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Although stress response pathways are mediated in different ways depending on the stressor involved, cell type, etc., a general characteristic of many pathways – especially ones where heat is the principal stressor – is that they are initiated by the presence and detection of denatured proteins. Because conditions such as high temperatures ...
Thermophotovoltaic (TPV) energy conversion is a direct conversion process from heat to electricity via photons.A basic thermophotovoltaic system consists of a hot object emitting thermal radiation and a photovoltaic cell similar to a solar cell but tuned to the spectrum being emitted from the hot object.
Most cells in higher organisms maintain an internal environment that is negatively charged relative to the cell's exterior. This difference in charge is called the cell's membrane potential . In the process of depolarization, the negative internal charge of the cell temporarily becomes more positive (less negative).
The heating effect varies with the power and the frequency of the electromagnetic energy, as well as the inverse square of distance to the source. The eyes and testes are particularly susceptible to radio frequency heating due to the paucity of blood flow in these areas that could otherwise dissipate the heat buildup. [7]
The effects of electromagnetic radiation upon living cells, including those in humans, depends upon the radiation's power and frequency. For low-frequency radiation (radio waves to near ultraviolet) the best-understood effects are those due to radiation power alone, acting through heating when radiation is absorbed.
Radiation waves may travel in unusual patterns compared to conduction heat flow. Radiation allows waves to travel from a heated body through a cold non-absorbing or partially absorbing medium and reach a warmer body again. [14] An example is the case of the radiation waves that travel from the Sun to the Earth.
Heat shock proteins are also believed to play a role in the presentation of pieces of proteins (or peptides) on the cell surface to help the immune system recognize diseased cells. [22] The major HSPs involved in the HSR include HSP70, HSP90, and HSP60. [5] Chaperones include the HSP70s and HSP90s while HSP60s are considered to be chaperonins. [17]
An uncoupling protein known as thermogenin is expressed in some cell types and is a channel that can transport protons. When this protein is active in the inner membrane it short circuits the coupling between the electron transport chain and ATP synthesis. The potential energy from the proton gradient is not used to make ATP but generates heat.