Circulation System DITTO December 14, 2011 Aim: Circulatory System in Animals Warm-up: What happens to your heart rate when you exercise? HW: Circulation System DITTO

Feeding Energy Needs Why do we need a circulatory system? supplies in fuel (sugars) digestive system oxygen respiratory system waste out CO2 need to pick up & deliver the supplies & wastes around the body circulatory system

Simple organisms When your body is only 2-cell layers thick, you can get supplies in and waste out just through diffusion all cells within easy reach of fluid Jellyfish Hydra

Complex organisms Circulatory system made up of 3 parts organ heart tissues & cells blood vessels arteries veins capillaries blood red blood cells plasma

Circulatory systems All animals have: muscular pump = tubes = heart circulatory fluid = heart Blood vessels blood

Human Heart 4-Chambered heart atria (atrium) ventricles thin wall collection chamber receive blood ventricles thick wall pump 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 prevent backflow Heart sounds closing of valves Makes “Lub” and “Dub” sound Heart murmur leaking valve causes hissing sound 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 = EKG

Cardiac Cycle How is this reflected in blood pressure measurements? ventricles fill How is this reflected in blood pressure measurements? Systolic ________ Dystolic 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. chambers fill pump (peak pressure) _________________ fill (minimum pressure) 120 ________ 80 ventricles pump

Measurement of blood pressure if systolic > 150 or if diastolic > 90 hypertension = (high blood pressure)