Blood & Circulatory System

1. Blood & Circulatory System

2. I. Blood • A. Makes up approximately 8% of body weight • B. Approximately 5 L of blood in an adult • Consists of red blood cells, white blood cells, and platelets • 1. The cells and platelets make up the “formed elements” • A blood sample is about 45% formed elements • 1. Most is hematocrit (HCT) – red blood cells • When put through a centrifuge white blood cells and platelets form a layer on top of red blood cells • Remaining 55% of blood is plasma • 1. Plasma is a mixture of water, amino acids, proteins, carbohydrates, lipids, vitamins, hormones, electrolytes, and cellular waste

4. II. Red Blood Cells (Erythrocytes) • A. Hematopoeisis • Process of red blood cell production that occurs in the red bone marrow • Lack nuclei • Had them at early stages of development but lose them to make room for hemoglobin • B. The function of red blood cells is to transport gases • Shaped like a biconcave disc • - Shape increases surface area for gases to diffuse

5. 2. Hemoglobin molecules within the cell carry oxygen • Each RBC is 1/3 hemoglobin by volume • Oxyhemoglobin = hemoglobin combined with oxygen (bright red) • Deoxyhemoglobin = oxygen has been released (darker color) • Blood rich in deoxyhemoglobin may appear bluish when viewed through blood vessel walls C. Red blood cell count (RBCC) • 1. men – 4.6 to 6.2 million per cubic mm • 2. women – 4.2 to 5.4 million per cubic mm • 3. increasing RBCC increases oxygen carrying capacity D. Red blood cells are produced in red bone marrow E. Lifespan of red blood cell is about 120 days F. The release of the hormone erythropoietin controls the rate of rbc production 1. release can be triggered by oxygen deficiency

6. G. Vitamin B12 and Folic Acid are vital for RBC production • E. Iron is required for hemoglobin synthesis • 1. body obtains iron from food (in small intestine) and from decomposing worn out rbc’s • Anemia • 1. A deficiency in the # of RBC or a reduction in the amount of hemoglobin they carry • 2. Reduces oxygen carrying capacity • Person appears pale and lacks energy • Hemochromatosis • 1. Genetic disorder in which body absorbs too much iron • 2. Iron builds up in organs to a toxic level • 3. Treatment – periodic blood removal

7. Destruction of RBC • RBC’s are flexible and elastic to squeeze through blood vessels • As they age, become less flexible and become damaged • Macrophages phagocytize and destroy damaged rbc – mainly in liver and spleen • Hemoglobin is broken down • Heme – the iron containing portion, reused in more hemoglobin • Or turns into greenish pigment called biliverdin • Biliverdin stored in liver eventually converted into an orange pigment – bilirubin • Globin – a protein

8. III. White Blood Cells (leukocytes) • Function of WBC is the protect against disease • Have 5 types- differ in size, nature of cytoplasm, shape of nucleus, and staining characteristics • Granulocytes – granular cytoplams • a. Twice the size of rbc, include neutrophils, eosinophils, and basophils • b. made in red bone marrow but short lifespan (12 hrs) • Agranulocytes – cytoplasm with out granules • B. Five types of WBCs • 1. Neutrophils - First WBC to arrive at an infection site • Phagocytize bacteria, fungi, and some viruses • 54-62% of the leukocytes

9. Eosinophils - Moderate allergic reactions and defend against parasite infestation 1-3% of leukocytes • Basophils - Migrate to damaged tissues to release histamine and heparin • A. Histamine - promotes inflammation • B. Heparin - inhibits blood clotting to increase blood flow to infected tissues • C .Less than 1% of leukocytes • 4. Monocytes - Leave the blood stream and phagocytize bacteria, dead cells, and debris in other tissues • 3-9% of leukocytes • Made in the red bone marrow

11. 5. Lymphocytes - Made up of T-cells and B-cells (important in immunity) • - T-cells attack microorganisms, tumor cells and transplanted cells • - B-cells produce antibodies, which are proteins that attack foreign molecules • - made in the organs of the lmyphatic system • C. White Blood Cell Counts • 1. WBCC is normally 5,000-10,000 • 2. an increase in the WBCC could indicate an infection • 3. leukocytosis – an increased WBBC <10,000  an acute infection appendicitis • 4. leukopenia – decreased WBBC >5,000  typhoid fever, influenza, measles, mumps, chicken pox, AIDS, polio

12. A differential white blood cell count (DIFF) lists the percentages of the types of leukocytes in a blood sample • Can help indicate what kind of infection is occurring • Leukemia - cancer of white blood cells • Blood Platelets • Thrombocytes • Not complete cells • Arise form large cells (megakaryocytes) in red bone marrow • Releases parts of cytoplasm that travel through vessels in lungs • production is triggered by release of hormone thrombopoietin • Lives for about 10 days • Platelet count is between 130,000-360,000 • Close breaks in damaged blood vessels and trigger formation of clots

13. Blood Plasma • Clear, straw colored liquid portion of the blood in which cells and platelets are suspended • About 92% water • Functions: transporting nutrients, gases, and vitamins; help regulate fluid and electrolyte balance; maintaining favorable pH • Plasma Proteins • The most abundant solute in plasma • 3 groups Albumins, globulins, and fibringen • Albumins • Smallest plasma proteins • Made in liver • Important for osmotic pressure in plasma – help regulate movement of water between blood and tissue • This controls the blood volume and blood pressure

14. Globulins • Alpha, beta and gamma globulins • Liver makes alpha and beta – transport lipids and fat soluble vits. • Lymphatic tissue makes gamma – a type of antibody • Fibrinogen • Blood coagulation • Made in the liver • Gases and Nutrients • Most important are O2 and CO2, Plasma also has nitrogen • Also carries amino acids, simple sugars, nucleotides, and lipids from digestive sys • Plasma lipids are carried by lipoprotein – triglycerides, phosopholipds, and cholesterol • Plasma Electrolytes • Sodium, potassium, calcium, magnesium, chloride, biocarbonate, phosphate and sulfate ions • Na and Cl are the most abundant

15. Hemostasis--the stoppage of bleeding • A. Three methods to stop bleeding • Blood vessel spasm • a. Cutting a blood vessel stimulates the smooth muscles in it to contract, reducing the flow of blood • b. Effects last for about 30 minutes; by then a platelet plug has formed • Platelet Plug Formation • a. Platelets stick to the exposed ends of blood vessels • b. When they contact the broken blood vessel, spiny projections protrude from their membranes • c. They stick to each other and form a plug over the vascular break • Blood coagulation--Formation of a blood clot • a. Strands of protein called fibrin are produced to form a clot • b. Blood clot begins to retract and pulls the edges of the broken vessel closer together

16. Blood Groups and Transfusions • Antigens and Antibodies • Agglutination is the clumping of red blood cells following a transfusion • Antigens are molecules on the surface of red blood cells • Antibodies are proteins that are carried in plasma • Antibodies and antigens react and can cause the blood to clump

17. ABO Blood Groups • Blood types are determined by the presence of 2 antigens on RBC membranes • Antigen A • Antigen B • 4 Blood Types: • 1. Type A - has only antigen A • 2. Type B - has only antigen B • 3. Type AB - has both antigens • 4. Type O - has neither antigen

18. Transfusions • Recipient Preferred Donor Permissible Donor • (in an emergency) • A A A, O • B B B, O • AB AB AB, A, B, O • O O O • Type O Blood --> Universal Donors • Type AB Blood --> Universal Recipients