2. The Cardiovascular System (Introduction)
The body’s internal transport network
Includes the heart, blood, and blood vessels
Transports
Nutrients
Oxygen
Waste products
Chemical messengers

3. Functions of Blood (11-1)
Transports dissolved gases, nutrients, hormones, and metabolic wastes
Regulates interstitial fluid pH and ion composition
Restricts fluid loss at injury sites
Defends against toxins and pathogens
Stabilizes body temperature

4. Composition of Blood (11-1)
Liquid connective tissue
Contains cells (formed elements) suspended in a fluid matrix (plasma)
Formed elements include red blood cells, white blood cells, and platelets
Blood volume varies by average body size
Adult males average 5–6 liters
Adult females average 4–5 liters

5. Characteristics of Blood (11-1)
Temperature is 38ºC, slightly above body temperature
Blood is five times more viscous than water
Viscosity refers to thickness, stickiness, and resistance to flow
More viscous due to plasma proteins and formed elements
pH is slightly alkaline in a range of 7.35–7.45

6. Plasma (11-2)
Along with interstitial fluid, accounts for most of the volume of extracellular fluid (ECF)
Makes up about 55 percent of volume of whole blood
Contains:
Water (92%)
Plasma proteins (7%)
Other solutes (1%) which include hormones, nutrients, and gases

7. Erythrocytes or Red Blood Cells (11-3)
RBCs
Account for 99.9 percent of formed elements
Contain red pigment molecule hemoglobin
Transports oxygen and carbon dioxide
Hematocrit
Percentage of RBCs in whole blood
Hematocrit in men is 46 percent
Hematocrit in women is 42 percent

8. Structure of RBCs (11-3)
Specialized to transport oxygen and carbon dioxide
Unique biconcave shape provides advantages
Increased rate of diffusion Increased flexibility to squeeze through narrow capillaries
During RBC formation organelles are lost
Cannot go through cell division since they lack a nucleus
For energy, rely on anaerobic metabolism of glucose absorbed from plasma

9. Figure 11-2 The Anatomy of Red Blood Cells.

10. Hemoglobin Structure (11-3)
Hemoglobin (Hb) structure
Accounts for over 95 percent of all RBC intracellular proteins
Composed of two pairs of globular proteins, called subunits
Each subunit contains a heme, with an iron atom
Transports oxygen and carbon dioxide
Oxygen binds to heme
Carbon dioxide binds to the globin subunits

11. Anemia (11-3) Reduction in the blood’s oxygen-carrying capacity
Caused by:
Low hematocrit
Reduced hemoglobin content in RBCs
Symptoms include:
Muscle fatigue and weakness
General lack of energy

12. RBC Life Span and Circulation (11-3)
RBCs are exposed to stresses of friction and wear and tear
Bounce against walls of blood vessels
Squeeze through small capillaries
Life span is about 120 days
About 1 percent of all RBCs are replaced each day
About 3 million new RBCs enter circulation per second

13. Gender and Iron Reserves (11-3)
Men have about 3.5 g of iron (in the ionic form of Fe2+)
2.5 g of that is bound to Hb
Reserve of 1 g stored in liver and bone marrow
Women have 2.4 g of Fe2+
1.9 g in Hb
Reserve of only 0.5 g
Women often require dietary supplements
If inadequate, iron deficiency anemia may appear

14. RBC Formation (11-3) Also called erythropoiesis
In adults, occurs in red bone marrow
Requires amino acids, iron, and vitamins

15. Stages in RBC Maturation (11-3)
Embryonic cells differentiate into multipotent stem cells, called hemocytoblasts
Hemocytoblasts, or hematopoietic stem cells (HSCs), produce myeloid stem cells
Erythroblasts are immature and are synthesizing Hb
When nucleus is shed they become reticulocytes
Reticulocytes enter bloodstream to mature into RBCs

16. Figure 11-4 The Origins and Differentiation of Red Blood Cells, Platelets, and White Blood Cells.

17. Regulation of Erythropoiesis (11-3)
Stimulated by low tissue oxygen, called hypoxia
Kidney hypoxia triggers release of erythropoietin (EPO)
When anemia occurs
When blood flow to kidney decreases
When oxygen content of air in the lungs declines
When damage to respiratory surfaces occur
Speeds up rate of maturation of RBCs

18. Figure 11-5 The Role of EPO in the Stimulation of Erythropoiesis.

19. ABO Blood Types and Rh System (11-4)
Based on antigen–antibody responses
Antigens are substances that can trigger an immune response
Surface antigens on your body’s cells are considered normal, not foreign
Presence or absence of antigens on membrane of RBC determines blood type
Three major antigens are A, B, and Rh (or D)

20. Blood Types (11-4) Type A blood has antigen A only
Type B blood has antigen B only
Type AB blood had both A and B
Type O blood has neither A nor B
Rh antigen indicated by presence (Rh positive, or Rh+) or absence (Rh negative, or Rh–)
Blood types reported with positive or negative signs
Examples: O– or AB+

21. Figure 11-6a Blood Types and Cross-Reactions.

22. Table 11.1

23. Antibodies (11-4) Found in plasma
Will not attack your own surface antigens on your RBCs
Will attack foreign antigens on RBCs of different blood type
Type A blood contains anti-B antibodies
Type B blood contains anti-A antibodies
Type AB blood contains neither antibody
Type O blood contains both antibodies

24. Cross-Reactions in Transfusions (11-4)
Occur when antibodies in recipient react with their specific surface antigen on donor’s RBCs
Causes clumping of RBCs
Checking blood types before transfusions ensures the types are compatible

25. The Difference between ABO and Rh (11-4)
Anti-A or anti-B antibodies
Spontaneously develop during first six months of life
No exposure to foreign antigens needed
Anti-Rh antibodies in Rh-negative person
Do not develop unless individual is exposed to Rh- positive blood
Exposure can occur accidentally during a transfusion or during childbirth

26. Leukocytes, or White Blood Cells (11-5)
WBCs
Larger than RBCs
Help defend the body against invasion by pathogens
Remove toxins, wastes, and abnormal or damaged cells
Contain nucleus and other organelles
Lack hemoglobin
Number about 5000–10,000 per microliter of blood

27. Two Categories of White Blood Cells (11-5)
Granulocytes
Neutrophils, eosinophils, basophils
Agranulocytes
Lymphocytes and monocytes

28. WBC Circulation and Movement (11-5)
Four characteristics of circulating WBCs
All are capable of amoeboid movement
All can migrate outside of bloodstream through process called diapedesis
All are attracted to specific chemical stimuli, which guide them to pathogens; process is called positive chemotaxis
Neutrophils, eosinophils, and monocytes are phagocytes

29. Types of WBCs (11-5)
Neutrophils, eosinophils, basophils, and monocytes
Part of the body’s nonspecific defenses
Respond to any threat
Lymphocytes
Responsible for specific defenses
Respond to specific, individual pathogens

30. Neutrophils (11-5) Make up 50–70 percent of circulating WBCs
Have a dense, contorted multilobular nucleus
Usually first WBC to arrive at injury site
Very active phagocytes, attacking and digesting bacteria

31. Eosinophils (11-5) Make up 2–4 percent of circulating WBCs
Have granules that stain deep red and a two-lobed nucleus
Are phagocytic, but also attack through exocytosis of toxic compounds
Numbers increase during parasitic infection or allergic reactions
Release enzymes that reduce inflammation

32. Basophils (11-5) Somewhat smaller than neutrophils and eosinophils
Rare, less than 1 percent of circulating WBCs
Granules stain deep purple or blue
Release:
Heparin which prevents blood clotting
Histamine which dilates blood vessels

33. Monocytes (11-5)
About twice the size of a typical RBC with a large, kidney bean–shaped nucleus
Usually 2–8 percent of circulating WBCs
Migrate into tissues and become macrophages
Aggressive phagocytes
Figure 11-8d White Blood Cells.

34. Lymphocytes (11-5)
Slightly larger than typical RBC with nucleus taking up most of cell
About 20–40 percent of circulating WBCs
Large numbers migrate in and out of peripheral tissues
Some attack foreign cells, others secrete antibodies into circulation
Figure 11-8e White Blood Cells.

35. The Differential WBC Count (11-5)
Indicates the number of each type of cell in a sample of 100 WBCs
Provides information about type of disorder, infection, inflammation, or allergic reaction
Reduced numbers of WBCs is called leukopenia
Excessive numbers of WBCs is called leukocytosis
Leukemia
Cancer of blood-forming tissues
Indicated by extreme leukocytosis or by presence of abnormal or immature WBCs

36. Platelets versus Thrombocytes (11-6)
In nonmammalian vertebrates
Platelets exist as nucleated cells called thrombocytes
In humans
Platelets exist as cell fragments of enormous cells called megakaryocytes

37. Platelets (11-6)
Initiate clotting process and help close injured blood vessels
Circulate for 9–12 days
Normal count is 150,000–500,000/µL
Low count is called thrombocytopenia
High count is called thrombocytosis
Figure 11-1 The Composition of Whole Blood.

38. Three Phases of Hemostasis (11-7)
Hemostasis, or the stopping of bleeding
Halts the loss of blood through damaged vessels
Establishes framework for tissue repair
Three steps
​Vascular phase
​Platelet phase
​Coagulation phase

39. The Vascular Phase (11-7)
Blood vessels contain smooth muscle lined with endothelium
Damage triggers contraction in smooth muscle fibers (called vascular spasm)
Decreases vessel diameter
Slows or stops loss of blood through wall of small vessel
Endothelial cells at the site become “sticky”

40. The Platelet Phase (11-7) Occurs within 15 seconds of injury
Platelets attach to sticky endothelium and exposed collagen
More platelets arrive and stick to each other forming a platelet plug
May be enough to close a small break
Figure 11-9 The Vascular, Platelet, and Coagulation Phases of Hemostasis.

41. The Coagulation Phase (11-7)
Begins 30 seconds or more after damage
Involves complex sequence of steps, or cascade
End result is conversion of protein fibrinogen to insoluble fibrin
Fibrin mesh grows
Traps cells and more platelets
Forms a blood clot
Seals damaged portion of blood vessel

43. The Clotting Process (11-7)
Requires clotting factors
Calcium ions, vitamin K, and 11 different plasma proteins
Proteins are converted from inactive proenzymes to active enzymes involved in reactions
Liver synthesizes most of these clotting proteins
Clotting factors interact in a sequence, or cascade
Product of first reaction is enzyme that activates second reaction, etc.

44. The Extrinsic Pathway of Blood Clotting (11-7)
Begins outside the bloodstream in the vessel wall
Starts when damaged tissues release tissue factor
More damage = more tissue factor = faster clotting
Tissue factor combines with calcium and Factor VII
That combination forms an enzyme that can activate Factor X

45. The Intrinsic Pathway of Blood Clotting (11-7)
Begins in the bloodstream
Starts with activation of proenzymes exposed to collagen fibers at injury site
Proceeds with help from platelet factor released from aggregating platelets
Several reactions occur, forming an enzyme that can activate Factor X

46. The Common Pathway of Blood Clotting (11-7)
Begins when enzymes from either extrinsic or intrinsic pathway activate Factor X
Factor X activates prothrombin activator
Which converts prothrombin into thrombin
Which converts fibrinogen into fibrin
And stimulates tissue factor and platelet factors
Positive feedback loop accelerates clot formation and rapidly prevents blood loss

47. Figure 11-10 The Structure of a Blood Clot.
Platelets
Trapped
RBC
Fibrin
network
Blood clot containing trapped RBCs
SEM × 1850

48. Clot Retraction and Removal (11-7)
Fibrin network traps platelets and RBCs
Platelets contract, pulling torn edges of vessel closer together in process called clot retraction
During repair of tissue, clot dissolves through fibrinolysis
Plasminogen is activated by thrombin and tissue plasminogen activator (t-PA)
Plasminogen produces plasmin, which digests fibrin strands, breaking down clot