If we connect a load across the battery, the voltage across the terminals drops. This drop in voltage is caused by the internal resistance of the battery. ... Simplified for this circuit, we can say that the voltage drop across both resistors must add up to the voltage of the ideal voltage source.
Didn't you mean ectotherms? But It says right there, ectotherms warm their bodies by absorbing heat from their surroundings, outside their bodies.
