- Upon stimulation of the parent cell, the steroid hormone precursors are converted to active hormones and diffuse out of the parent cell by simple diffusion as their intracellular concentration rises. B.2.3. Transport in the blood (Fig. 7-7):- As steroid hormones are derived from cholesterol, they are not soluble in plasma and other body fluids. As a result, steroids are bound to protein carrier proteins. Carrier proteins are either specific or general plasma proteins such as albumin. - Carrier proteins increase the half-life of steroids (one hour to more than a few hours) but block their entry into target cells. B.2.4. Cellular mechanisms of actions of steroid hormones (Fig. 7-7):- Steroids act either slowly by binding to cytoplasmic or nucleic receptors and ultimately activating gene transcription, or quickly by acting on cell surface receptors. B.3. AMINE HORMONES:-The amine hormones are derived from a single amino acid.
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