lecture04nth - brings regulated variable back into desired...

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1 Nernst equation at equilibrium the tendency for ions to move down their concentration gradient will be exactly balanced by their tendency to move down their electrical gradient ions down concentration gradient ions down electrical gradient Water movement (review) Water moves from lower osmolarity to higher osmolarity (from hyposmotic solution to hyperosmotic solution) tonicity: • hypotonic = cell swells • isotonic = cell does not change volume • hypertonic = cell shrinks The membrane potential will be affected by changes in ion concentration. The membrane potential will affect voltage-gated channels.
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2 Figure 6-19 Sensor detects whether regulated variable is within desired range Controller compares regulated variable level (from sensor) to set point or desired range Effector
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Unformatted text preview: brings regulated variable back into desired range (actions shown in this diagram) Figure 6-20 1. The nervous system has a role in maintaining homeostasis. Figure 6-20 2. Some systems are under tonic control. 3 Figure 6-20 3. Some systems are under antagonistic control. Cannon's Postulates 4. One chemical signal can have different effects in different tissues. [next topic is hormones] Figure 6-22 Local control vs. reflex control 4 Figure 6-23 Figure 6-25 Familiar example of feedback loop Negative vs. positive feedback loop Negative feedback loop - response by effector returns regulated variable BACK to set point or range Positive feedback loop - response by effector sends regulated variable to extreme (runaway process) 5 Figure 22-19 Figure 22-20 Body temperature regulation...
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This note was uploaded on 12/01/2010 for the course BIO SCI Bio Sci E1 taught by Professor Catherineloudin during the Spring '10 term at UC Irvine.

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lecture04nth - brings regulated variable back into desired...

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