Pathophysiology 4th year Endocrinology Course

 Hormone  Hormonal transport  Hormonal degradation  Membrane/ nuclear receptor  Hypofunction  Hyperfuction 2

 Characteristics of endocrine glands  Definition of hormone  Transport  Effects  Elimination  Regulation  Purely endocrine organs  Endocrine cells in other organs 3

4  The heart  GI tract & derivatives  The placenta  The kidneys  The skin  Adipose tissue

 Hormones are produced and secreted by endocrine cells in trace amounts.  Hormones circulate in the blood to reach all tissues.  Hormones serve as a chemical messenger carrying information  Hormones react only with specific receptor molecules present in certain target cells/tissues.  Hormones have high specificity and affinity receptor binding.  Hormones act in catalytic quantities, frequently activating enzymes.  A single hormone may have multiple effects on a single target tissue, or on several different target tissues.  Hormones start a specific biological response. 5

Hormone actions are initiated at distant cells by binding to specific receptors. In addition to their direct main effects, hormones can have other effects: Synergistic effects Permissive effects Antagonistic effects 6

7  Feedback regulation  Counteracting hormone  Modification of the hormone  Degradation/excretion  Receptor down-regulation  Inactivation of receptor  Intracellular phosphatases

 Synthesis and secretion  Transport  The quality and quantity of receptors  Potential intracellular signaling  Target tissue response  Rate of degradation of hormones Individual levels of hormonal regulation:  Synthesis and secretion  Transport to the target cell  Binding to specific receptors 8

Hyperfunction or hypofunction of the endocrine system Causes:  Hormone hypersecretion or hyposecretion  Disorders of the transport  Disorders of the degradation  Receptor dysfunction 10

 "Down" and "up" regulation  Low sensitivity  Insensitivity (genetic mutations of receptor)  Autoimmune destruction or stimulation  Agonists or antagonists binding  Disorders of complex receptor-G-protein  Production of antibodies against receptors 11

 Insufficient signal strength  High signal strength under inappropriate conditions 1. Inappropriately high hormone levels. 2. Inappropriate receptor activation by agents other than the specific hormone 12

 Decreased sensitivity of receptors  Decreased secretion of hormones  Increase in basal secretion  Disorder of the response to feedback 13

 Iatrogenic hypercortisolism  Performance enhancing drugs  Beer (phytoestrogens)  Soya (fytoandrogens) 14