The Cardiovascular System

1. The Cardiovascular System • Your Heart and Stuff

2. The Cardiovascular System • includes the heart, blood vessels, and blood. • Cardiology- the study of the heart and the diseases associated with it.

3. Functions • to supply cells & tissues with oxygen • to circulate substances & nutrients • to remove wastes (CO2 & urea) from cells and tissues.

4. Heart Coverings Pericardium – covers the heart, has 3 layers • Fibrous pericardium - outermost • Parietal pericardium - middle • (Pericardial cavity) • Visceral pericardium (continuous with epicardium) - innermost

6. The Heart Wall (3 layers): • epicardium (visceral pericardium) – reduces friction • myocardium - cardiac muscle tissue (bulk of heart) • endocardium – smooth inner lining of heart chambers and valves.

8. Heart Chambers • The upper chambers – atria (atrium) blood flows here 1st. Pumps to ventricles • The lower chambers – ventricles, pump blood out to body or lungs. • The right side of your heart receives blood (deoxy) from the body and pumps it to the lungs. • The left side of the heart receives blood (oxy) from the lungs and pumps it out to the body • A solid wall-like septum separates the atrium and ventricle on the right from those on the left – so blood on one side never mixes with blood on the other side

9. Why is this the right side? And this the left?

10. Heart Valves • Tricuspid Valve –btwn RA and RV • Pulmonary Valve –allows blood to leave RV • Pulmonary means lungs. • Bicuspid (mitral) Valve – btwn LA and LV • Aortic Valve – allows blood to leave LV

12. What color is blood? • Blood when oxygenated is red • However, deoxygenated is not blue as believed. It is actually a redish purple. • It appears blue because the color is diffused looking through the skin • This is also why veins typically appears almost green in African-Americans.

13. Blood Flow • Blood low on O2 (deoxygenated) enters Right Atrium through the superior and inferior venaecavae and coronary sinus • Right Atrium wall contracts, and blood passes thru tricuspid valve into Right Ventricle (only adds 30% of vol. to RV) • Right Ventricle contracts, and blood is forced thru pulmonary valve into pulmonary trunk divides into pulmonary arteries(left & right)to lungs

14. Blood Flow cont. • pulmonary arteries take blood to lungs; gas exchange occurs between blood and air in alveoli • Carbon Dioxide is released. Oxygen is taken in. Blood goes from deoxygenated to oxygenated • Freshly oxygenated blood returns to heart thru the pulmonary veins that lead to Left Atrium

15. Blood Flow cont. • Left Atrium wall contracts, and blood moves thru bicuspid valve into Left Ventricle • Left Ventricle contracts, blood moves thru aortic valve and into the aortaaorta carries oxygenated blood to tissues • Oxygen to tissues, Carbon Dioxide made in tissues released into blood • Deoxygenated blood is sent back to heart thru superior and inferior vena cava

18. Heart Sounds • Heart sounds are produced by vibrations in the tissue associated with the closing of the valves. • The first part of the heart sound (lubb) is heard during ventricular contraction when the valves between the Atrium & Ventricles closes. • The closing causes the blood to stop flowing or back up causing a sound almost like waves crashing on a beach. They do not make a sound until they crash. Blood does not make a sound when flowing; only when it is stopped and crashes into heart valve.

19. Heart Sounds cont’d • The second part of the heart sound (dubb) happens during ventricular relaxation when the pulmonary and aortic valves snap shut • Heart sounds give doctors an indication of how well the valves are functioning (ex: murmurs) • Mitral Valve prolapse is usually identified by lubb-dubb-squish. The squish is the valve closing improperly and some blood still is leaking through.

20. National geographic website • Here the heart Hit next twice

21. Cardiac Muscle fibers • Cardiac fibers are highly branched, so when any part of the network is stimulated, the whole unit contracts (called a functional syncytium) • There are 2 syncytia – the atrial syncytium and the ventricular syncytium

22. Conduction of a cardiac impulse: • Starts at the sinoatrial (S-A) node located in the RA • The S-A node is self-exciting (no outside stimulation needed) and is rhythmic (initiates 70-80 impulses/min. in an adult) • Called the “pacemaker”

23. Conduction of a cardiac impulse: • impulse generated by the S-A node causes the atrial syncytium to contract • impulse then travels to the atrioventricular (A-V) node located in the septum that separates the atria

25. Conduction of a cardiac impulse: • impulse is delayed as it passes thru the A-V node, allowing time for the atria to empty and the ventricles to fill with blood • impulse then travels thru a bundle of fibers called the bundle of His located in the interventricular septum.

26. Conduction of a cardiac impulse: • The bundle of His gives rise to Purkinje fibers • The Purkinje fibers extend down into the apex of the heart and curve upward thru the walls of the ventricles • As impulse passes thru Purkinje fibers it stimulates the ventricular syncytium to contract • Ventricles squeeze up from the bottom of V to squeeze blood out of heart.

28. Blood vessels • Arteries • carry blood away from heart; strong, thick; carry blood under high pressure; composed of mainly smooth muscle tissue • Not always oxygenated blood. Pulmonary artery takes deoxygenated blood to lungs away from heart. • Are typically deeper than veins • Arteries subdivide into smaller tubes called arterioles.

29. Blood vessels cont’d • Capillaries • are the smallest blood vessels. They connect the arterioles with the venules. • Capillary walls are thin enough to allow substances to pass through such as O2 & CO2 • Capillaries are microscopic and are only big enough for one red blood cell to go through at a time. If you can see it; it is not a capillary. • 10-40 billion capillaries in your body • No cell is 1/100 of cm from a capillary

30. Blood vessels cont’d • Veins • Venules are small vessels that merge to form veins; parallel to arterioles • these vessels carry blood back to heart and are not always deoxygenated. • Venules and veins have thinner walls than arteries because the blood pressure is less.

32. The Cardiac Cycle • The series of events that constitute a heartbeat • The atrial walls contract; the ventricle walls are relaxed • The ventricle walls contract; the atrial walls relax • Both the atria and the ventricles relax • Ventricle contractions control blood pressure • Contracting – systole • Relaxation - diastole

35. Blood Pressure • The force blood exerts against the inner walls of blood vessels • Usually refers to the pressure in the arteries supplied by the aorta • When the ventricles contract blood moves into the aorta and pulmonary trunk, increasing pressure • maximum pressure during ventricular contraction is called the systolic pressure

36. Blood Pressure • When ventricles relax, arterial pressure drops • The lowest pressure before the next ventricular contraction is called the diastolic pressure • If there’s a drop in blood pressure, walls of veins constrict, helping to maintain blood pressure by returning more blood to heart. (Less blood in veins if veins are smaller) • This ensures a nearly normal blood flow even when as much as 25% of blood volume is lost.

37. Taking Blood Pressure • Normal Blood Pressure 120/80. • Increase blood pressure until can not hear any flow because artery closed. Cuff pressure is greater than systole & diastole so blood vessels closed all the time. (Contraction & Relaxation)

38. Taking Blood Pressure • Let blood pressure come down until under 120. During Systole (contraction), pressure in arteries is greater than cuff, so artery open only during systole • But during diastole (relaxation) pressure of cuff is greater than pressure in blood vessels so blood vessels are closed.

39. Taking Blood Pressure • The walls of the blood vessels go in and out causing turbulent flow of blood. • Can hear turbulent flow because walls of arteries going in and out do to change in pressure. • Under 80 silent because cuff pressure less diastole pressure so arteries stay open. • Blood pressure always recorded as systolic = 120 diastolic 80

41. Pulse Rate • The pulse rate is equal to the rate at which the ventricles contract or equal to heart rate. • The pulse is the alternate expanding and recoiling of the artery walls.

42. Pulse

43. Blood vessel disorders • Arteriosclerosis- degenerative disease in which the arteries lose elasticity; the vessels become brittle and can rupture easily; associated with fatty diet, genetics, lack of exercise, cigarette smoking, etc. • Go to Heart Attack Then Blocking the Artery to watch video

44. Arteriosclerosis

45. Blood vessel disorders • Aneurysm- a bulge in a blood vessel; this area of the blood vessel then weakens and may burst; can result from trauma, high blood pressure, infections, or genetic defects

46. Aneurysm

47. Varicose veins- irregular dilations in superficial veins, especially of the legs; associated with prolonged increased back pressure, also with crossing legs. Blood vessel disorders cont’d

49. Hypertension – high b.p.; caused by kidney disease, high Na+ intake, obesity, stress, arteriosclerosis; left ventricle works overtime so myocardium thickens, enlarging heartcoronary vessels can’t feed overgrowth so parts of heart die Blood vessel disorders cont’d

50. Disorders, cont. • Anemia – condition in which the oxygen carrying capacity of the blood is reduced; symptoms: fatigue, intolerance to cold, and paleness. • Nutritional Anemia – inadequate diet, especially lacking in iron and vitamin B12 • Sickle-Cell Anemia – abnormal kind of hemoglobin results in cells shaped like a sickle (bent); they can rupture easily and often get stuck together; (genetic)