July 3 2013 Lecture 5 Ch 50 Sections 50 1 50 5 Pre read Ch 49 1 Compare and contrast the structures and advantages of open and closed circulatory systems 2 Explain the differences in vertebrate circulatory systems 3 Describe how blood flows through the heart and how the heart contracts to move the blood Circulatory systems transport materials around the body Unicellular Direct exchange with environment as opposed to circulatory system Trickles down from heart to all of the cells and is picked up at the bottom Small aquatic organisms Exchange through thin tissues Cardiovascular system True circulatory system Gastrovascular system Cavities that bring the external environment into the animal Jellyfish flatworms Inactive slow Open circulatory system Found in arthropods mollusks and other invertebrates Some mollusks do have closed circulatory systems Still have a muscular pump heart Pump acts similar to a fountain Hemolymph Ostia Extracellular fluid and blood have no differentiation Fluid within circulatory system Return fluid at the bottom of organism back to the heart Closed circulatory systems Everything contained within vessels Vascular system Where blood is found Closed circulatory systems have advantages Rapid flow Fluid moves quickly through all of the vessels Varying vessel diameter Change the size of the vessels which helps to control blood flow Can divert blood flow Retain specialized cells in vessels Hearts Fluid is pumped by one with two or more chambers All vertebrates have closed circulatory systems Some invertebrates do Annelids leeches do Insects Do not have circulatory system connected to respiratory system Allows flight Closed circulatory systems move blood to and from the heart From the heart to the lungs then back to the heart From the heart to the body then back to the heart Gas exchange organs Gills or lungs in pulmonary circuit Pulmonary circuit Systemic circuit Arteries Away Arterioles Capillary beds Venules Veins Towards Heart arteries arterioles capillaries veins venules heart Vertebrate groups have different characteristics to their circulatory systems Most fish Two chambered heart Atria and ventricle Aorta Pressure changes Pressure drops dramatically from heart into gills The lungfish circulatory system represents a transition to air breathing Modified resistance so that there is lungflow to the lungs Lungfish lung Part of gills modified Two atria Separate circuits One atria brings in blood from the body and one brings in blood from the lungs Can shunt blood to travel to body instead of lung Blood primarily stays separated in ventricle Oxygen rich blood bypasses the gills and goes straight into the body Amphibians have a three chambered heart Three chambered heart Right atrium left atrium single ventricle Single ventricle pumps blood to the lungs and to the body Left atria receives oxygenated blood from the lungs Right atria receives deoxygenated blood from the tissues Two atria Separate circuits Limited mixing Flow of deoxygenated blood directed towards lungs by ventricle Flow of oxygenated blood directed towards tissues by ventricle Amphibians also use skin for gas exchange Skin systemic capillaries Ectothermic reptiles turtles snakes lizards have a partially divided ventricle Partially divided ventricle Allows organisms to have short bursts of energy Do not need to breathe continuously Have a bypass that allows organisms to bypass pulmonary circuit when not breathing Septum Intermittent breathing Two aortas Blood from either ventricle Right deoxygenated Left oxygenated Slide has picture of crocodile heart Crocodiles have completely divided ventricles Two aortas Shunt Blood from either ventricle Maintained because intermittent breathing is still occurring Birds and mammals have completely divided ventricles No blood mixing No shut no intermittent breathing You maximize gas exchange Maximize gas exchange Blood is 100 saturated with oxygen Separate systems act at different pressures Divide between circuits Less pressure going to pulmonary circuit More pressure going to systemic circuit Left is more muscular Four chambered heart The mammalian heart delivers blood to the lungs from the right to the body from the left Red oxygenated Blue deoxygenated To the body From the lungs To the lungs From the body Valves Backflow Superior inferior vena cava Blood flows from the right side of the heart to the lungs to the body back to the right side Empty into the right atrium Right atrium through first valve tricuspid into the right ventricle Moves from RV into pulmonary semilunar valve and into pulmonary artery Pulmonary artery vein Out of pulmonary artery into lungs Leave lungs Back into the pulmonary vein Into the left atrium Through valve bicuspid Into left ventricle Moves through aortic semilunar into aorta and out through the body Be able to trace the heart from any point Semilunar Between ventricles Pulmonary Aortic The cardiac cycle refers to the rhythmic contraction of the heart Starts with contraction of atria right and left contract at same time This forces blood into the ventricles First sound lub is when AV valves close While valves are closing the semilunar valves are opening Then contract ventricles and move blood Ventricles relax and semilunar valves close dub Blood pressure is measured using a sphygmomanometer Systolic value higher Minimum pressure needed to compress artery Diastolic value 0 blood flow Minimum pressure that causes flow through artery The heartbeat is generated in cardiac muscle Gap junctions Pacemaker cells initiate muscle contraction without nervous cells Sinoartial node Atrioventricular node Message passed through HIS Then through purkinje fibers Then ventricles contract http www youtube com watch v waOSUpEHPQs Blood is composed of plasma and cellular components Nutrient waste products Respiratory gases Hormones Heat Erythropoietin Hematocrit Can use blood to dissipate heat The amount of cellular components found in blood Centrifuged Cellular material at bottom KNOW FIGURE 50 9 Blood clotting occurs after injury to a blood vessel Exposure to collagen Platelets respond to injured tissue causing the liver to release clotting factors Prothrombin is converted to thrombin Thrombin cleaves fibrinogen Creates fibrin threads Fibrin threads and platelets form clots Plasma oozes through scab Exchange of materials happens in capillary beds using filtration osmosis and diffusion Arteries arterioles Have a much thicker layer of smooth muscle Have