BIO 203.11 Lecture 3s

BIO 203.11 Lecture 3s - 1 BIO 203: Lecture 3 - Body...

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Unformatted text preview: 1 BIO 203: Lecture 3 - Body Temperature Prof. William Collins Office: 534 Life Sciences Building Office Hours: Tuesdays, 11:30 AM - 12:30 PM Thursdays, 4:00 - 5:00 PM Why Regulate T B ? Reaction Rate 10 o 40 o C T B 20 o 30 o 1 16 Humans 37 o C Birds 39 o C The reaction rate of virtually every process in the body increases exponentially with temperature (rate constant T ) Substrate A Substrate B ATP ADP + P i enzyme 2 Thermal Budget In (Heat Obtained) Out (Heat Lost) Need to examine the principles of heat transfer Conduction Convection Evaporation Radiation Heat gain from external environment Endogenous heat production (metabolism) Heat loss to external environment = Heat Transfer - Conduction Factors that influence heat conduction Temperature Gradient (T 2-T 1 ) is driving force Surface Area (A) of contact influences ease of movement Length between objects ( l ) influences ease of movement Composition of interface influences ease of movement Thermal Conductivity ( ) Heat transfer through physical contact (solids, liquids) T 1 T 2 T 1 = T 2 , no net transfer T 2 > T 1 , net flow from T 2 to T 1 T 1 > T 2 , net flow from T 1 to T 2 3 Physiologists are interested in rates of movement (flow) Differential Equations - (transport equations) flow (of heat) = ease of movement x driving force factors that control rate of heat movement (heat flow) dQ dt = A l ( T 2 T 1 ) Example - heat transfer through physical contact A is surface area of contact l is length between objects is thermal conductivity Heat Transfer - Conduction Thermal Conductivity ( ) metals tissue water air T 1 T 2 ease of movement flow (of heat) driving force dQ dt = A l ( T 2 T 1 ) Where; A is surface area of contact l is length between objects is thermal conductivity (W m-1 K-1 ) 4 Heat Transfer Example Exchange of heat between blood and environment dQ dt = A l ( T B T amb ) skin Blood (T...
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BIO 203.11 Lecture 3s - 1 BIO 203: Lecture 3 - Body...

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