Protein HormonesAre Hydrophilic and Carried in the Plasma in Dissolved Form

This chapter focuses mainly on hormones that are trans­ported to target tissues in the vascular system. The means by which hormones are transported in the blood varies accord­ing to the solubility of the hormone. Protein and peptide hormones are hydrophilic and are carried in the plasma in dissolved form. The protein hormones may circulate in mono­meric (single-unit) or polymeric (multiple-unit) form (e.g., insulin). Hormones that have subunits can appear in the cir­culation in subunit form, although this reduces the biological potency of the molecule.