Blood – Part 1

1. Blood – Part 1 Chapter 10

2. Blood • Is the “river of life” that surges within us. • transports everything that must be carried in the body : nutrients, wastes,& body heat • through blood vessels. • Is the only fluid tissue.

3. Composition of Blood • Blood contains both solid and liquid components. • Formed Elements – Cellular portion of blood. • Contains living blood cells. • Plasma – The fluid portion of the blood. • Nonliving fluid matrix.

4. Composition of Blood • If blood is spun in a centrifuge, 3 layers are formed: • Bottom Layer- The heavier formed elements are packed down by centrifugal force. • Most of the reddish mass at the bottom is erythrocytes (RBC that function in O2 transport).

5. Composition of Blood 2. Top Layer - The lighter plasma rises to the top.

6. Composition of Blood 3. Buffy Coat - Thin, whitish layer between the formed elements layer and the plasma layer. • Contains: • Leukocytes-WBC that act in various ways to protect the body • Platelets-cell fragments that function in blood clotting.

7. Percent Composition of Blood • Percent of the total volume of blood: 1. Erythrocytes = 45% • Percentage known as hematocrit 2. WBC & Platelets = >1% 3. Plasma = 55%

8. Physical Characteristics of Blood 1.Texture: Sticky opaque fluid; Heavier than water & about 5 times thicker (viscous) than water 2.Taste: Metallic & salty 3.Color: Varies from scarlet (oxygen-rich) to dull red (oxygen-poor)

9. Physical Characteristics of Blood • pH: Slightly alkaline (pH between 7.35 and 7.45) • Temperature – Always slightly higher than body temperature (100.4°F) • Body Weight and Volume: Accounts for approximately 8% of body weight; Volume in healthy males is about 5-6 L

10. Plasma • The liquid part of the blood. • Is ~90% water. • Over 100 different substances are dissolved in this straw-colored fluid. • Examples include: nutrients, salts, respiratory gases, hormones, plasma proteins, and various wastes • Functions: • Transports various substances around the body. • Helps to distribute body heat evenly throughout the body.

11. Plasma Proteins • The most abundant solutes in plasma. • Serve a variety of functions: • Albumin – Contributes to the osmotic pressure of blood, which acts to keep water in the bloodstream. • Clotting Proteins help stop blood loss when a blood vessel is injured. • Antibodies help protect the body from pathogens. • Plasma proteins are NOT taken up by the cells to be used as food fuels or metabolic nutrients.

12. Composition of Plasma • varies continuously as cells remove or add substances to the blood. • kept relatively constant by various homeostatic mechanisms. • When blood proteins drop to undesirable levels - liveris stimulated to make more proteins. • When the blood starts to become too acidic or too basic- the respiratory system and the kidneys are called into action to restore it

13. Formed Elements • Make up about 45% of whole blood. • Contains erythrocytes or red blood cells (RBCs). • Function: To ferry O2 to all of the cells of the body. • Contain no organelles. • Are sacs of hemoglobin (Hb). • Hemoglobin- An iron-containing protein that transports the bulk of the oxygen that is carried by the blood.

14. Shape of Erythrocytes BICONCAVE DISCS • Flattened with depressed centers. • They look like doughnuts when viewed through a microscope. • small size & peculiar shape=a large surface area relative to their volume, making them ideally suited for gas exchange.

15. Number of Erythrocytes (RBCs) • RBCs outnumber WBCs by about 1000 to 1. • Are the major factor contributing to blood viscosity. • RBCs increase, blood viscosity increases. • RBCs decrease, the blood thins and flows more rapidly.

16. Hemoglobin • The more hemoglobin molecules the RBCs contain, the more O2 they will be able to carry. • Each hemoglobin molecule can bind 4 molecules of O2

17. Hemoglobin (Hb) • The most accurate way of measuring the oxygen-carrying capacity of the blood is to determine how much Hb it contains. • A single RBC contains ~250 million Hb molecules. • Each Hb molecule can bind 4 molecules of O2. Therefore, each of these tiny RBCs can carry about 1 billion O2 molecules! • The Hb content is slightly higher in men than women.

18. Anemia • A decrease in the oxygen-carrying ability of the blood. • May be the result of: • Lower-than-normal number of RBCs • Abnormal or deficient hemoglobin content in the RBCs

19. Sickle Cell Anemia • Genetic defect that leads to abnormal Hb, which becomes sharp and sickle-shaped under conditions of increased O2 use by the body. • The deformed (crescent-shaped) RBCs rupture easily and dam up in small blood vessels. • These events interfere with oxygen delivery and cause severe pain.

20. Sickle Cell Anemia • Occurs mostly in African Americans, who live in the malaria belt of Africa and among their descendants. • Individuals with the sickle-cell gene have a better chance of surviving where malaria is prevalent. • The same gene that causes sickle cell anemia, also makes RBCs infected by the malaria-causing parasite stick to the capillary walls and then lose potassium (an essential nutrient for the survival of the parasite). • The malaria causing parasite is prevented from multiplying.

21. Polycythemia • An excessive or abnormal increase in the number of erythrocytes. • May result from: • Bone marrow cancer • Normal physiological response to living at high altitudes, where the air is thinner and less oxygen is available. • Major problem that results from high numbers of RBCs is increased blood viscosity. • Increased blood viscosity causes RBCs to flow sluggishly in the body and impairs circulation.

22. Leukocytes • White blood cells (WBCs); crucial to the bodies defense against disease. • Far less numerous than RBCs • Account for >1% of total blood volume. • Form a protective, moveable army that helps defend the body against damage by bacteria, viruses, parasites, and tumor cells.

23. WBCs: Special Characteristics • Are able to slip into and out of the blood vessels – a process called diapedesis. • The circulatory system is their means of transportation to areas of the body where their services are needed for inflammatory or immune responses.

24. WBCs: Special Characteristics • Can locate areas of tissue damage and infection in the body by responding to certain chemicals that diffuse from the damaged cells. • Called positive chemotaxis.

25. Positive Chemotaxis • Once they have “caught the scent,” the WBCs move through the tissue spaces by ameboid movement . • Ameboid Movement - Flowing cytoplasmic extensions that help them move. • By following the diffusion gradient, they pinpoint the areas of damage and rally round in large numbers to destroy foreign substances or dead cells.

26. Positive Chemotaxis AmeboidMovement - Flowing cytoplasmic extensions that help them move. • By following the diffusion gradient, they pinpoint the areas of damage and rally round in large numbers to destroy foreign substances or dead cells.

27. Number of WBCs • Whenever WBCs mobilize for action, the body speeds up their production. • twice the normal number may appear in the blood within a few hours.

28. Number of WBC’s • Leukocytosis – A total WBC count above 11,000 cells/mm3 • indicates that a bacterial or viral infection is stewing in the body.

29. Number of WBC’s • Leukopenia– Abnormally low WBC count. • Commonly caused by certain drugs, such as corticosteroids and anticancer agents.

30. Leukemia • “White blood”; Bone marrow becomes cancerous; Excessive production of abnormal WBCs. • The “newborn” WBCs are immature and incapable of carrying out their normal protective functions. • the body becomes easy prey of disease-causing bacteria and viruses.