Body heating

If it is not dissolved or trapped, an embolism moving from the lower extremities can be life-threatening. People afflicted with phlebitis are particularly susceptible to this problem. A shape-memory trap has been devised that, when deployed in the vena cava, is like a multileaved mesh that traps a traveling embolism, retaining it until medication can dissolve it. Introduced in a folded form by a catheter, the mesh is prevented from deploying by subjecting it to a flow of cold saline water. Once in place, it is released from the catheter and, warmed by body heat, opens into its final shape (11). 

Clothing affects heat and moisture loss. Increasing the thickness or number of layers of clothing increases its insulating capability and reduces body heat loss. Clothing insulation is usually described with the do unit. Originally, t do was defined as the thermal resistance necessary for comfort while sedentary in a uniform still air environment of 21 °C. In conventional SI nomenclature I do has a thermal resistance of 0.155 K m-/W. Some ensembles do values and associated comfort temperatures are shown in Fig. 5.4. 

Airway surfaces, like skin, are continually exposed to the ambient environment. In contrast to skin submucosal vessels, however, w hich shed excess heat by vasodilating when heated and conserve heat by vasoconstricting when chilled, it is unclear how the airway vasculature responds to temperature extremes. Inspiring cold air poses two challenges to conducting airway tissues the risk of tissue injury should inadequate heat reach the airway surface and excessive body heat loss due to increasing the radial temperature gradient. Vasodilation would protect airway tissue but increase heat loss, while vasoconstriction would produce the opposite effect. 

Under certain conditions, such as hyperbaria,airway heat losses can account for a considerable percentage of total body heat production (in some cases > 100%). Normally these threats are ameliorated by rapid moderation of inspired air temperature and humidity by exchanging heat and water vapor between the mucus and airstream in the upper airway. Recovering much of the heat and water vapor contained in expired air minimizes heat and water losses to the ambient environment and aids in whole-body thermoregulation. 

Body heat gain or loss The positive or negative change in the heat content of the human body caused by an imbalance between heat production and heat loss. 

Body heat storage The heat stored in the body due to metabolism. 

Cold stress Physiological stress on the body created by excessive loss of body heat. 

Hyperbolic expansion The expansion of a fluid according to the law pV = Hypothalamus The temperature control center at the base of the brain, which regulates body temperature. Hypothermia The physiological state resulting when the deep core body temperature drops below 35 C. It results in vasoconstriction and shivering in an attempt to conserve body heat. 

Maximum body heat storage (Q, 3, ) The maximum value of the body heat gain achievable by the subject such that the resulting increase in body core temperature does not induce pathological effect, in W h nr-. 

Metabolic heat production The production of body heat due to the intake of oxygen and carbohydrates. 

To release energy, the electrons can be removed from glucose and used to create ATP, a molecule that supplies a cell s short-term energy needs. This latter occurs in a series of reactions known as respiration. (Body heat is a by-product of these reactions.) The most efficient respiration reactions are those that use oxygen to accept the electrons removed from glucose. Thus respiration is the reverse of photosynthe-... 

A human body generates heat at the rate of about 100. W (1 W = l J-s ). (a) At what rate does your body heat generate entropy in your surroundings, taken to be at 20.°C (b) How much entropy do you generate each day (c) Would the entropy generated he greater or less if you were in a room kept at 30.°C Explain your answer. 

Diaphoretic. Because it promotes perspiration by relaxing the pores, elder is a traditional remedy to help the body release toxins through the skin. It increases blood circulation and body heat near the surface of the skin. It has been used to treat blemishes, acne, herpes, psoriasis, measles and chicken pox. Parts used flowers, berries, leaves. 

The skin s mechanism of heat conservation involves its very complex circulatory system [2,3]. To conserve heat, blood is diverted away from the skin s periphery by way of the arteriovenous anastomoses. The ex-ternalmost circulation of the blood is effectively shut down, leading to a characteristic blanching of the skin in fair-skinned individuals. Less heat is irradiated and convectively passed into the atmosphere. Furry mammals have yet another mechanism to conserve body heat. Each tiny arrector pilorum stands its hair up straight, adding appreciable thickness to the insulating air layer entrapped in the fur, reducing heat loss. 

Unfortunately, chickens have no sweat glands, so they cannot perspire. To dissipate any excess body heat during the warm summer months, they must pant just like a dog. Panting increases the amount of carbon dioxide exhaled, itself decreasing the concentration of CO2 in a chicken s blood. The smaller concentration [CO2 ] during the warm summer causes the reaction in Equation (4.60) to shift further toward the left-hand side than in the cooler winter, i.e. the amount of chalk formed decreases. The end result is a thinner eggshell. 

Native to tropical America, sweet potato (I. batatas) is a perennial morning glory vine that has been cultivated for over 5,000 years for its edible tubers in Mexico, Central and lowland South America, and the West Indies. Today, sweet potato is cultivated around the world, especially in developing countries (Plate 4). A decoction made from the leaves of this plant is used in folk remedies as a gargle to treat mouth and throat tumors, and poultices are prepared for inflammatory tumors (64). In Mexico, leaf decoctions are considered to be of cold nature , to reduce excessive body heat, contemporarily defined as such illnesses as diarrhea, dysentery, heart disease, stomach distress, fever, and gastrointestinal infection. In Chinese traditional medicine, the tubers have been used as a medicinal herb to eliminate secretion in perceived abnormal quantities of blood or other body fluids (79). 

Nahuatl, edible root), is an important contribution to world nutrition in addition to have been used by the native population as a cold nature remedy to reduce excessive body heat (A The Latin description in this illustration from the Badianus Manuscript reads Contra cordis calorem, for heat in the heart Libellus de Medicinalibus Indorum Herbis, 1552. Fol. 28v. CONACULTA-INAH-MEX, with permission of the Instituto Nacional de Antropologia e Historia , Mexico). 

Pharmacology The site and mechanism of the analgesic effect is unclear. APAP reduces fever by a direct action on the hypothalamic heat-regulating centers, which increases dissipation of body heat (via vasodilatation and sweating). APAP is almost as potent as aspirin in inhibiting prostaglandin synthetase in the CNS, but its peripheral inhibition of prostaglandin synthesis is minimal. 

Imagine a lizard waking in the morning and stretching out on a warm rock to absorb the heat and raise body temperature to the ideal for action. Later in the day, observe the snake, which like the lizard has warmed itself in the morning, has hunted successfully, and has now produced excess body heat from exercise and the digestion of food. To get rid of the... 

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