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Unformatted text preview: Chapter 5 Chemical Messengers I. Mechanisms of Intercellular Communication Direct Communication Through Gap Junctions Fig 5.1a Indirect Communication Through Chemical Messengers- fig 5.1 b GAP JUNCTIONS- Channels formed between 2 cells Direct electrical and metabolic coupling Common in smooth and cardiac muscle Indirect Communication through Chemical Messengers II. Chemical Messengers Functional Classification of Chemical Messengers Chemical Classification of Messengers Synthesis and Release of Chemical Messengers Transport of Messengers Make a chart with these things as the titles and put their characteristics under them Functional Classification of Chemical Messengers Paracrines- releases by the cell, moves , ex: histamine- released with tissue damage and causes dilation of local blood vessels , clotting factors, testosterone- moves from the leydig cells into the seminiferous tubules. Autocrines Neurotransmitters Hormones Neurohormones Cytokines PARACRINES Released by cell, moves to target cell by diffusion Paracrines- act on neighboring cells PROSTAGLANDINS- *paracrine substances * act locally *very potent in small amounts *regulate cellular responses to hormones *can activate or inhibit adenylate cyclase *controls cAMP AUTOCRINES- fig 5.2b NEUROTRANSMITTERS- fig 5.2 b Messengers of nervous system Released from neuron by exocytosis Diffuses to very close target cell across a synapse HORMONES- fig 5.2 d Messenger of endocrine system Released from endocrine gland into blood Transported in blood to target Target cell = cells in body with receptors specific to the hormone NEUROHORMONES Hormones released from the axons of neurons in the hypothalmas ADH & Oxytocin Inhibiting & Releasing hormones into the CYTOKINES Cytokines = peptides or proteins Can be transported in blood Released by most cell types Involved in cell development, differentiation, and immune response Often act on a wide range of targets CHEMICAL CLASSIFICATION OF MESSENGERS Chemical class determines mechanism of transport and mechanism of action on target cell Lipophilic/ Hydrophobic- can cross plasma membrane Lipophobic/ Hydrophilic- can dissolve in plasma or ISF...
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- Spring '11