CARDIOVASCULAR SYSTEM

1. CARDIOVASCULAR SYSTEM

2. Objectives • List the functions of the circulatory system • Describe the heart • General features, chambers, valves • Differentiate between the three types of bv’s • Describe the two circulations • Pulmonary vs. Systemic • Explain how blood pumps through the heart • Define ECG and what P wave, QRS wave and T wave represent

3. Structure and Function • Functions of the cardiovascular system: • Transports nutrients and oxygen to the body • Transports waste products from the cells to the kidneys for excretion • Distributes hormones and antibodies throughout the body • Helps control body temperature and maintain electrolyte balance

4. General features of heart • Two-sided, double pump • Weighs less than a pound • Slightly bigger than a fist • Located between the lungs in the thoracic cavity • Positioned partially to the left of the sternum

5. Heart Anatomy •Four chambers of the heart • Atria • Top two chambers • Blood enters the heart through the atria • Ventricles • Lower two chambers • Blood leaves the heart through the ventricles • Septum • Divides the right and left sides of the heart

6. Heart Anatomy • Two atria • Two ventricles

7. Heart Anatomy cont. •Four valves of the heart • Prevent blood from flowing back into heart • Atrioventricular • Allow blood to pass from the atria to ventricles • Semilunar valves • Allow blood to pass out of the heart • Separate the ventricles from the pulmonary artery and aorta

8. Heart Anatomy cont. • Atrioventricular valves • Tricuspid/right AV valve • 3 flaps • Bicuspid/mitral/left AV valve • 2 flaps • Semilunar valves

9. Blood Vessels • The cardiovascular system has three types of blood vessels: • Arteries (and arterioles) – carry blood away from the heart • Capillaries – where nutrient and gas exchange occur • Veins (and venules) – carry blood toward the heart.

10. Blood Vessels (Continued) • Arteries • Carry blood away from the heart • Blood is oxygenated • Have a muscular layer of tissue that helps pump blood out of the body • Aorta is the largest artery in the body, which branches into smaller arteries • Arterioles • Smaller vessels • Blood moves from arterioles to capillaries

11. Blood Vessels (Continued) • Capillaries • Microscopic vessels that carry blood between the arterial and venous vessels • Gases, nutrients, and waste exchanged • Blood gives up oxygen • Blood flows from capillaries into venules

12. Blood Vessels (Continued) • Veins • Venues branch together to form veins • Carry blood back to the heart by gravity • Blood is deoxygenated except for pulmonary vein • Contain values that prevent blood from flowing back • Have a much thinner muscular layer • Superior vena cava and inferior vena cava • Largest veins

13. Blood Vessels

14. Circulation • Pulmonary circulation • Right side of heart pumps deoxygenated blood to the lungs • Systemic circulation • Left side of the heart pumps oxygenated blood to rest of the body • Blood returns to the right side of the heart from the body to complete the cycle • Hepatic circulation • Path of the blood from the intestines, gallbladder, pancreas, stomach, and spleen through the liver

15. Passage of Blood Through the Heart • Blood follows this sequence through the heart: superior and inferior vena cava → right atrium → tricuspid valve → right ventricle → pulmonary semilunar valve → pulmonary trunk and arteries to the lungs → pulmonary veins leaving the lungs → left atrium → bicuspid valve → left ventricle → aortic semilunar valve → aorta → to the body.

16. Structures of the Heart

17. Path of blood through the heart

18. Figure 11-1 Blood Flow Through the Cardiovascular System

19. Internal view of the heart

20. Cardiac cycle animation • Bill Nye

21. The Heartbeat • Each heartbeat is called a cardiac cycle. • When the heart beats, the two atria contract together, then the two ventricles contract; then the whole heart relaxes. • Systole is the contraction of heart chambers; diastole is their relaxation. • The heart sounds, lub-dup, are due to the closing of the atrioventricular valves, followed by the closing of the semilunar valves.

22. The Heartbeat (Continued) • Heart is the only muscle that can stimulate its own contractions • Sinoatrial cells (SA node or pacemaker) in right atrium • Initiates the heartbeat and causes the atria to contract on average every 0.85 seconds • Atrioventricular node (AV node) • Sends impulse into lower portions of the heart (ventricles) • The signal for ventricles to contract travels from AV node to through the atrioventricular bundle to the smaller Purkinje fibers

23. Intrinsic Control of Heartbeat • The SA node sends out a stimulus, which cause the atria to contract. • When this stimulus reaches the AV node, it signals the ventricles to contract. • Impulses pass down the two branches of the atrioventricular bundle to the Purkinje fibers, and thereafter the ventricles contract

24. Path of Electrical Current in the Heart

25. Extrinsic Control of Heartbeat • A cardiac control center in the medulla oblongata speeds up or slows down the heart rate by way of the autonomic nervous system branches: parasympathetic system (slows heart rate) and the sympathetic system (increases heart rate). • Hormones epinephrine and norepinephrine from the adrenal medulla also stimulate faster heart rate.

26. The Electrocardiogram • An electrocardiogram (ECG) is a recording of the electrical changes that occur in the myocardium during a cardiac cycle. • Atrial depolarization creates the P wave, ventricle depolarization creates the QRS wave, and repolarization of the ventricles produces the T wave.

27. Electrocardiogram • The P wave occurs just prior to atrial contraction • The QRS complex occurs just prior to ventricular contraction • The T wave occurs when the ventricles are recovering from contraction.

28. Heart dissection on cadaver

29. Figure 11-5 Principal Arteries and Veins

30. Assessment Techniques • Measuring pulse and blood pressure • Listening to heart sounds • Determining cardiac output

31. Pulse Surge of blood against the walls of the arteries Eight pulse points on the body Normal pulse rate for adults is 60 to 90 beats per minute Blood pressure Force of blood against the walls of the arteries Systolic pressure Ventricles of the heart contract Diastolic pressure Ventricles relax Normal blood pressure 120/80 Blood pressure varies greatly among people Assessment Techniques (Continued)

32. Figure 11-6 Peripheral Pulse Points

33. Assessment Techniques (Continued) • Heart sounds • Heard through a stethoscope • Murmurs • Abnormal or extra sound • Classified by timing, intensity, location, pitch, and quality of the sound • May be benign or indicate a disorder • Thrill • Vibration felt by touch over an artery • Caused by an abnormal flow of blood

34. Assessment Techniques (Continued) • Electrocardiogram • Measures graphically the pattern of electrical activity in heart contractions • Normal and abnormal heart activities have characteristic wave patterns • Echocardiography • Uses ultrasonic waves to show the structures and motions of the heart • Transducer plots the sound echoes to produce a graphic picture

35. Assessment Techniques (Continued) • Cardiac catheterization • Used to measure the pressure in the chambers of the heart, to take blood samples, and to view obstructions in the vessels • A tube is inserted through the blood vessels into the heart • Dye is then released and traced using x-ray

36. Oxygen transport

37. Blood

38. Blood • Essential Life Supportive Fluid • Transported in Closed System Throughout Body Through Blood Vessels • Connective Tissue = Cells + Matrix

39. Physical Characteristics • Viscous • pH 7.35 – 7.45 • Temperature: 38 degrees C; 100.4 degrees F • 7% - 8% of total body weight • Males: 5 – 6 liters • Females: 4 – 5 liters

40. Functions of Blood • Transportation • Regulation • Protection

41. Formed Elements • Erythrocytes: (RBCs) – are produced in the red bone marrow. • Leukocytes: (WBCs) – they are formed in the bone marrow and lymph tissue. • Platelets: (Thrombocytes) – are the fragments or pieces of cells because they lack nuclei and vary in shape

42. General Characteristics of Formed Elements • Living blood cells • 2 out of 3 are NOT true cells • Most are short lived • Most do not divide • Hematopoiesis occurs in liver, spleen, thymus, & bone marrow

43. Plasma • Liquid portion: 90-92% water with fibrous proteins (fibrin) • Straw colored, sticky fluid

44. Plasma • Proteins • Non-protein nitrogenous substances: • Nutrients • Electrolytes • Respiratory gases

45. Functions of Plasma • Suspends blood cells & transports blood cells • Carries metabolic wastes & nutrients • Circulates hormones Maintains water content and body temperature • Maintains acid-base balance of blood

46. Erythrocytes • Shape: biconcave disc • Spectrin (fibrous protein)  flexibility to change shape • Mature  anucleate • 4 – 5.5 million per cubic millimeter • Lifespan: 100 – 120 days • 97% is hemoglobin • Erythropoiesis

47. Leukocytes/WBCs Surveillance, Fighters, Protectors

48. 5 Types of WBCs • Neutrophils: granulocyte • Lymphocyte: agranulocyte • Monocyte: agranulocyte • Eosinophil: granulocyte • Basophil: granulocyte

49. Neutrophils • Phagocytize bacteria by secreting an enzyme called lysozyme

50. Monocytes • Phagocytize bacteria and foreign materials