BIOB11H3 Lecture Notes - Signal Transduction, Autocrine Signalling, Cell Signaling
Document Summary
Fig 15-1: autocrine (a) paracrine (b) and endocrine (c) types of intercellular signalling. Extracellular messengers can travel a short distance and stimulate cells that are in close proximity to the origin of the message, or they can travel throughout the body, potentially stimulating cells that are far away from the source. Autocrine signalling (a): the cell that is producing the messenger expresses receptors on its surface that can respond to that messenger. Thus cells releasing the message will stimulate (or inhibit) themselves. Paracrine signalling (b): messenger molecules travel only short distances through the extracellular space to cells that are in close proximity to the cell that is generating the message. Paracrine messenger molecules are usually limited in their ability to travel around the body because they are inherently unstable or they are degraded by enzymes, or they bind to the extracellular matrix. Messenger molecules reach their target cells via passage through the bloodstream.
