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! 1) Peptides or proteins Groups of Hormones • Hormones can be classified into three main groups:
! 2) Steroid hormones " Are water soluble and transported by vesicles out of
the cell that made them. " Peptide hormone receptors are localized in the
surface of target cells. " 41 Are lipid-soluble and membrane-permeable " Can diffuse out of the cell that made them. " Can diffuse into the target cells. " In the blood they must be bound to carrier proteins. " The receptors for lipid-soluble hormones are inside
cells, either in the cytoplasm or in the nucleus. " Examples:
insulin " Example: Estrogen Insulin
19 20 Figure 42.11 The Corticosteroid Hormones are Built from Cholesterol 41 Groups of Hormones • Hormones can be classified into three main groups:
! 3) Amine hormones
" Example: epinephrine/adrenaline 22 Figure 15.4 Two Locations for Receptors 41 Nonpolar
hormone Some are water-soluble and some are lipid-soluble. " 21 Are derivatives of the amino acid tyrosine. Polar
hormone Receptors for polypeptide hormones • The receptors for water-soluble proteins are large
glycoproteins on the cell surface with three domains:
! A binding domain projecting outside the plasma
! A transmembrane domain that anchors the receptor in
! A cytoplasmic domain that extends into the cytoplasm
of the cell
• The cytoplasmic domain initiates the target cell’s response
by activating enzymes such as protein kinases or protein
phosphatases. 23 24 41 The insulin receptor 41 Receptors for membrane-permeable Hormones • The receptors for lipid-soluble hormones are inside
cells, either in the cytoplasm or in the nucleus. • The action of lipid-soluble hormones is mediated by
intracellular hormone receptors that usually alter gene
expression. 25 41 The estrogen receptor 26 41 Endocrine glands • Some endocrine cells are single cells within a tissue.
• Digestive hormones, for example, are secreted by
isolated endocrine cells in the wall of the stomach and
small intestine (examples: Gastrin, Secretin,...
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This note was uploaded on 02/13/2014 for the course MCDB 1B taught by Professor Weimbs during the Winter '08 term at UCSB.
- Winter '08