lecture2-11

lecture2-11 - lecture 2 -cellular function/regulation a...

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•a coordinated physiological response like this involving multiple organs requires communication between cells, tissues and organs. •how is this accomplished? (how are signals sent and received in the body?) lecture 2 -cellular function/regulation
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The integrator/effector has to have a way of communicating with the billions of cells in body. -how? There are several different ways this is done pancreas brain nerve signals hormones integrating centers are located in various places: •the brain is an obvious integrating center •but, for example, the pancreas could control blood glucose with no input from nervous system. endocrine nervous neuro-endocrine
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general property of hormones (endocrine regulation): •produced in distinct glands •travel in circulatory system •response slow (minutes to days) •can cause long-term changes (e.g., sex steroids) •a few hormone-producing cells and control many cells (!) •all cells are exposed, but only those with specific receptors respond •hormones work at very low concentrations: example: plasma glucagon ! 50 x 10 -12 g/ml •hormones must be removed from circulation – either inactivated by enzymes or excreted in urine (example: insulin half-life ! 5-8 minutes) H H H H H hormone produced by endocrine glands (usually cells specialize in producing single hormone) all cells are exposed but only those with receptors respond
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nervous regulation: •information travels by nerve cells to target organs (muscles, glands, etc.) •very fast response (fractions of seconds) •very small target (limited number of cells innervated ) •short lived signals question: what type of responses would you want to regulate with hormones and what type with the nervous system, and why? Nervous and Endocrine systems overlap:
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lecture2-11 - lecture 2 -cellular function/regulation a...

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