4 Endocrine System 2 What is a Hormone and Disorders

4 Endocrine System 2 What is a Hormone and Disorders -...

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Homeostasis and Endocrine Signaling I. Homeostasis - control systems and feedback regulation II. What is a hormone - principles of endocrinology A. Types of chemical messengers B. Major endocrine organs C. Mechanisms of action D. Amplification of hormonal signals E. Insulin/glucagon and glucose homeostasis F. Anterior pituitary hormones III. Endocrine disorders
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What is a Hormone? A Traditional View: • derived from either cholesterol, amino acids or peptides • secreted by specialized endocrine glands • carried via the blood to distant tissues
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What is a Hormone? - A Functional/Mechanistic View 1) secreted into the circulation 2) produced by virtually all cells 3) act via interaction with specific bound receptors 4) individual hormones commonly exert multiple distinct effects on different organs, or on the same tissue at different times 5) active at very low concentration 6) signals may be highly amplified via cascade mechanisms 7) signaling mechanisms highly conserved evolutionarily 8) negative feedback and antagonistic hormone pairs provide homeostatic balance 9) hormonal cascades and networks provide homeostatic balance
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Fig. 11.5: Types of Chemical Messengers Local signaling Target cell Secreting cell Secretory vesicle Local regulator diffuses through extracellular fluid (a) Paracrine signaling (b) Synaptic signaling Target cell is stimulated Neurotransmitter diffuses across synapse Electrical signal along nerve cell triggers release of neurotransmitter Long-distance signaling Endocrine cell Blood vessel Hormone travels in bloodstream to target cells Target cell (c) Hormonal signaling (endocrine signaling)
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What is a Hormone? - A Functional/Mechanistic View 1) secreted into the circulation 2) produced by virtually all cells 3) act via interaction with specific bound receptors 4) individual hormones commonly exert multiple distinct effects on different organs, or on the same tissue at different times 5) active at very low concentration 6) signals may be highly amplified via cascade mechanisms 7) signaling mechanisms highly conserved evolutionarily 8) negative feedback and antagonistic hormone pairs provide homeostatic balance 9) hormonal cascades and networks provide homeostatic balance
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Fig. 45.10 - Major Endocrine Glands
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This note was uploaded on 10/21/2011 for the course BIO 102 taught by Professor Robinson during the Spring '09 term at UPenn.

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4 Endocrine System 2 What is a Hormone and Disorders -...

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