Protein vs Steroid Hormones

[wrathofgod64]

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Can someone explain why steroid hormones exert long-lasting, delayed effects whereas protein hormones are fast acting? Kaplan says "Steroid hormones typically exert long-lasting, delayed effects because the proteins must be produced before the steroid takes effect. It could therefore be several days before the release of the steroid into the bloodstream results in the production of proteins regulated by estrogen." Protein hormones on the other hand act quickly, and I can't quite understand this. Thanks.

 

[dodjie16]

Steroid hormones are hydrophobic hormones, which means that they will not be able to diffuse through the plasma of the blood. They have to be carried by carrier proteins to the target cells. Once they reach the cell, they will be able to diffuse through the plasma membrane of the cell and bind to receptors on the cytoplasm. The hormones is then taken to the nucleus were it regulates trasncription. This is why their effects are exerted more slowly and can take days.

As for protein hormones (peptide), they are hydropholic hormones. They will be able to diffuse through the plasma of the blood, but not through the plasma membrane of cells. They must attach to receptors on the surface of the cell and activate secondary messengers. The secondary messengers then modify the activity of enzymes in the cytoplasm. It does not regulate transcription, therefore the effects are immediate.