BIO 203 Lecture Notes - Lecture 2: Vasoconstriction, Heat Transfer, Homeostasis
Document Summary
All life is constrained by the laws of physics and chemistry. Physical environment governs what cells can and cannot accomplish. Cells can utilize these laws to their advantage. Clicker question: relative to body size, a large animal has greater surface area for heat exchange with the external environment than a small animal. Clicker: as an animal gets larger, its surface area grows more rapidly than its volume. Answer: false, surface area is squared, whereas volume is cubed. Size principle - relationship between surface area (sa) and volume (v) The sa/v ratio is an index of relative surface area for exchange. A small animal can dissipate the heat more easily than a large animal. Fingers and ears and nose get cold because they have a small surface area to volume. All life can tolerate only a limited range of conditions. Salts, h2o, o2, co2, nutrients, waste elimination, temperature, ph, .