Circulation

Circulation - Circulation Organisms exchange materials with...

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Circulation Organisms exchange materials with the environment This ultimately occurs at the cellular level o Nutrients, O2, etc: Enter o Waste, CO2, etc: Exit Endo/exocytosis Circulatory system: Specialized for material transport and exchange o Movement over long distances Diffusion is inefficient o Energy production is constant o Energy need is massive 2 types of circulatory systems Open (insects and smaller animals): No closed pathways, blood and  interstitial fluid sloshes around inside combined (Hemolymph) Closed (worms): Blood confined in blood vessels and heart, not  combined with interstitial fluid o Major advantage: 62,000 miles of vessels in the body: Effective  means of meeting high metabolic demands of large, active  animals, ability to serve every cell and get waste out Metabolic rate is a major factor in the evolution of the circulatory system Higher metabolic rates o More complex CV system, more powerful heart Circulation of mammals Two circuits o Pulmonary – Lungs - Oxygenate
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Circulation o Systemic – Tissues - Deoxygenate Two Pumps o Oxygenated blood to body Left atrium/Ventricle o Deoxygenated blood to lungs Right atrium/Ventricle Composition of blood: In order of level after centrifugation Plasma: Fluid portion of blood o Water, nutrients, pH buffers, some dissolved O2 and CO2,  immune and clotting factors Leukocytes: White blood cells o Cells of the immune system Erythrocytes: Red blood cells o Cells that transport vast majority of O2 throughout the body Hemoglobin found in RBC cytosol has 4 connected  polypeptide subunits An iron atom in each subunit reversibly binds an  O2 molecule Platelets: Cells that secrete clotting factors Heart: Muscular pump that powers circulation Atria: Receive blood from lungs, tissues o
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Circulation - Circulation Organisms exchange materials with...

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