Cardiovascular system ► The heart pumps at approximately 70 times to pump about 5 liters of blood a minute. ► That is about 100,800 times each day. ► In 70 years this amounts to about 2.6 billion beats!

Functions ► Nutrients delivered ► Carries away waste ► Transport ► defense ► clotting ► Distributes heat

Evolution ► Prokaryotes/protists  Use simple diffusion/active transport/endo & exocytosis  Direct exchange w/ water

Evolution cont… ► Open circulatory systems ► Closed circulatory systems

Invertebrates ► Cnidarians (hydra, jellyfish)  Gastrovascular cavity  Central canal  Nutrients have only a few layers of cells to diffuse through

Invertebrates cont… ► Earthworms(annelids)  Separate digestive system & closed circulatory system  Primitive heart  hemoglobin

Invertebrates cont… ► Insects  Open circulatory system ► Hemolymph, hemocoel ► Does not transport O2 ► Long, thin-walled hearts

Vertebrate systems ► All have closed circulatory systems ► Strong well-developed hearts ► Capillaries, arteries & veins specialized for delivering blood

Vertebrate Hearts ► 2 types of chambers  Atria  Ventricles ► Myocardium ► Pericardium ► Endothelium ► ns/heart/heart_middle_frames.htm ns/heart/heart_middle_frames.htm ns/heart/heart_middle_frames.htm

Heart evolution-fish ► Single circulation ► 1 atrium, 1 ventricle  Atrium  vent  gills  cells  veins ► Very low pressure, limited metabolic rate

Amphibian heart ► Double circulation ► 3 chambers  2 atria  1 ventricle

Reptile Heart ► Double circulation ► 4 chambers-  2 atria, 2 ventricles ► septum

Mammalian Heart ► Double circulation ► 4 chambers  2 atria, 2 ventricles ► Highest pressure & metabolic rate

T Deoxy blood To lungs Deoxy blood from upper body Deoxy blood from vena cava Oxy blood from lungs Pulmonary valve Deoxy blood from lower body Most muscular part Pumps blood to entire body via aorta tricuspid Oxy blood to body Oxy blood from lungs Aortic valve Mitral valve/bicuspid valve

Both chambers relaxed Blood fills both chambers “dup” sound as blood slaps against closed SL valves Atria contract, forcing Remaining blood into ventricles Vents contract as SL Valves open Blood forced into aorta & pulm. Arteries “lub” sound as blood slaps Against AV valves The Cardiac Cycle Lub-dup, lub-dup

► Pulse ► Heart rate ► Cardiac output-(liters/min)  Heart rate x stroke volume (Beats/min) (liters/beat) ► 5L/min is avg. ►

Control of Heart Rhythm 1% of heart cells are autorhythmic Bundle of His

P wave Indicates atrial depolarization, or contraction of the atrium. QRS complex Indicates ventricular depolarization, or contraction of the ventricles. T wave Indicates ventricular repolarization