biology 182, 2014 !! lecture 2 - wesleyan...
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Biology 182, 2014 Lecture 2
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Thermoregulating ectotherm (homeotherm)
Heat exchanger
Biology 182, 2014 Lecture 2
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Countercurrent Heat Exchange
Heat exchanger
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van Marken Lichtenbelt, et al. Cold exposure—an approach to increasing energy expenditure in humans. Trends in Energy and Metabolism, in press (2014).
Hypothesis: the hypothalamus is the ‘thermostat’ which regulates metabolism to heat (or not heat) the body. ���Prediction: Heating or cooling the hypothalamus should cause corresponding change in metabolism and body temperature���
Biology 182, 2014 Lecture 2
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Hypothesis: the hypothalamus is the ‘thermostat’ which regulates metabolism to heat (or cool) the body. The data support the hypothesis: Heating or cooling the hypothalamus does cause decrease or increase in metabolism and body temperature
How does the Hypothalamus control so much?
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Figure 41.1 Chemical Signaling Systems
Hormone: an organic chemical substance that is produced at a defined location in an organism and acts at a low concentration to control an aspect of physiology remote from the site of production.
(Howard Bern)
Rhodnius prolixus
Sir VB Wigglesworth (1899 – 1994) and a model organism
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Sir VB Wigglesworth (1899 – 1994) and a model organism
A secreted chemical is necessary for metamorphosis
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See Sadava 41.4
Experiment:
Conclusion:
Hypothesis: Corpus Allatum secretes a chemical which prevents adult molt
Biology 182, 2014 Lecture 2
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See Sadava 41.4
Francesc Villarroya. Irisin, Turning Up the Heat. Cell Metabolism Volume 15, Issue 3 2012 277 - 278
Biology 182, 2014 Lecture 2
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Lipid soluble versus water soluble
Epinephrine
Water Soluble: Peptide (e.g. Growth Hormone) or Amine (e.g. epinephrine). • Packaged into vesicles, released by exocytosis. Freely dissolved in blood. • Do not enter into cells, bind to cell surface receptors.
Lipid soluble: Steroid (e.g. estrogen) or Amine (e.g. thyroxine) • Diffuse through membranes, have carrier proteins in the blood • Bind to cytoplasmic or nuclear receptors
Thyroxine (T3)
Testosterone)
Estrogen