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SECTION A ENERGY METABOLISM SECTION B Body Temperature and Its Regulation

SECTION A ENERGY METABOLISM SECTION B Body Temperature and Its Regulation. SECTION A ENERGY METABOLISM. Energy balance Metabolic rate and its evaluation Factors that affect metabolic rate BMR. Measurement of the whole –body metabolic rate. Direct and indirect calorimetry

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SECTION A ENERGY METABOLISM SECTION B Body Temperature and Its Regulation

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  1. SECTION A ENERGY METABOLISM SECTION B Body Temperature and Its Regulation

  2. SECTION A ENERGY METABOLISM • Energy balance • Metabolic rate and its evaluation • Factors that affect metabolic rate • BMR

  3. Measurement of the whole –body metabolic rate • Direct and indirect calorimetry • Thermal equivalent of food • Thermal equivalent of oxygen • Respiratory quotient the ratio of Vco2 produced to Vo2 used

  4. SECTION B Body Temperature and Its Regulation

  5. Body Temperature and Its Regulation • The body temperature, • Balance between heat production and heat loss, • Regulation of body temperature, • fever.

  6. I

  7. II. Balance between heat production and heat loss

  8. 1)Rate of Sweating: In cold weather: the rate of sweat production is essentially zero; In very hot weather: the maximum rate of sweat production is from 1.0L / h to 2~3L / h; During maximal sweating:ten times the normal basal rate of heat production.

  9. 2) Mechanism of sweat secretion: a nervous reflex • The secretory cells:a coiled tubular structure. The sweat is isotonic to blood (an ultrafiltrate of the blood), no protein, and NaCIare the major constituents. • The ductule cell:a long tube, As the fluid moves through the duct, Na+ are removed and water follows. The extent of this concentration depends upon the rate of sweat formation.

  10. • How does the sweat glands handle Na+ and CI- during the secretory process? • When the rate of sweat secretion is very low, the Na+ and CI- concentrations of the sweat are 5 mEq/L, because most of these ions are reabsorbed in the duct from the precursor secretion. • When the rate of secretion becomes progressively greater, the concentration in the sweat rise to maximum levels of about 50~60 mEq/L, because the rate of NaCI reabsorption does not increase proportionally.

  11. • Innervation of the sweat gland •Sympathetic-cholinergic nerve fibers(acetylcholine) , •Muscarinic receptorson the secretory cells are stimulated by the ACh and increase their rate of sweat formation. Effect of aldosterone on Na+ loss in the sweat: Aldosterone increases the rate of active reabsorption of Na+ by the duct. The Na+ reabsorption also carries Cl- along as well. The importance: to minimize loss of NaCl in the sweat when the blood NaCl concentration is already low.

  12. •Two kinds of sweating The thermal sweating: secreting by the small sweat glands in various parts of the body under hot environment. It is a very effective mechanism for heat loss in thermoregulation, and is mainly elicited reflexly The mental sweating: The secretion of sweat by the large sweat glands in palm and foot of the body during nervous and exciting.

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