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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
- Target cell, chemical messengers, Functional Classification of Chemical Messengers, Chemical Messengers II, Chemical Messengers- fig