BIOL 152 1st Edition Lecture 21 Outline of Last Lecture Animal Nutrition Outline of Current Lecture Circulation Current Lecture Circulation Circulatory Systems Transport systems that circulate fluid blood or interstitial fluid between cells and the exchange organs i e gills and lungs Diffusion not efficient over large distances Circulatory system solves this problem Gastrovascular Cavity Cnidaria Platyhelminthes Open circulatory system 3 components Hemolymph bathes organs directly Less expensive Closed circulatory system Same 3 components Blood confined to vessels More efficient for larger active species Vertebrate Cardiovascular system Two to four chambers These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute o o o o o o o o Atria Ventricles Vessels Arteries Arterioles Capillaries beds Venules Veins Variations on general theme Number of chambers and circuits 2 3 4 Number of circuits 1 2 The anatomy of the mammalian heart The pathway Right ventricle pumps O2 poor blood to lungs through the pulmonary arteries O2 rich blood returns to the heart in pulmonary veins to the left atrium Left ventricle pumps O2 rich blood into systemic circuit via the aorta O2 poor blood returns from body in anterior and posterior vena cava which drain into the right atrium The anatomy of the mammalian heart Valves flaps of connective tissue prevent backflow of blood o Atrioventricular AV valves o Between atria and ventricles o Closes with ventricle contraction Semilunar SL valves at exits of heart aorta and pulmonary artery close with ventricle relaxation The Cardiac Cycle One sequence of contraction and relaxation Systole is contraction Diastole is relaxation Maintaining the heart s rhythmic beat Myogenic versus neurogenic heart Sinoatrial node pacemaker initiates electrical impulses to stimulate contraction Branching cardiac muscle and intercalated discs allow impulse to spread quickly Atrioventricular node delays ventricular contraction slightly to allow ventricles to fill Electrocardiogram EKG Factors affecting heart rate Hormones Body temperature Exercise
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