1. Cardiovascular System
Blood

2. Composition of Blood Blood is the body’s only fluid tissue
It is composed of liquid plasma and formed elements
Formed elements include:
Erythrocytes, or red blood cells (RBCs)
Leukocytes, or white blood cells (WBCs)
Platelets (Thrombocytes)
Hematocrit – the percentage of RBCs out of the total blood volume

3. Composition of Blood
Figure 18.1

4. Physical Characteristics and Volume
Blood is a viscous, opaque fluid with a metallic taste.
Color varies from scarlet (oxygen-rich) to dark red (oxygen-poor)
The pH of blood is 7.35–7.45
Temperature is 38C, slightly higher than “normal” body temperature
Average volume of blood is 5–6 L for males, and 4–5 L for females

5. Functions of Blood
Transports gases, nutrients, hormones, and metabolic wastes
Regulates pH and electrolyte balance
Hemostasis: maintains blood volume
Defends the body against toxins and pathogens
Stabilizes body temperature

6. Blood Plasma Plasma makes up 55% of the total blood volume:
92% of plasma is water
Proteins
Albumins: maintain osmotic pressure of blood
Globulins: antibodies and transport proteins
Fibrinogens: involved in blood clotting
Nonprotein nitrogenous substances – lactic acid, urea, creatinine
Organic nutrients – glucose, carbohydrates, amino acids
Electrolytes – sodium, potassium, calcium, chloride, bicarbonate
Respiratory gases – oxygen and carbon dioxide

7. Erythrocytes (RBCs) Biconcave discs Lack a nucleus
Filled with hemoglobin (Hb), a protein that functions in transporting Oxygen and Carbon Dioxide
Normally produced in the red marrow of bones.

8. Erythrocyte Function
Erythrocytes are dedicated to respiratory gas transport
Hemoglobin reversibly binds with oxygen and carbon dioxide
Hemoglobin is composed of:
The protein globin, made up of two alpha and two beta chains, each bound to a heme group.
Each heme group carries an atom of iron, which can bind to oxygen.
As oxygen levels decrease, hemoglobin molecules release oxygen and the globin portion binds to carbon dioxide.
Each hemoglobin molecule can transport four molecules of oxygen

9. Erythrocyte Function

10. Hormonal Control of Erythropoiesis
Erythropoietin (EPO) release by the kidneys is triggered by:
Hypoxia (low oxygen) due to decreased RBCs
Decreased oxygen availability (high altitude)
Increased tissue demand for oxygen (exercise)
Enhanced erythropoiesis increases the:
RBC count in circulating blood
Oxygen carrying ability of the blood increases

11. Hormonal Control of Erythropoiesis
Figure 18.6

12. Leukocytes (WBCs)
Leukocytes, the only blood components that are complete cells:
Are less numerous than RBCs
Make up 1% of the total blood volume (normal count per cubic mm.)
Can leave capillaries through tissue spaces via diapedesis
Leukocytosis – WBC count over 11,000 per cubic mm.
Normal response to bacterial or viral invasion

13. Leukocytes (WBCs) Two categories: Granulocytes:
Neutrophils: Phagocytic, release cytotoxic chemicals
Eosinophils: attack antibody-labeled and
parasitic pathogens
Basophils: release histamines, enhance inflammation
Agranulocytes
Lymphocytes: provides specific immune response
Monocytes: macrophages engulf pathogens or debris

14. Platelets Cell fragments
Functions in the clotting mechanism (Hemostasis)
Forms a temporary “Platelet Plug” that helps seal breaks in blood vessels.

15. White blood cells
Platelets
Red blood cells

16. Neutrophil
Lymphocyte

17. Monocyte

18. Eosinophil
Lymphocyte

19. Neutrophil
Basophil
Monocyte

20. 6 3 4 2 5 1

21. 6. Neutrophil
3. Eosinophil
4. Neutrophil
2. Lymphocyte
5. Basophil
1. Monocyte

22. Sickle cell anemia: abnormal formation of hemoglobin, which causes RBC’s to be deformed, and causes poor oxygen circulation, and blood clots.

23. Leukemia: Cancer of blood forming tissues, causing elevated levels of and abnormal formation of WBC’s.

24. Hemostasis A series of reactions designed for stoppage of bleeding
During hemostasis, three phases occur in rapid sequence
Vascular Phase
Platelet Phase
Coagulation (blood clotting) Phase

25. Hemostasis

26. Hemostasis Vascular Phase:
Smooth muscles in the walls of blood vessels constrict
The decrease in the diameter of the blood vessel slows and sometimes stops blood loss.
Endothelial cells at an injury site become sticky, and cells may stick together further blocking the injury site.

27. Hemostasis Platelet Phase:
Platelets attach to “sticky” endothelial cells at the injury site.
As more platelets arrive, a “Platelet Plug” forms, a mass of cells that may block the break in the vessel wall.

28. Hemostasis Coagulation Phase: Coagulation = Blood Clotting
Occurs when a series of steps results in the formation of fibrin.
Fibrin is an insoluble protein “net” that traps blood cells and platelets which form a blood clot.
The blood clot seals off the damaged portion of the blood vessel.

29. Blood Typing
A system of categorizing blood based on the surface antigens of RBC’s (agglutinogens)
Three of the most important antigens: A, B and Rh
When serum containing anti-A or anti-B agglutinins is added to blood, agglutination will occur between the agglutinin and the corresponding agglutinogens
Positive reactions indicate agglutination (clumping) and incompatible blood type.