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Chapter 4

Chapter 4. Extracellular signals: Hormones, cytokines and growth factors. Objectives. Understand the general role of Hormones, Cytokines, Growth Factors and Neurotransmitters Learn the abbreviations for the general molecules in each class

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Chapter 4

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  1. Chapter 4 Extracellular signals: Hormones, cytokines and growth factors

  2. Objectives • Understand the general role of Hormones, Cytokines, Growth Factors and Neurotransmitters • Learn the abbreviations for the general molecules in each class • Know one example of a function for each group of signals

  3. Hormones • Small water soluble molecules • Cannot cross plasma membrane • Must target cellular receptor • Examples • Histamine • Epinephrine

  4. Hormones • Peptide Hormones • Water soluble • Stored in vacuoles • Pro-peptides • Examples • Insulin • Glucagon • LH (luteinizing hormone) • FSH (follicle stimulating hormone)

  5. Hormones • Lipophilic molecules (extracellular) • Still need a receptor • Prostaglandins • Synthesized from arachidonic acid • Usually have to do with inflammation

  6. Hormones • Lipophilic molecules (intracellular) • Receptors are on the inside of the cell • Steroid hormones • Examples • Testosterone • Progesterone • Thyroxine

  7. Hormones • Plant hormones (for Joe!!) • All extracellular signals • Auxin • Young leaves and seeds • Very diverse effects • Cytokinins • Developing seeds • Gibberellins • Young shoots and seeds • Flowering and germination • Abscisic acid • Roots and mature leaves • Stromal closure • Ethylene • Gas • Fruit ripening

  8. Cytokines • Very large family of peptides • Range in size from 10-70 kDa

  9. Cytokines • Interleukins • 37 family members • IL-x • Many different sizes • Many different receptors • Many different functions • Immune response and maturation • Can activate themselves or nearby cells

  10. Cytokines • Interferons • Type I • IFN-α, INF-β, IFN-Ω • Type II • INF-γ • Anti-tumor properties? • Tumor necrosis factors • TNF-α and TNF-β • Works closely with IFN and causes necrosis of tumors (hence the name!!)

  11. Growth Factors • Platelet-derived growth factors (PDGF) • Induces cell migration & proliferation • Fibrosis and arteriosclerosis • Epidermal growth factor (EGF) • Various functions • Fibroblast growth factor (FGF) • Cell proliferation, migration and motility • Proto-oncogenes?

  12. Neurotransmitters • Stored in vesicles, released upon Ca2+ stimulation • Small Molecules • Acetylcholine, GABA, dopamine, γ-aminobutyric acid • Glycine, glutamate, ATP and adenosine • Neuropeptides • Substance P, Endorphin, vasopressin

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