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Cardiovascular System

Cardiovascular System

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Cardiovascular System

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  1. CardiovascularSystem Circulation and Gas Exchange

  2. Circulation • Exchange of materials must take place across a wet membrane

  3. Simple animals have a gastrovascular cavity (digestion and circulation) Phylum Cnidaria: gastrovascular cavity

  4. Circulation • Complex organisms are multi-layered & have cells that are isolated and need transport systems • Special organs just for transport (circulation); heart, vessels

  5. Circulatory System Overview: • Open vs closed • Types of hearts in vertebrates • Double circulation • Structure and function of basic parts: • Heart, vessels, blood

  6. Open Circulatory System • No closed vascular tubes; ‘Blood’ (hemolymph) circulates freely in sinuses (spaces around organs) • Hydrostatic pressure returns the hemolymph to the heart • Ex. Arthropods, clams; limited in size

  7. Closed Circulatory System • Closed vessels; veins • Blood travels to an exchange surface (pulmonary), then to body cells (systemic) • Blood remains in vessels; • Much more efficient • Ex. Earthworms, vertebrates

  8. Closed Open

  9. Vertebrate Phylogeny Adaptations (Evolution) of the Cardiovascular System

  10. Structural Adaptations • Heart has chambers • Atria - Superior chambers - receive blood • Ventricles - Inferior chambers; pump blood away from the heart

  11. Vertebrate Hearts • Number of chambers is different, demonstrate evolutionary adaptation • 2 chambers = 1atrium, 1ventricle • 3 chambers = 2atria, 1ventricle • 4 chambers = 2atria, 2ventricles

  12. Blood passes through 2 capillary beds; pulmonary, (gill) systemic • Reduces blood pressure • Oxygen-rich blood slower to circulate

  13. Three ChamberedHeart • Double circulation:blood travels separately to lungs and system • Oxygenated blood mixes with deoxygenated blood • Amphibians, reptiles

  14. Double circulation; pulmonary and systemic are separated

  15. Mammalian Heart 4-chambered, double circulation

  16. Systemic circuit Pulmonary circuit Systemic circuit

  17. 4 chambered: efficient, double circulation, homeothermic, lots of energy; ex. Mammals, birds

  18. Structure and Function of the Circulatory System • Three basic parts: • Heart • Blood vessels • Blood

  19. Heart • Cardiac muscle; Smooth (rhythmical, persistent) + striated (multinucleated, strength) • Muscle tissue can change shape, in response to electrical or chemical stimulation

  20. Heart Structure • Pericardium = sac that surrounds the heart (?) • 2 Atria; thin walled, receive blood, no pressure, right/left side • Right - receives systemic blood (‘deox’) • Left - receives blood from lungs (‘oxed’)

  21. Heart Structure • 2 Ventricles; thicker walls, pump blood to body/lungs, • Right - pumps blood to lungs (pulmonary) • Left - pumps blood to body (systemic); heaviest muscle

  22. Blood Flow Through the Heart

  23. 4. O2 rich blood to body 2. O2 poor blood to lungs 3. O2 rich blood from lungs 1. O2 poor systemic blood

  24. Cardiac Cycle • Heart cycle: sequence of events during heartbeat • Systole • Diastole

  25. Systole • Heart contraction • Chambers ‘pump’ blood • Atria contract first (0.1 seconds); atrial systole • Ventricles contract; force blood into arteries; ventricular systole

  26. Diastole • Relaxation phase • Ventricles refill with blood • Valves prevent ‘backflow’

  27. Heart Cycle • Heart Rate = pulse; number of beats per minute • Avg. = 65-70/min. at rest • Stroke volume amount of blood that the left ventricle pumps systemically per minute; • Average human = 75 ml

  28. Cardiac Output • Rate x volume • vol. = 75ml • 70 ‘beats’ /min. • 75 ml x 70 = 5.25 l • 70/min. x 60 x 24 x 365 x 70 = • A lot

  29. Heart Cycle Inverse relationship between size and heart rate; Elephants = 25 Shrews = 1560 25 1560

  30. How Do We Keep Blood From Going ‘Backwards’? One-Way Valves

  31. Structure • Four valves: prevent ‘back flow’ • 2 Atrioventricular between atria and ventricles • 2 Semilunar; between ventricles and arteries, aorta and pulmonary

  32. Atrioventricular valves Left atrium Right atrium Bicuspid(mitral valve) MVP Tricuspid(‘three points’) Left Ventricle Right ventricle

  33. 2 Semilunar; between ventricles and arteries Aortic valve Pulmonary valve LV RV

  34. Heart Cycle • Heart sounds: valves opening/closing; “heart beat” • Stethoscope • “Lubb” = lower pitch, atrioventricular valves closing (bicuspid/tricuspid); ventricles contracting; just before systole • “Dupp” = semilunar valves closing; ventricles relax; just before diastole

  35. Heart Cycle • Heart Murmur:defect in valve causing backflow. Serious, corrected with surgery Normal Murmurs

  36. Control of the Heart Cycle

  37. Control of Heart Cycle • Intercalated disks = special areas between cells; extraordinary cell-to-cell communication; folds in between like tongue-in-groove • (Why is this important?) – structure/function

  38. Control of Heart Cycle • Cardiac muscle is myogenic (self-excitable) • Contracts without nervous input • Tempo is controlled by nodes (knots of nervous tissue + cardiac muscle) • Two ‘nodes’ stimulate muscle contraction • Sinoatrial Node (SA) • Atrioventricular node (AV)

  39. Sinoatrial node (SA) - tempo of contraction “Pacemaker” • Starts a wave of contraction; causes both atria to contract together

  40. Atrioventricular node (AV) • Impulse delayed 0.1 second (why) • Impulse travels to Purkinje fibers; cause apex of heart to twist, wringing all blood out

  41. Electrocardiogram • Detects tiny electrical changes; action potentials • Depolarization/repolarization detected by electrodes on surface of skin

  42. Length of time measurement indicates healthiness Protracted time = unhealthy heart Non-surgicalprocedure