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HORMON

HORMON. Nove Hidajati Faculty of Veterinary Medicine Airlangga University Surabaya. What is hormon?.

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HORMON

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  1. HORMON Nove Hidajati Faculty of Veterinary Medicine Airlangga University Surabaya

  2. What is hormon? • Many organs in the body secreted biologically active compound called endocrine hormones, which are transported via blood stream to other tissues or organs where they exert a biological effect • As classically defined, is a substance that is synthesized in one organ and transported by the circulatory system to act on another tissue • Hormones can act on adjacent cells (paracrine) • Hormones can act on the cell in which they were synthesized without entering the sistemic circulation (autocrine)

  3. What is the importance of hormones? • Several hormones may control one, process or one hormon may control several process • Provide communication beetween cells, tissues and organs • This comunication is responsible for the regulation of wide range of functions including growth, reproduction, development, homeostasis, and response to external stimuli. Failure in this comunication channels are common and lead to many diseases of the endocrine system

  4. How do hormones act? • In order to act , hormones must interact with other loci on or in the target cell • These sites are termed receptors • A receptor is a locus to which the hormone binds in order to elicit its action

  5. RECEPTOR • A receptor has two function : First, it must be able to distinguish the hormone from all the other chemicals present in the circulation and bind it. The hormone binding sites on receptors have evolved to have unique configurations that are complementary to the hormones they bind. Generally, hormone-receptor interactions are noncovalent in nature and are reversible.

  6. RECEPTOR - Second, the receptor must able to transmit the information gained from the binding to trigger a cellular response. Thus, subtances that bind hormones, even tightly, but do not trigger subsequent responses are not receptors.

  7. Types of Hormones • Hormon can be clasisified in several ways, according: 1-Chemical composition : Cholesterol derivates– this include : glucorticoid, mineralocorticoid, esterogen, progestin Amino acid -tyrosine Polypeptyde-ACTH,TRH Glycoprotein-TSH, FSH, LH 2-Solubility properties-lipophilic dan hidrophilic 3-Location of reseptor 4-Nature of signaling used to mediate hormonal action within the cell

  8. Clasification of hormones by mechanism of action • Group I hormones • Hormon that bind to intracellular receptors • Androgens • calcitriol • esterogens • glucocorticoids • mineralocorticoids • progestins • retinoic acid

  9. Group II Hormones Hormones that bind to cell surface receptors A.The second messenger is cAMP Calcitonin, glucagon, LH, Somatosatin, B.The second mesenger is cGMP Nitric oxide, atrial natriuretic factor C.The second messenger is calcium or phosphatidyl inositols (or both) Gastrin, oxitocyn, cholecistokinin, TRH, Acetilcholin D.The second messenger is a kinase or phosphatase cascade Adponectin, insulin , leptin, GH, Prolactin, IGF-I , IGF-II, EGF

  10. General features of hormon classes

  11. WHERE HORMONES ARE SYNTHESIZED? • Hormones are synthesized in discrete organs designed solely for spesific purpose • Pituitary: TSH, FSH, LH, GH, Prolactin, ACTH • Some organs are disigned to perform two distinct but closely related function • Ovaries produce mature oocyte and reproductive hormones estradiol and progesteron • The testes produce mature spermatozoa and testesterone • Hormones are also produced in specialized cells within other organs • Small intestine : glucagon like peptide • Thyroid : calcitonin • Kydney : angiotensin II • The synthesis of some hormones requires the parenchimal cells of more than one organ • Skin, liver, kidney : calcitriol.

  12. Hormon are synthesized and modified for full activity in a variety of ways • Some hormones are synthesized in final form and secreted immediattely , included in this class are the hormon derived from cholesterol • Others are synthesized in final form and stored in producing cells, example catecholamine • The others hormone synthesized and from precursor molecules in the producing cell, then are processed and secreted upon a physiologic cue, examples insulin • Converted to active forms from precurssor molecules in the periphery, examples: T3, DHT

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