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 ( Κ ) 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 = Κ∗ A l ∗ ( T 2 − T 1 ) Example - heat transfer through physical contact A is surface area of contact l is length between objects Κ is thermal conductivity Heat Transfer - Conduction Thermal Conductivity ( Κ ) metals tissue water air T 1 T 2 ease of movement flow (of heat) driving force dQ dt = Κ∗ A l ∗ ( T 2 − T 1 ) Where; A is surface area of contact l is length between objects Κ is thermal conductivity (W m-1 K-1 ) 4 Heat Transfer Example Exchange of heat between blood and environment dQ dt = Κ ∗ 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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