Chapter31Sum07

Chapter31Sum07 - How do cells communicate? Direct Paracrine...

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Unformatted text preview: How do cells communicate? Direct Paracrine Endocrine Synaptic - What is a hormone? A chemical signal secreted in the blood that communicates regulatory messages within the body by affecting target cells. Hormones coordinate activities in different parts of the body regulate energy use, metabolism, and growth maintain homeostasis Responses to Hormones Vary Different hormones activate different responses in the same target cell Not all types of cells respond to a particular hormone Chemical signals Local regulators produce changes in cells after being secreted into the interstitial fluid Figure 26.1C Nerve signals Neurotransmitter molecules Nerve cell Nerve cell Act faster than hormones from endocrine system 1. Plasma membrane receptors 2. Intracellular receptors Most hormones derived from amino acids bind to receptor proteins in the target-cell plasma membrane Hormones affect target cells by two main signaling mechanisms (1) A hormone binds to a receptor protein in the plasma membrane Figure 26.2A Hormone (epinephrine) (2) The receptor protein activates a signal- transduction pathway in the cell (3) A series of relay molecules transmits the signal to a protein that carries out the cells response 1 2 3 RECEPTOR PROTEIN TARGET CELL Plasma membrane Relay molecules...
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Chapter31Sum07 - How do cells communicate? Direct Paracrine...

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