Cardiovascular System

1. Cardiovascular System

2. Characteristics of Blood • Connective tissue • Plasma and cells • Transports substances between body cells and the external environment

3. Blood Volumes • Varies with body size, fluid and electrolyte concentrations, and amount of adipose • Average adult volume – 5 liters (4-5 L for women, 5-6 L for men) • Hematocrit – usually 45%

4. Blood Cell Types • Erythrocytes – RBCs • Leukocytes – WBCs • Thrombocytes - platelets

5. Red Blood Cells (RBCs) • Biconcave disks that thin near the centers  increased surface area for transporting gases • Have nuclei early in development, but extrude them • No nucleus – more room for hemoglobin, but cannot reproduce or make proteins

6. Hemoglobin • Oxygen-carrying protein • 1/3 of each RBC • Gives blood its color • Oxyhemoglobin • Deoxyhemoglobin • Hypoxia • Cyanosis

7. Red Blood Cell Counts • RBCC – the number of RBCs in 1 mm3 of blood • Adult male average – 4.6 – 6.2 million • Adult female average – 4.2 – 5.4 million • Determines blood’s oxygen carrying capacity • Important diagnostic tool

8. Blood Cell Production • RBCs are normally flexible, elastic, and able to pass through small blood vessels • More fragile as they age • Macrophages phagocytize and destroy damaged RBCs in the liver and spleen

9. Breakdown of Hemoglobin

11. White Blood Cells (WBCs) • Function to protect against disease • Phagocytize bacterial cells • Produce antibodies • Move by diapedesis • 2 main types: • Granulocytes – neutrophils, eosinophils, and basophils • Agranulocytes – monocytes and lymphocytes

13. Granulocytes • Lobed nucleus with 2-5 sections • Dark staining nucleus and pale granules • 54-62% of WBCs • Contain many lysosomes – actively phagocytizes bacteria

14. Granulocytes • Contains coarse, uniformly sized granules • 2 lobes on nucleus • Stains red • 1-3% of WBCs • Kills parasites • Helps control inflammation and allergic reactions

15. Granulocyte • Fewer, more irregular granules than eosinophils • Granules stain deep blue • Less than 1% of WBCs • Contain heparin (inhibits blood clotting) and histamine (increases blood flow to injured tissues)

16. Agranulocytes • Largest blood cells • May live weeks months • 3-9% of WBCs • Discussed later

17. Agranulocyte • Form in red bone marrow and lymphatic system • Slightly larger than RBCs • Large, round nucleus with rim of cytoplasm • May live for years • 25-33% of WBCs • Discussed more later

18. White Blood Cell Count (WBCC) • Number of WBCs in 1 mm3 of blood • Adult average – 5000 – 10,000 cells • Leukocytosis • Leukopenia • Differential WBCC (DIFF) • More neutrophils – bacterial infection • More eosinophils – parasitic infection, allergic reaction • Leukemia

19. Platelets • Not complete cells • Form from megakaryocytes that fragment • Lack nuclei • Half size of RBCs • Live 10 days • Average count – 130,000 – 360,000 cells • Help close breaks in damaged blood vessels • Initiate formation of blood clots

20. Plasma • 92% water • Functions include: • Transporting nutrients, gases, and vitamins • Regulating fluid and electrolyte balance • Maintaining pH

21. Plasma Proteins

22. Hemostasis • Vasospasm • Platelet plug formation • Coagulation • Fibroblasts invade clot

23. Hemostasis

24. Blood Groups • ABO blood group is based on the presence or absence of 2 major antigens (RBC surface molecules) • 4 possible combinations: • A • B • AB • O

26. Rh Blood Group

27. Cardiovascular System – Pulmonary and Systemic Circuits

28. System Overview • System consists of the heart and the blood vessels • Function: to bring oxygen and nutrients to all body cells and to remove waste

30. Heart Location

31. Coverings of the Heart • Pericardium • Fibrous pericardium • Parietal pericardium • Visceral pericardium • Pericardial cavity • Pericardial fluid reduces friction

32. Walls of the Heart • Epicardium • Myocardium • Endocardium • Purkinje fibers

33. Heart Chambers • 4 chambers of the heart • Atria • Thin walls • Receive blood returning to the heart • Auricles • Ventricles • Thicker walls • Receive blood from atria • Force blood out of heart • Septum

35. Heart Valves • Atrioventricular valves • Tricuspid – right • Bicuspid – left • Semilunar valves • Pulmonary – right • Aortic – left • Chordae tendinae • Papillary muscles

37. Blood Supply to the Heart • Coronary arteries • Cardiac veins • Coronary sinus

41. Cardiac Cycle • Cardiac cycle – series of events that constitute a complete heartbeat • Systole – contraction • Diastole – relaxation

42. Cardiac Cycle • Heart Sounds – “lub-dup” • Lub – ventricular systole • AV valves close • Dup – ventricular diastole • SL valves close • Murmur

43. Cardiac Conduction System • Coordinates the events of the cardiac cycle • Consists of clumps and strands of specialized cardiac muscle that initiate and distribute impulses throughout the myocardium

44. Nodes of Cardiac Conduction System • Sinoatrial node – AKA “pacemaker” • Just beneath epicardium • Located in right atrium near opening of superior vena cava • Initiates impulses without nervous stimulation

45. Nodes of Cardiac Conduction System • Atrioventricular node • Located in inferior portion of septum • AV bundle (bundle of His) • Large fibers run through the interventricular septum • Purkinje fibers • Spread from septum into papillary muscles • Stimulate ventricular contraction

47. Regulation of Cardiac Cycle • Parasympathetic and sympathetic fibers from medulla oblongata run to the nodes • Secrete acetylcholine to decrease heart rate • Secrete norepinephrine to increase heart rate • Cardiac center

48. Electrocardiogram (ECG) • Recording of the electrical changes in the myocardium during the cardiac cycle • P – atrial systole • QRS – ventricular systole; covers atrial diastole • T – ventricular diastole

49. Blood Vessels

50. Arteries • Strong, elastic vessels that carry blood away from the heart • Lead to finer branches called arterioles