Steroid hormone such as aldosterone is secreted by the adrenal cortex
These hormones are lipid soluble molecules that are able to diffuse through plasma membrane of target cells
the hormone combines with a receptor either in the cytoplasm or in the nucleus
ths steroid receptor complex moves theough the nuclear pores and into the nucleus
Steroid receptor complex binds to specific region of DNA stimulatinv the transcription of a gene in DNA
the messenger RNA (mRNA) moves through the nuclear pore into the cytoplasm
The mRNA binds to the ribosomes
Then it is translated into protein or enzyme for certain physiological process
Non steroid homone
Non steroid hormone such as axrenaline act as 1st messenger
the hormone binds to specific receptor proteins in the cell surface membrane
the hormone receptor complex binds with G-protein
Once G-protein is activated , it moves to stimulate the enzyme adenyl cyclase
The activated adenyl cyclase converts ATP into cAMP(cyclic adenosine monophosphate)
cAMP acts as a second messenger and activate protein kinase
The activated protein kinase activates the enzyme phosphorylase which catalyses fhe hydrolysis of glgcogen in glucose
Glucose is oxidised to release energy
At each stage in the process , an amplification process occurs.
Only few of adenyl cyclase are needed to activate many molecule of protein kinase and so on
This is known as cascade effect
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