Ch18NotesSum11

Ch18NotesSum11 - Fig. 18-1, p. 607 Ch. 18 The Endocrine...

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1 Fig. 18-1, p. 607 Ch. 18 – The Endocrine System • = all cells, tissues, and organs that produce hormones (= chemical messengers) that have effects on target cells elsewhere in the body • Is needed to control coordinated, widespread activities and gradual, sustained, long-term processes – E.g. metabolism, growth, development, reproduction, etc. Table 18-1, p. 605 Intercellular communication (local hormones) (the nervous system) = long distance control (generally)
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2 Nervous vs. endocrine control Typically negative feedback Typically negative feedback Control mechanism Generally longer Generally briefer Duration of effect Seconds, minutes, hours, or days Usually milliseconds Time to effect Change in metabolic activities of target cells Muscle contraction, glandular secretion, neurotransmitter release Results of stimulus All body cells that have receptors for hormone (= target cells) Muscle cells, glands, adipose, other neurons Cells affected Hormone released into ECF, transported in blood Neurotransmitter released at synapse Control messenger Endocrine Nervous Characteristic Fig. 18-1, part 1, p. 607 An overview of the endocrine system, part 1
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3 Fig. 18-1, part 2, p. 607 An overview of the endocrine system, part 2 Classes of hormones • There are 3 main groups based on chemical structure : –1. Amino acid derivatives (biogenic amines) –2. Peptide hormones –3. Lipid derivatives Fig. 18-2, p. 608
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4 Fig. 18-2, part 1, p. 608 Amino acid derivatives Peptide hormones Fig. 18-2, part 2, p. 608
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5 Fig. 18-2, part 3, p. 608 Lipid derivatives Mostly paracrine (local); discussed in other chapters Hormone transport and breakdown • Transport of hormones : – A. Water-soluble hormones –are not bound to carrier molecules; they freely circulate in the bloodstream • E.g. catecholamines, peptides, and proteins • They bind to receptors located on the outer surface of target cells • They remain active (able to bind to a receptor on a target cell) ~ 2 minutes to 1 hour – B. Lipid-soluble hormones – are bound to water-soluble carrier molecules when in the bloodstream • E.g. steroids and thyroid hormones • They bind to receptors located within target cells • They form a long-lasting (several weeks’ supply) hormone reserve : – An equilibrium exists between “bound” (to carriers) hormones and “free” (active; NOT bound to carriers) hormones – The free hormones are usually a very small % of the total amount of hormones in circulation (~ 1%) – More bound hormones are released from their carriers as the free hormones are used up • Hormones are removed from circulation when they : – 1. Bind to receptors on or within target cells – 2. Are broken down by enzymes in the liver or kidneys – 3. Are broken down by enzymes in the blood plasma or ECF
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6 Hormone receptors and target cells Fig. 18-3, p. 610 Fig. 18-4a, p. 612 Receptor = usually a protein or glycoprotein, located: – On the outer surface of the cell membrane (cell
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This note was uploaded on 12/29/2011 for the course BIOLOGY 24011 taught by Professor Pan during the Fall '11 term at HCCS.

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Ch18NotesSum11 - Fig. 18-1, p. 607 Ch. 18 The Endocrine...

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