PEDS200 Lecture : Thermoregulation

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taupewalrus464

22 Dec 2011

School

University of Alberta

Department

Physical Education and Sport

Course

PEDS200

Professor

Dan Syrotuik

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Document Summary

Exercise in the heat - sequence of physiological events: y exercise-induced heat stress + environmental heat stress. y. If exercise continues, core temp. may continue to rise. Cardiovascular drift y gradual increase in hr during prolonged exercise, especially in the heat, even with no change in exercise intensity. Why? y bv is reduced with dehydreation y. If sv drops, hr must increase to maintain q and blood blow for both oxygen delivery and thermoregulation via blood heat transfer. Acclimatization y acclimatization is the physiological adjustements brought about by continuous exposure to various climatic conditions (ex. Occurs as early as 1-4 days and full acclimatization is complete in 10-24 days of exposure. Improved transfer of hear from core, better shunting of the blood d to the periphery and improved vasodilation of surface vessels for. Improved sweat response (begins earlier and increases output) but with electrolyte loss (alterations in aldosterone hormone response in kidneys, helps re-absord na2+ thus plasma evaporative cooling.

Related Questions

Overall, 80% of the energy used by the body must be eliminated as excess
thermal energy and needs to be dissipated. The mechanisms of
elimination are radiation, evaporation of sweat (2 430 𝑘𝐽/𝑘𝑔) evaporation
from the lungs (38 kJ/h), conduction, and convection. A person working
out in a gym has a metabolic rate of 2 500 kJ/h. His body temperature is
37°C, and the outside temperature 24°C. Assume the skin has an area of
2.0 m2 and emissivity of 0.97.
a) At what rate is his excess thermal energy dissipated by
radiation? (4 marks)
b) If he eliminates 0.40 kg of perspiration during that hour, at what
rate is thermal energy dissipated by evaporation of sweat?
c) At what rate is energy eliminated by evaporation from the lungs?
d) At what rate must the remaining excess energy be eliminated
through conduction and convection? (4 marks)

dalitsokamphani11

It is claimed that large trees can evaporate as much as 900kg of water per day. Evaporation takes place from the leaves. To get there the water must be raised from the roots of the tree. Assume the mass evaporated is 1242 kg/day and the average rise of water is 5.58m. What is the average power supplied by the tree, if evaporation occurs only during 12 h of day light?( Hint first how much energy must be supplied)

#7
If all the molecules in a liquid had the same
speed, and some were able to evaporate,
would the remaining liquid be cooled?
1. Yes; there is lower energy left.
2. Yes; evaporation can reduce the speed of
the remaining molecules.
3. No; energy is conserved in the whole sys-
tem.
4. No; the energy of exiting molecules would
be no different than the energy of molecules
left behind.

PEDS200 Lecture : Thermoregulation

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