The factors responsible for deaths due to heat are:-
a) Degeneration of proteins: Degeneration of proteins which occurs above 45-50°C known as thermal coagulation.
b) Thermal inactivation of enzymes: In some animals such as the Antarctic fish of the genus Trematomus are very sensitive to heat so that above 6°C the proteins denature. Such a low temperature (+6°C) cause denaturation of proteins or inactivation of enzymes in the fish.
c) Inadequate oxygen supply: Thermal death occurs due to inadequate oxygen supply in certain situations. For example, supplying of insects with pure oxygen instead of air does not enable them to survive at a higher temperature.
d) Different temperature effects on interdependent metabolic reactions.
e) Temperature effects on membrane structure: Temperature has profound effects on higher orders of protein structure, protein-lipid interactions, lipid-lipid interactions. Such disturbance in the integrity of membrane function appears to be the primary factor in heat damage to organisms.