Cell Communication Notes

Cell Communication Notes - Cell Biology Chapter 16 Notes...

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Cell Biology Chapter 16 Notes Cell Communication I. Cell signaling A. Signal transduction 1. Signaling cell – sends a signal to a target cell via a signal molecule. a.) Signal molecule – carries a message to the target cell. 2. Target cell – detects the signal molecule (receives the message). a.) Receptor proteins 1.) Found on the target cell/receiver 2.) Recognize and respond specifically to the signal molecule B. Signals act over long and short distances. II. 4 categories of signaling A. Neuronal communication (Chapter 12) 1. Neurons delivering messages across long distances. 2. Acts quickly 3. Conversion of electrical impulses to chemical and vice versa. Ex. Poke big toe, stimulus travels along nerves to the brain and converts a stimulus that travels back to the toe indicating pain. B. Endocrine communication 1. Long distance signaling. 2. Very often it occurs through the systemic circulation. 3. Hormones released into the blood stream and bind to receptors to the sites. Ex. Pancreas producing insulin and which regulates glucose uptake in cells all over the body. C. 1. Signaling in the neighborhood or communication to neighboring cells. 2. Act as local mediators to influence neighboring cells—released to the local extracellular space. 3. Depend upon diffusion and regulated by factors that influence diffusion distance/rate. 4. Paracrine vs. Autocrine a.) Autocrine signaling 1.) A certain type of cell will release the signal and the same type of cell will respond to the signal. Ex: epithelial cell communicates with an epithelial cell. b.) Paracrine signaling 1.) A certain type of cell will release the signal and a different type of cell will respond to the signal. Ex: Epithelial communicates with a smooth muscle cell. D. Contact-dependent communication (Juxtacrine) 1. Occurs between two cells that are next to each other. 2. Differece between Juxtacrine and paracrine is that: a.) A cell is never released into the extracellular space b.) The two cells in a sense, hold hands. They must be adjacent and in direct contact with one another. c.) Ex. Occurs when WBC are trying to leave the circulation and enter the site of injury. Signaling molecules expressed on the surface of the epithelial cells are not released into the blood stream but stick to their cell surfaces. The WBCs notice the signal and bind so that the cell can be extravasated into the infection site.
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16-2 III. Cells respond to a limited set of signals A. A sender and a listener are required 1. Sender: a.) The cell sending the signal to the receiver cell. 2. Receptor: a.) Need to be able to hear the signal b.) Ex: in endocrine signaling all of the cells are exposed to the hormones but only the listeners with receptors will hear the signal B. In order to respond to a signal, the cell must have a receptor—either intracellular or on the cell surface. C.
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This note was uploaded on 05/01/2011 for the course BIO 120 taught by Professor Annapowolny during the Fall '10 term at Spelman.

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Cell Communication Notes - Cell Biology Chapter 16 Notes...

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