30. Circulatory systems2

30. Circulatory systems2 - 4/14/11 Circulatory Systems I:...

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4/14/11 1 Circulatory Systems I: Sharing the Wealth 1. We’ll use clickers today – no! 2. Turn in your organismal design homework 3. Let’s pick a convenient time to discuss campus resources for health professions advising, research opportunities, career planning, etc. Circulatory Systems I: Sharing the Wealth • Evolutionary considerations • Common principles of mechanical design • Biological specializations • Plant intercellular transport - water, ions, and sugars • Animal circulation (more in next lecture) General principles Evolution of circulatory systems: organism size >> distance for effective diffusion Different multicellular lineages ----> independent recruitment of O 2 -binding molecules and independent origins of circulatory systems No obvious molecular or structural homologies Good news - common physical principles apply to both non-living and living systems ---> striking design convergences Bad news - each system has its own idiosyncratic terminology – circulation or convection or bulk flow, etc. Evolutionary principles - independent recruitment Analogous proteins carry out similar functions - e.g., oxygen-carrying metalloproteins in circulatory fluids Why do circulatory systems of most insects lack oxygen-carrying pigments? “Blue bloods” - molluscs & crustaceans “Red bloods”- vertebrates Cu -containing hemocyanin aggregated in large proteins ht p:/ en.wikipedia.org/wiki/Hemocyanin ht p:/ fig.cox.miami.edu/~cmal ery/150/chemistry/hemoglobin.jpg Fe -containing hemoglobin packed into red blood cells
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4/14/11 2 Design principles - system components Energy source - for powering the system Pump - any localized structure capable of generating a pressure difference acting over a distance Fluid (gas or liquid) - for carrying matter as dissolved solutes or suspended particles and/or energy as heat Duct/pipe/vessel/pathway - for conveying the fluid down a pressure gradient Regulator - for regulating flow rate Valve - for controlling flow direction Design principles - pumps Driving mechanism - pressure differences for propelling fluids Unlocalized mechanisms - coordinated ciliary beating, peristaltic waves along digestive tract, surrounding muscles squeezing vessels Localized mechanisms – pumps – hearts in animals different organs in plants pump intake outflow Lower positive pressure or Negative pressure Higher positive pressure or Positive pressure pressure difference Δ p = p out - p in Pressure difference is analogous to a concentration difference in diffusion Design principles - system types Closed systems - continuous vessels for fluid transport inside of larger structure - e.g., hot water heating, vertebrate circulation (gases, nutrients, and wastes) “Open” systems - discontinuous vessels within larger structure - e.g., forced air heating, insect circulation (nutrients), brown kelps and vascular plants (sugar transport)
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30. Circulatory systems2 - 4/14/11 Circulatory Systems I:...

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