ENVIRONMENTAL EXERCISE PHYSIOLOGY

ENVIRONMENT The sum total of all the conditions and elements which make up the surroundings and influence the development of an individual. This course primarily focuses on the thermal environment, influences of barometric pressure (hypobaria and hyperbaria), quality of air, and microgravity.

ECOLOGY Branch of biology that deals with the relations between living organisms and their environment. An organism is the center of an ecosystem; and is influenced by a multitude of living things and yet capable of resisting to some extent the impact of the environment.

CONFORMING VERSUS REGULATING ORGANISMS The internal conditions of conforming organisms are more closely related to the conditions of the surrounding environment whereas the regulating organisms are capable of maintaining a relatively constant internal environment (homeostasis) despite widely fluctuating environmental conditions

REGULATING ORGANISMS Humans are an excellent example of regulating organisms and because of this ability, the human is referred to as a homeotherm or warm- blooded organism; and consequently can survive in diverse environments (ecosystems).

CONFORMING ORGANISMS Poikilotherm is a cold blooded animal and although they tend to have a wider range of internal variation, they tend to have a narrower environmental survival range than a homeotherm because of a lesser ability to regulate their internal environment.

CONFORMING VERSUS REGULATING ORGANISMS

Early Example of Humans as an Regulating Organism In the 1700’s the Secretary of the Royal Society of London, Mr. Blagden along with his dog, an egg, and a steak entered a room heated to 105 degrees C (221 degrees F) which was above the boiling point for water. Fifteen minutes later the egg was baked hard and the steak was burnt crisp; Mr. Blagden and his dog walked out unharmed (dog was carried in a basket so his feet did not get burned).

THERMAL ENVIRONMENT A biophysical aggregate of air temperature, wind speed, relative humidity, and radiation.

TEMPERATURE The degree of sensible heat or cold; a measure of the escaping tendency of heat from a system (temperature flows or moves from hot areas to cold areas); the property of a system that determines whether or not the system is in thermal equilibrium with other systems.

LAWS OF THERMODYNAMICS Zeroth Law - two systems in thermoequilibrium with a third system are in thermoequilibrium with each other.

LAWS OF THERMODYNAMICS First Law - energy is conserved in any process; the energy gained (or lost) by a system is exactly equal to the energy gained (or lost) by the surroundings. Heat Balance Equation is derived from the First Law of Thermodynamics.

Heat Balance Equation: S = M - (+ W k ) - E + R + C + K S =Heat Storage M = Metabolism W k = Work: where + is positive work representing energy leaving the system and - is negative or eccentric work E = Evaporation: insensible exchange of heat via vaporizing moisture R = Radiation: sensible exchange of heat via electromagnetic waves C = Convection: sensible exchange of heat via a circulating medium K = Conduction: sensible exchange of heat via a static medium

LAWS OF THERMODYNAMICS Second Law - there is always an increase in entropy in any naturally occurring (spontaneous) process. Entropy refers to increasing disorder; or diminished capacity for spontaneous change, as occurs in aging.

LAWS OF THERMODYNAMICS Third Law - absolute zero is unattainable; to approach absolute zero (i.e., the temperature where molecular motion stops) takes increasing amounts of energy. Absolute zero is equal to 0 o Kelvin, o Celsius, or o Fahrenheit.

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