Chapters 5 and 6 and 21

Chapters 5 and 6 and 21 - Chapters 5 and 6 Chemical...

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1 Chapters 5 and 6 Chemical Messengers + Endocrine System Receptor Messenger Specificity : interaction required for communication Autocrine and Paracrine Regulators Some control gene expression – Growth factors (e.g. Insulin like Growth Factor) cell growth Some also perform other regulatory functions – Histamine - inflammation – Prostaglandins produced in most organs, diverse functions: • stimulate vasoconstriction some areas, vasodilation in others • prevent damage to stomach lining • needed for blood clotting Many of these regulators are stimulated by hormones Neuroendocrinology Metabolism Behavior Etc. Nervous System Brain + Spinal Cord Endocrine System Release hormones into blood, which bind to specific protein receptors
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2 Classes of Hormones o Function 1. Fast acting 2. Slow or Permissive o Chemical Structure 1. Amino acid derivative - derived by enzymes from tyrosine 2. Proteins/peptide hormone – most common, Pre- + Pro-hormone 3. Steroid hormones - derived from cholesterol in smooth E.R. . Endocrine Gland Blood Stream Cell Membrane Cytoplasm Water Lipid Water Hormone Transport • Hydrophobic hormones need a protein carrier (99% bound) • Must detach from carrier to leave blood and exert effect. • H-Carrier Hormone + Carrier – When a “free” enters/leaves the bloodstream it increases/decreases the “free” hormone concentration A Hormone’s Effect Is Related To. .. I. The concentration of the hormone in the blood, which depends on: a) Rate of secretion b) The quantity of the transport protein c) Rate of metabolism II. The quality and quantity of receptors to which the hormone can bind. The blood contains most hormones, but only those cells that have the specific receptor can respond to a specific hormone.
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3 I. a) Hormone secretion Endocrine glands respond to many types of input, both stimulatory and inhibitory. May respond to metabolites, hormones, ions, and neurotransmitters (nervous system stimulation). The regulation of nearly all hormones involves a negative feedback mechanism I. b) Quantity of transport proteins The quantity of transport proteins is controlled by the Liver ± binding globulin ± albumin (rather non-specific carrier) I. c) Hormone metabolism Many hormones are destroyed as they bind the their receptor. Excess (unused) hormones are removed by: 1. Liver – secreted into bile, excreted in the feces or urine. 2. Kidneys – excreted in the urine. II. Hormone receptors Receptor-hormone affinity. E.g. adrenergic receptors, epinephrine and norepinephrine. Each cell has between 500-100,000 receptors, located in
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Chapters 5 and 6 and 21 - Chapters 5 and 6 Chemical...

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