Sources of EM radiation in organisms?

[KingNothing]

Organisms radiation EM energy. I am aware of the brain and nervous system as a source (because of electrical currents, etc) and that we have a lot of IR radiation.

Is the majority of the energy due to blackbody radiation, a by-product of chemical reactions, or something else?

 

[BruceW]

A 'wave of depolarisation' travels down a neuron cell. This causes (very) small currents at the body surface. Therefore very little energy is radiated due to the electrical activity of the brain and nervous system.
Most of the energy lost by the body is due to conduction from the skin to the air around us, and some is lost by infrared radiation also.

 

[KingNothing]

and some is lost by infrared radiation also.

Which is exactly what I am asking about. Where does that come from?

 

[cjl]

Blackbody, primarily.

 

[BruceW]

Yep. Due to blackbody radiation, the peak in emitted radiation wavelength is at 9.5*(10^-6) meters. So most of the blackbody radiation given off by a human is infrared.
This radiation is given off by all parts of the person (but radiation given off by internal parts of the person may be absorbed by other parts of the person on its way out).
If the person can't be approximated as a blackbody, then I have no idea what will happen.

 

[KingNothing]

What effect does having a non-perfect black body have on the power equation? Does it lower the intensity by some constant factor? (After all, there's only one Halle Berry)

 

[sophiecentaur]

If a body is not exactly black - i.e. it is frequency selective in its emissivity, then i think its surface temperature will always be higher than for a black body, for the same rate of energy loss.