311DCh42 - Ch. 42 pg. 867-895 (869) Two types of systems:...

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Ch. 42 pg. 867-895 (869) Two types of systems: open and closed Three components: circulatory fluid (blood), set of tubes (blood vessels) through which blood moves through the body, muscular pump (heart) Blood pressure – motive force for fluid movement in the circulatory system Open circulatory system – blood bathes the organs directly; no distinction between blood and interstitial fluid, and this general body fluid is termed hemolymph Sinuses – spaces surrounding the organs; one or more hearts pump the hemolymph into an interconnected system; chemical exchange between hemolymph and body cells; when the heart contracts it pumps hemolymph through vessels out into sinuses Ostia - when the heart relaxes it draws hemolymph into the circulatory system through pores Closed circulatory system – blood is confined to vessels and is distinct from the interstitial fluid; one or more hearts pump blood into large vessels that branch into smaller ones coursing through organs Cardiovascular system – closed circulatory system Atria – chambers that receive blood returning to the heart Ventricles – chambers that pump blood out of the heart Arteries, veins, and capillaries – three main kinds of blood vessels Arterioles – small vessels that convey blood to capillaries Capillary beds – networks of vessels that infiltrate each tissue; gases are exchanged by diffusion between blood and the interstitial fluid around tissue cells Venules – capillaries converge into; Arteries carry blood from the heart toward capillaries, and veins return blood to the heart from capillaries; from the liver passes into hepatic vein, which conducts blood to the heart Fish has a ventricle and one atrium; two chambered heart and single circuit of blood flow Gill circulation – blood passes to gills where it picks up oxygen and disposes of carbon dioxide across capillary walls Systemic circulation – oxygen rich blood moved to capillary beds throughout all other parts of the body Amphibians have a three chambered heart and two circuits of blood flow; pulmocutaneous and systemic; some mixing of oxygen rich and oxygen poor blood occurs in the single ventricle Reptiles have a three-chambered heart and two circuits of blood flow; a septum partially divides the single ventricle further reducing mixing of oxygen rich and oxygen poor blood
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Mammals and birds have four-chambered heart that completely segregates oxygen rich and oxygen poor blood Cardiac cycle – one complete sequence of pumping and filling Systole – contraction phase of cycle Diastole – relaxation phase of cycle Cardiac Output – amount left ventricle pumps into systemic circuit ; depends on rate of contraction (heart rate – beats per minute) and stroke volume (amount of blood pumped by the left ventricle in each contraction Atrioventricular valve – between each atrium and ventricle; anchored by strong fibers that prevent them from turning inside out; keep blood from flowing back into the atria; the “lub” is closing of AV valves
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This note was uploaded on 02/01/2011 for the course BIO 311D taught by Professor Reichler during the Spring '08 term at University of Texas at Austin.

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311DCh42 - Ch. 42 pg. 867-895 (869) Two types of systems:...

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