Circulatory System in Animals Take a look at a skeleton and see how well a heart is protected — open heart surgery takes breaking a body to get to the heart. 2008-2009

Feeding Energy Needs Why do we need a circulatory system? supplies in _______________________ ______________________ waste out need to pick up & deliver the supplies & wastes around the body

Circulatory System Organ ______________ Tissues & cells

Vertebrate Heart 4-Chambered heart ____________ (atrium) ____________________ collection chamber receive blood __________________ pump blood out left atrium right atrium right ventricle left ventricle

Evolution of circulatory system Not everyone has a 4-chambered heart fish amphibian reptiles birds & mammals 2 chamber 3 chamber 3 chamber 4 chamber A powerful four–chambered heart was an essential adaptation in support of the endothermic way of life characteristic of mammals and birds. Endotherms use about ten times as much energy as equal–sized ectotherms; therefore, their circulatory systems need to deliver about ten times as much fuel and O2 to their tissues (and remove ten times as much CO2 and other wastes). This large traffic of substances is made possible by separate and independent systemic and pulmonary circulations and by large, powerful hearts that pump the necessary volume of blood. Mammals and birds descended from different reptilian ancestors, and their four–chambered hearts evolved independently—an example of convergent evolution. Why is it an advantage to get big? Herbivore: can eat more with bigger gut. lowers predation (but will push predators to get bigger as well, although no one east elephant s.) V A A A A A A A V V V V V

Lub-dub, lub-dub 4 valves in the heart Heart sounds Heart murmur flaps of connective tissue ___________________________ Heart sounds “Lub” force blood against closed AV valves “Dub” force of blood against semilunar valves Heart murmur _________________________________________ blood squirts backward through valve SL AV AV

Electrical signals heart pumping controlled by electrical impulses stimulates ventricles to contract from bottom to top, driving blood into arteries allows atria to empty completely before ventricles contract heart pumping controlled by electrical impulses signal also transmitted to skin = ________

atria empty into ventricles fill (minimum pressure) Cardiac Cycle How is this reflected in blood pressure measurements? chambers begin to fill pump (peak pressure) __________________ fill (minimum pressure) The cardiac cycle. For an adult human at rest with a pulse of about 75 beats per minute, one complete cardiac cycle takes about 0.8 second. During a relaxation phase (atria and ventricles in diastole), blood returning from the large veins flows into the atria and ventricles. A brief period of atrial systole then forces all remaining blood out of the atria into the ventricles. During the remainder of the cycle, ventricular systole pumps blood into the large arteries. Note that 7/8 of the time—all but 0.1 second of the cardiac cycle—the atria are relaxed and are filling with blood returning via the veins. 110 80 ______ ventricles pump

Measurement of blood pressure if top number > 150 or if bottom number > 90 hypertension = (high blood pressure)

Have a heart? Ask Questions!! 2006-2007