal Insulin#Physiological_effects from fat, muscle and liver cell ....
. Abdominal

Abdomen

In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity....
fat has a different metabolic

Metabolism

Metabolism is the set of chemical reactions that occur in living organisms in order to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments....
profile—being more prone to induce insulin resistance. This explains to a large degree why central obesity

Central obesity

Central obesity, the "apple-shaped" obesity commonly referred to as belly fat, is the accumulation of visceral fat resulting in an increase in waist size....
is a marker of impaired glucose tolerance and is an independent risk factor for cardiovascular disease

Cardiovascular disease

Cardiovascular disease or cardiovascular diseases refers to the class of diseases that involve the heart or blood vessels . While the term technically refers to any disease that affects the Circulatory system , it is usually used to refer to those related to atherosclerosis ....
(even in the absence of diabetes mellitus

Diabetes mellitus

Diabetes mellitus , often referred to simply as diabetes , is a syndrome of disordered metabolism, usually due to a combination of genetic disorder and environmental causes, resulting in abnormally high blood sugar levels ....
and hypertension

Hypertension

Hypertension, also referred to as high blood pressure, HTN or HPN, is a medical condition in which the blood pressure is chronically elevated....
).

Recent advances in biotechnology have allowed for the harvesting of adult stem cell

Adult stem cell

Adult stem cells are cell differentiation cell , found throughout the body after embryonic development, that multiply by cell division to replenish dying cells and regenerate damaged biological tissue....
s from adipose tissue, allowing stimulation of tissue regrowth using a patient's own cells. The use of a patient's own cells reduces the chance of tissue rejection and avoids the ethical issues associated with the use of human embryonic stem cell

Embryonic stem cell

Embryonic stem cells are stem cells derived from the inner cell mass of an early stage embryo known as a blastocyst. Human embryos reach the blastocyst stage 4?5 days post Human fertilization, at which time they consist of 50?150 cells....
s.

Adipose tissue is the greatest peripheral

Peripheral

A peripheral is a device attached to a host computer behind the chipset whose primary functionality is dependent upon the host, and can therefore be considered as expanding the hosts capabilities, while not forming part of the system's core computer architecture....
source of aromatase

Aromatase

Aromatase is an enzyme of the cytochrome P450 superfamily , whose function is to aromatize androgens , producing estrogens. As such, it is an important factor in sexual development....
in both males and females contributing to the production of estradiol

Estradiol

Estradiol is a sex hormone. Mislabelled the "female" hormone, it is also present in males; it represents the major estrogen in humans. Estradiol has not only a critical impact on reproductive and sexual functioning, but also affects other organs including bone structure....
.

Adipose derived hormones

Adipose derived hormones

Adipose tissue is an important endocrine organ that secretes numerous protein hormones into circulation. These factors are generally referred to as adipocytokines or adipokines, however the strict definition of an adipokine is that it interacts with the immune system....
include:

Adiponectin
Adiponectin

Adiponectin is a protein which in humans is encoded by the ADIPOQ gene....
Resistin
Resistin

Resistin is a cysteine-rich protein secreted by adipose tissue of mice and rats. In other mammals, at least primates, pigs and dogs, resistin is secreted by immune and epithelial cells....
Angiotensin
Angiotensin

Angiotensin causes blood vessels to constrict, and drives blood pressure up. It is part of the renin-angiotensin-aldosterone system, which is a major target for drugs that lower blood pressure....
Plasminogen activator inhibitor-1
Plasminogen activator inhibitor-1

Plasminogen activator inhibitor-1 is the principal inhibitor of tissue plasminogen activator and urokinase , the activators of plasminogen and hence fibrinolysis ....
(PAI-1)
TNFa
IL-6
Interleukin

Interleukins are a group of cytokines that were first seen to be expressed by white blood cells as a means of communication . The name is something of a relic though ; it has since been found that interleukins are produced by a wide variety of body cells....
Leptin
Leptin

Leptin is a 16 Atomic mass unit protein hormone that plays a key role in regulating energy intake and energy expenditure, including appetite and metabolism....
Estradiol
Estradiol

Estradiol is a sex hormone. Mislabelled the "female" hormone, it is also present in males; it represents the major estrogen in humans. Estradiol has not only a critical impact on reproductive and sexual functioning, but also affects other organs including bone structure....
(E2)

Adipose tissues also secrete a type of cytokine

Cytokine

Cytokines are a category of signaling molecules that, like hormones and neurotransmitters, are used extensively in cell communication. They are proteins, peptides or glycoproteins....
s (cell-to-cell signalling proteins) called adipokine

Adipokine

The adipokines or adipocytokines are cytokines secreted by adipose tissue.Members include:* chemerin* interleukin-6 * plasminogen activator inhibitor-1 ...
s (adipocytokines) which play a role in obesity-associated complications.

Brown fat

A specialised form of adipose tissue in human infant

Infant

An infant or baby is the term used to refer to the young offspring of humans....
s, most rodents and small mammals and some hibernating animals, is brown fat or brown adipose tissue

Brown adipose tissue

Brown adipose tissue or brown fat is one of the two types of adipose tissue that is present in many newborn or hibernation mammals. Its primary function is to generate body heat....
. It is located mainly around the neck and large blood vessels of the thorax. This specialised tissue can generate heat by "uncoupling" the respiratory chain of oxidative phosphorylation

Oxidative phosphorylation

Oxidative phosphorylation is a metabolic pathway that uses energy released by the redox of nutrients to produce adenosine triphosphate . Although the many forms of life on earth use a range of different nutrients, almost all carry out oxidative phosphorylation to produce ATP, the molecule that supplies energy to metabolism....
within mitochondria. 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 the cold, who then require this thermogenesis to keep warm as they are unable to shiver

Shivering

Shivering is a bodily function in response to early hypothermia in warm-blooded animals. When the core body temperature drops, the shivering reflex is triggered....
, or take other actions to keep themselves warm.

Attempts to stimulate this process pharmacologically

Pharmacology

Pharmacology is the study of drug action. More specifically it is the study of the interactions that occur between a living organism and exogenous chemicals that alter normal biochemical function....
have so far been unsuccessful, but might in the future be a target of weight loss

Weight loss

Weight loss, in the context of medicine or health or physical fitness, is a reduction of the total body weight, due to a mean loss of fluid, body fat or adipose tissue and/or lean mass, namely bone mineral deposits, muscle, tendon and other connective tissue....
therapy.

Genetics

In 2007, researchers isolated the adipose gene, which apparently serves to keep animals lean during times of plenty. Increased adipose gene activity was associated with slimmer individuals.

Physical properties

Adipose tissue has a density of ~0.9g/ml . Thus, a person with much adipose tissue will float easier than a person with a lot of muscular tissue, since muscular tissue has a density of 1.06 g/ml.

Cultural and social role

Excess adipose tissue on a human can lead to medical problems. For a discussion of the aesthetic and medical significance of body shape, see dieting

Dieting

File:Feet on scale.jpgDieting is the practice of Eating food in a regulated fashion to achieve or maintain a controlled weight. In most cases the goal is weight loss in those who are overweight or obese, but some athletes aspire to gain weight and diets can also be used to maintain a stable body weight....
and obesity

Obesity

Obesity is a condition in which excess body fat has accumulated to an extent that health may be negatively affected. It is commonly defined as a body mass index of 30 kg/m2 or higher....
.

Adipose tissue

Anatomical features

Mice

Obesity

Physiology

Brown fat

Genetics

Physical properties

Cultural and social role

Additional images

See also