Lecture 16 to 18 Cell signaling

Lecture 16 to 18 Cell signaling - Lecture 16-18: How cells...

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Unformatted text preview: Lecture 16-18: How cells communicated and being regulated: Cell signaling pathway Cell signaling pathway has allowed cells to evolve and respond to the external/ internal environment/message. Anything comes wrong in the signaling pathway results in serious problems such as diseases, cancer and even death. Today, one of the hottest areas in cell biology research is the study of signal transduction. In multicellular organism, It Involve: Signal producing cells: Neuron, endocrine/paracrine/autocrine cells Signals: Chemicals (Ligands) or ions Receptor cell: Ion channel/ Receptors (Intracellular/ Cell surface: Secondary Messengers?) aims to convert (transduce) the chemical signal present on the outside of the cell to different signals inside the cell. Which regulates a lot of cellular functions such as: Receptor and Cell signaling Terms of Cell signaling Saturation : The degree to which receptors are occupied by a messenger. This depends on the affinity of the receptor on the ligand. Affinity : The strength with which a messenger binds to its receptor Competition : The ability of different molecules very similar in structure to combine with the same receptor Antagonist : A molecule that competes for a receptor with a chemical messenger normally present in the body. The antagonist binds to the receptor but does not trigger the cell's response Agonist : A chemical messenger that binds to receptor and triggers the cell's response; eg a drug that mimics a normal messenger's action Down-regulation : A decrease in the total number of target-cell receptors in response to chronic high extracellular concentration of the messenger Up-regulation : An increase in the total number of target-cell receptors in response to a chronic low extracellular concentration of the messenger Endocrine signals are Hormones (produce by endocrine cells in animal) that are broadcasted over the entire organism by secreting the signal into the bloodstream of an animal or the sap of a plant. If a signal is secreted but only diffuses locally, remaining in the neighborhood of the secreting cell, it constitutes a second type of communication termed paracrine signals. Many of these local mediators are responsible for regulating inflammation at sites of infection. If the signal affects the own cell, we call this autocrine (such as Helper T cell activation). Neuronal signals are another method and are exemplified by the neurons in our brains, which send signals over private channels to individual cells. This type of signaling is performed by elongated structures called axons. The axon extends close to the target cell that the neuron will communicate with. A neuron can send electrical signals along its axon, stimulating the influx of calcium ion (as the voltage sensitive calcium channel is opened) with the release of signals called neurotransmitters, which will be received by the target cell....
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This note was uploaded on 07/04/2011 for the course BIOC Point taught by Professor Point during the Spring '11 term at HKU.

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Lecture 16 to 18 Cell signaling - Lecture 16-18: How cells...

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