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Unformatted text preview: 1. I ntroducing the Vertebrate Endocrine System • Signaling molecules help integrate cell activities in ways that keep the body → working smoothly- Hormones, neurotransmitters, local signaling molecules and pheromones are signaling molecules in animals- Works on target cells; the “target” is a cell that bears receptors for it; receptors are located in the PR, cytoplasm or nucleus • Hormones→ secretory products of endocrine glands, endocrine cells in tissues, and few neurons- i.e. insulin→ secreted by pancreatic cells into interstitial fluid, diffuses into blood capillaries then bloodstream and transported throughout body; diffuses out of blood into all tissues but only acts on cells that have functioning receptors for it • neurotransmitters→ signaling molecules released from axon endings of neurons which then swiftly activate/inhibit target cells after diffusing across tiny synaptic cleft between them • local signaling molecules→ change chemical conditions in local tissues, as when action of some prostaglandins restricts/enhances blood flow to a tissue • pheromones→ diffuse through water/air to target cells in other individuals of the same species; help integrate social behavior- i.e. soldier termites secrete one pheromone that acts as an alarm signal when ants attack their colony • first hormones discovered by W. Bayliss and E. Starling in early 1900s • gene duplications and modifications may account for diversity in signaling molecules and the receptors for them • endocrine system→ all sources of hormones inside the vertebrate body • most endocrine sources and nervous system interact in intricate ways 2. The Nature of Hormone Action • Hormone response requires 1. Activation of a receptor for that hormone 2. Transduction of receptor’s signal into a molecular form that can exert effects inside the cell 3. Functional response • Responses to hormones vary- Different hormones act on different mechanisms- Not all types of cells are able to respond to a particular hormone...
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This note was uploaded on 05/01/2008 for the course BIOL 101 taught by Professor Hogan during the Spring '08 term at UNC.
- Spring '08