generally , we said that hormone travels to the target organ

via blood stream n a slower transfer speed

 

MY question is ::

 

why is the effect of adrenaline is so fast once we fear ?????

it affects the brain and is produce IN the brain. there are also various glands about the body that produce it also so the physiological effects come about faster than usual. just good distribution and evolution is all.

Um, adrenaline is not produced in the brain, it's produced in the adrenal glands on top of the kidneys.

 

As to why it affects us so fast, my guess would be that it gets dumped right into one of the major veins coming from the kidney (a *lot* of blood goes through the kidneys), from there to the heart, and from there to everywhere.

 

Mokele

i thought there as a small gland in the brain that also produce small amounts?

 

no wonder i din't do biology...

'Slower' is a relative term. It is only a matter of seconds from adrenal gland to brain. In the mean time, you have just had a severe fright. Your brain is in overdrive. You do not notice that adrenaline has not yet kicked in. When it does, it seems to be just a part of the total reaction.

isn't adrenaline besides being a hormone, a neurotransmittor too(at least noradrenaline is, sympathomimetic)?

If we had slow adrenaline, God (Creator, Evolution, whatever) is a real comedian.

isn't adrenaline besides being a hormone, a neurotransmittor too(at least noradrenaline is, sympathomimetic)?

 

Yes like Noradrenaline, Adrenaline/Epinaphrine can act as both although IIRC the fight or flight response is only stimulated through it's action as a hormone.

The_simpsons is right, norepinephrine is both a hormone and a neurotransmitter. Norepinephrine is released from nerve terminals as soon as the signal is sent (sympathetic autonomics), thus the response is virtually instantaneous. Most of the circulatory norepinephrine is spillover from sympathetic nerve endings, rather than from the adrenal medulla. The adrenal medulla is mostly geared towards epinephrine release (though something like 20% is norepi). During sympathetic stimulation, the adrenal medulla releases predominantly epinephrine, but the immediate affect is from the instantaneous release of norepi from nerve terminals. Hope that helps.