question: Why is the fatty areas of my body so cold during/after a workout?
comment: During a reasonably intense work out, your body is producing quite a lot of heat. To prevent itself from dying it starts sweating in the hope evaporative cooling will allow it to get rid of heat faster. This generally works extremely well. Your fat, however, isn't producing a lot of heat *and* it's a really good thermal insulator - that's why we keep most of it just under the skin. That means that while the skin above muscle gets heated just as quickly as sweating cools it from not only that muscle but also the blood flowing through it, the skin over fatty areas experience the same evaporative cooling but receives less heat.
passages: Heat also effects the viscosity of a fluid inside a capillary. An increase in heat decreases the viscosity of the lumenal fluid. A good example of this action can be observed in the human body during exercise. When a human is exercising, there is an increase in the metabolic rate inside the muscles, creating an increase in heat production. The increase in heat is detected by thermoreceptors, a type of sensory receptor located at various points in body. These receptors send a signal to the brain that tells the body to dilate the blood vessels, including capillaries. This creates a visible change in the number of vessels on the skin. This allows for heat transfer via convection to occur.
   Chafing is caused by clothing rubbing against the skin. Chafing can also be caused by improper or overly loose fitting clothing generating extra friction. Obesity is commonly thought to be the leading cause of thigh chafing, and in some cases losing body fat may help the issue, but the problem is just as noticeable in athletes with well developed quadriceps and people with tight bone structures. Chafing is quite prevalent among long distance athletes such as cyclists or marathon runners due to the extensive time periods during which the skin is in irritating conditions.
   BULLET::::- Arteriolar vasodilation occurs. The smooth muscle walls of the arterioles relax allowing increased blood flow through the artery. This redirects blood into the superficial capillaries in the skin increasing heat loss by convection and conduction.
  
  Section::::In hot and humid conditions.
   Blood circulation transports heat throughout the body, and adjustments to this flow are an important part of thermoregulation. Increasing blood flow to the surface (e.g., during warm weather or strenuous exercise) causes warmer skin, resulting in faster heat loss. In contrast, when the external temperature is low, blood flow to the extremities and surface of the skin is reduced and to prevent heat loss and is circulated to the important organs of the body, preferentially.
  
  Section::::Physiology.:Rate of blood flow.
   Warm anoxia can also occur during reimplantation of the kidney after storage. Lannon showed, by measurements of succinate metabolism, how the kidney was more sensitive to a period of warm hypoxia occurring after storage than to the same period of warm hypoxia occurring immediately prior to storage.
  
  Section::::Nature of kidney preservation injury.:Mechanisms of injury.:Metabolic injury.:Lack of essential nutrients.
  
  Active metabolism of glucose with production of bicarbonate has been demonstrated by Pettersson and Cohen.
   BULLET::::- Eccrine sweat glands under the skin secrete sweat (a fluid containing mostly water with some dissolved ions), which travels up the sweat duct, through the sweat pore and onto the surface of the skin. This causes heat loss via evaporative cooling; however, a lot of essential water is lost.
   Section::::In cold conditions.
  
  BULLET::::- Heat is lost mainly through the hands and feet.
  
  BULLET::::- Sweat production is decreased.
  
  BULLET::::- The minute muscles under the surface of the skin called arrector pili muscles (attached to an individual hair follicle) contract (piloerection), lifting the hair follicle upright. This makes the hairs stand on end, which acts as an insulating layer, trapping heat. This is what also causes goose bumps since humans do not have very much hair and the contracted muscles can easily be seen.
   Cold-sensitive thermoreceptors give rise to the sensations of cooling, cold and freshness.
  
  In the cornea cold receptors are thought to respond with an increase in firing rate to cooling produced by evaporation of lacrimal fluid 'tears' and thereby to elicit a blink reflex.
  
  Section::::Distribution.
   Acetylcholine stimulates muscle to raise metabolic rate.
  
  The low demands of thermogenesis mean that free fatty acids draw, for the most part, on lipolysis as the method of energy production.
  
  A comprehensive list of human and mouse genes regulating cold-induced thermogenesis (CIT) in living animals ("in vivo") or tissue samples ("ex vivo") has been assembled and is available in CITGeneDB.
  
  Section::::Regulation.
   Cold is a primary regulator of BAT processes and induces WAT browning. 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 21 days, with measurable decreases in UCP1 seen within a 24-hour period. A study by Rosenwald et al. revealed that when the animals are re-exposed to a cold environment, the same adipocytes will adopt a beige phenotype, suggesting that beige adipocytes are retained.
   Section::::Clinical significance.:Lymphogenic spread of breast cancer.
  
  Breast cancer typically spreads via lymphatic vessels to the lymph nodes found in the axilla.
  
  Section::::Clinical significance.:Axillary intertrigo.
  
  Excessive perspiration can result in axillary intertrigo. Intertrigo is an inflamed skin condition caused by heat, friction, and moisture. A warm, wet underarm may accommodate the growth of pathogenic bacteria, yeasts, and fungi. The condition is responsible for rash-like symptoms, pustules, or chronic itching or burning in the underarm. Axillary intertrigo is common among those who work in hot environments.
  
  Section::::See also.
  
  BULLET::::- Deodorant
  
  BULLET::::- Perspiration
  
  BULLET::::- Popliteal fossa or "knee pit"
   Section::::Welding process.:Temperature during welding.
  
  Large temperature gradients exist in the electrofusion joint during the fusion cycle. The low thermal conductivity of polymers is the main cause of these large gradients. Recent efforts to model the thermal history at various locations using finite element modeling have been successful. 
  
  Section::::Welding process.:Pressure during welding.
   The scrotum is a pouch-like structure that hangs behind the penis. It holds and protects the testicles. It also contains numerous nerves and blood vessels. During times of lower temperatures, the Cremaster muscle contracts and pulls the scrotum closer to the body, while the Dartos muscle gives it a wrinkled appearance; when the temperature increases, the Cremaster and Dartos muscles relax to bring down the scrotum away from the body and remove the wrinkles respectively.
   Blood flow is directly influenced by the thermodynamics of the body. Changes in temperature affect the viscosity and surface tension of the blood, altering the minimum blood flow rate. At high temperatures the minimum flow rate will decrease and the capillary will expand. This allows heat transfer through the increased surface area of the inner capillary lining and through increased blood flow. At low temperatures the minimum flow rate will increase and the capillary will constrict. This restricts blood flow and decreases the surface area of the capillary, reducing heat transfer.
   Section::::Cardiovascular issues, health, and heart rate.
  
  During aerobic exercise, peripheral veins, particularly those within a muscle, dilate to accommodate the increased blood flow through exercising muscle. The skeletal-muscle pump assists in returning blood to the heart and maintaining cardiac output. A sudden cessation of strenuous exercise may cause blood to pool in peripheral dilated veins which may cause varicose veins. A cool-down period allows a more gradual return to venous tone. The heart will also need to beat faster to adequately oxygenate the body and maintain blood pressure.
   The most widely available types of heated clothing are products for the extremities; the hands and feet. These parts are the most likely to suffer frostbite or frostnip in severe cold. As such, many manufacturers make heated gloves, mittens, socks, and boot liners, which can be purchased at workers' supply stores (serving construction workers) and motor sports stores. Heated torso coverings like vests, jackets, or leggings are available from specialty retailers that cater to motorcyclists and downhill skiers.
   Dogs can stand, walk and run on snow and ice for long periods of time. When a dog's footpad is exposed to the cold, heat loss is prevented by an adaptation of the blood system that recirculates heat back into the body. It brings blood from the skin surface and retains warm blood in the pad surface.
  
  Section::::Physical characteristics.:Dewclaw.
   Vasoconstriction also occurs in superficial blood vessels of warm-blooded animals when their ambient environment is cold; this process diverts the flow of heated blood to the center of the animal, preventing the loss of heat.
  
  Section::::Pathology.
  
  Vasoconstriction can be a contributing factor to erectile dysfunction. An increase in blood flow to the penis causes an erection.
  
  Improper vasoconstriction may also play a role in secondary hypertension.
  
  Section::::See also.
  
  BULLET::::- Addison's disease
  
  BULLET::::- Inotrope
  
  BULLET::::- Hypertension
  
  BULLET::::- Nitric oxide
  
  BULLET::::- Pheochromocytoma
  
  BULLET::::- Shock
  
  BULLET::::- Vasodilation
  
  BULLET::::- Postural orthostatic tachycardia syndrome
  
  BULLET::::- Hemostasis
  
  Section::::External links.
  
  BULLET::::- Definition of Vasoconstriction on HealthScout
   Blood flow to skin and fat are affected by skin and core temperature, and resting muscle perfusion is controlled by the temperature of the muscle itself. During exercise increased flow to the working muscles is often balanced by reduced flow to other tissues, such as kidneys spleen and liver.
   To some degree, all cells of endotherms give off heat, especially when body temperature is below a regulatory threshold. However, brown adipose tissue is highly specialized for this non-shivering thermogenesis. First, each cell has a higher number of mitochondria compared to more typical cells. Second, these mitochondria have a higher-than-normal concentration of thermogenin in the inner membrane.
  
  Section::::Function.:Infants.
   Until recently, brown adipose tissue was thought to be primarily limited to infants in humans, but new evidence has now overturned that belief. Metabolically active tissue with temperature responses similar to brown adipose was first reported in the neck and trunk of some human adults in 2007, and the presence of brown adipose in human adults was later verified histologically in the same anatomical regions.
  
  Section::::Physiology.:Beige fat and WAT browning.
   Retired NFL player Jon Runyan was a star offensive lineman who played most of his career with the nearby Philadelphia Eagles (the Southern Jersey district is a suburb of Philadelphia). In May he took the unusual step of revealing some controversial information about himself: that he was late to pay some taxes and was sued in some business dealings. He says he is "a different type of candidate" by acknowledging his mistakes. With $1.7 million in Adler's campaign account back in April, he has a major cash advantage. "CQ Politics" rates this election as Lean Democrat. Cook rates the district at R+1.
   In addition, glyceroneogenesis in brown adipose tissue is related to thermogenesis in the organism. In mammals, heat is generated by delivering free fatty acids to the mitochondria. When glyceroneogenesis is proceeding regularly, the concentration of free fatty acid is low in intercellular environment because glyceroneogenesis re-esterifies fatty acids to triglycerides. In other words, thermogenesis by free fatty acids is less likely to occur when glyceroneogenesis is proceeding. However, when exposed to cold, a neurotransmitter hormone called norepinephrine will suppress the activity of PEPC-K. When the activity of PEPC-K is suppressed, glyceroneogenesis will be unable to re-esterify the free fatty acids. Eventually, the free fatty acid concentration within the cell will increase leading to excessive free fatty acids in cytosol, which will consequently be delivered to the mitochondria for thermogenesis. Therefore, when a mammal is exposed to cold, heat is generated in the brown adipose tissue by decreasing the activity of glyceroneogenesis.
   Vascular retia mirabilia are also found in the limbs of a range of mammals. These reduce the temperature in the extremities. Some of these probably function to prevent heat loss in cold conditions by reducing the temperature gradient between the limb and the environment. Others reduce the temperature of the testes increasing their productivity. In the neck of the dog, a rete mirabile protects the brain when the body overheats during hunting; the venous blood is cooled down by panting before entering the net.
   When cold, the body attempts to capture heat in the blood by constricting the smooth muscle cells around the microvasculature. The muscle cells are constricted by an increase in calcium. The decreased cross-sectional area for flow increases the vascular resistance and lowers the flow to extremities. This mechanism allows the body to concentrate the heat around the vital organs for survival.
  
  The formula for calculating the systemic vascular resistance is:
  
  formula_3
  
  BULLET::::- SVR as the systemic vascular resistance
  
  BULLET::::- MAP as the mean arterial pressure
  
  BULLET::::- MRAP as the mean right arterial pressure
  
raw_presuppositions: The fatty areas of my body is cold during/after a workout.
raw_corrections: The fatty areas of my body receives less heat during/after a workout as fat is a good thermal insulator. 