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The Hodgkin-Huxley model: $$I=C_m\frac{dV}{dt} + g_k(V_m - V_k) + g_{Na}(V_m - V_{Na}) + g_l(V_m- V_l)$$ Where $C_m$ is membrane capacitance per unit area and $g_i$ are membrane conductances. Reducing the number of channels does not affect capacitance per se (it does in a way) but what it basically does is to reduce membrane conductance to leak channels ...


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From what I can tell, marine mammals can't dynamically control buoyancy during a dive. They ease the beginning of the dive by starting with a small lung volume to reduce buoyancy. Pinnipeds like seals do this by exhaling half their breath before diving. Deep-diving whales actually breathe in before diving, but their lungs are small relative to body size ...


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I concur with @souvik.bhattacharya but I wish to elaborate on it. The lung collapse indeed stops gas exchange in marine mammals by keeping the air away from the lung tissue that normally exchanges O2, CO2 and N2. Build up of N2 results in the bends after the pressure drops when re-surfacing (McDonald & Ponganis, 2012). However, a study by Hooker et al. ...


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I think I got the answer.... The primary anatomical adaptations for pressure of a deep-diving mammal such as the sperm whale center on air-containing spaces and the prevention of tissue barotrauma. Air cavities, when present, are lined with venous plexuses, which are thought to fill at depth, obliterate the air space, and prevent "the squeeze." The lungs ...


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This scenario is called neutral buoyancy, and it's what marine mammals have, so it doesn't take energy for them to stay still in the water, and it's not particularly hard for them to go up or down when they want to either. Imagine an animal that is as dense as a rock trying to swim up for air, or one that has low density, like a balloon, trying to dive ...



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