Chapter 11: The Cardiovascular System--Blood

1. Chapter 11: The Cardiovascular System--Blood

2. The functions of blood • Transportation: of dissolved gases, nutrients, hormones, and metabolic wastes. • Regulation: of pH, blood clotting, body temperature and renal control. • Protection: against harmful toxins and pathogens

3. Properties & Composition of Blood • Blood volume: On average, 5-6 L in men and 4-5 L in women • Properties: • Temperature: 38°C (100.4°F) • Viscosity: high (5x more than water) • pH: 7.35-7.45 (slightly alkaline, basic) • Composition: • 55% Plasma: matrix of blood that carries formed elements, gases, nutrients and wastes throughout the body. • 92% Water • 8% Electrolytes, Proteins & Nutrients • 45% Formed Elements • Red Blood Cells • White Blood Cells • Platelets

4. Plasma proteins • Albumins (60%): of plasma proteins, produced in the liver, maintain osmotic balance (via water retention) • Globulins (35%): • Immunoglobulins: attack foreign proteins and pathogens; antibodies • Transport (escort) Proteins: carry compounds that are not water soluble (i.e. lipids) • Fibrinogens: function in blood clotting when converted to fibrin. *Liver synthesizes many of these proteins.

5. Give blood! Save lives!

6. Formed elements • Composition: (Hematocrit) • 99.9 % Red Blood Cells (Erythrocytes) • <.1% White Blood Cells (Leukocytes) • ~ 1 to every 1000 RBCs • <.1% Platelets • Hemopoiesis (hematopoiesis): process of blood cell production • Formed from embryonic blood cells during 3rd week of development • Formed in the liver and spleen during 2-5th month of development • Formed in red bone marrow during adulthood

7. Red blood cells (Erythrocytes) • Shape: Biconcave discs • Mature RBCs lack nuclei and other organs (Erythropoiesis) • Life cycle: ~120 days; 1% replaced each day (3 million new cells each second!) • Hemoglobin: made of two globular proteins; contains heme pigment which holds an iron ion that binds with oxygen

8. Clinical note: Sickle Cell ANemia • Cause: genetic mutation that affects the globular protein of hemoglobin • Sickled cells can easily clot and cause oxygen starvation of tissues

9. Blood typing (Fig. 11-7) • Four Blood Types: • Type A: surface antigen A, plasma Anti-B Antibodies • Type B: surface antigen B, plasma Anti-A Antibodies • Type AB: surface antigen A & B, no anti-A or B antibodies • Type O: no surface antigens A or B, plasma Anti-A & Anti-B Antibodies • (+/-): Determined by presence or absence of Rh antigens on RBCs • Cross-reactions: mixing of blood types can cause agglutination (clumping) of RBCs and eventual hemolysis (RBC destruction) • Anti-Rh antibodies are not normally present in plasma, unless exposure sensitizes an individual.

10. Clinical note: HDN • Hemolytic Disease of the Newborn • Cause: mother and child’s blood type differs and plasma antibodies from the mother cross the placenta and attack fetal RBCs • Usually occurs due to sensitization during delivery of previous child, which affects next pregnancy.

11. White blood cells (leukocytes) • Larger than RBCs, have nuclei, lack hemoglobin • Function: defense against pathogens, toxins, wastes and abnormal/damaged cells • Two groups: granulocytes & agranulocytes • Amoeboid movement • Migration out of the blood stream • Some capable of phagocytosis

12. White blood cells (leukocytes)Fig. 11-8 & Table 11-3 • Granulocytes • Neutrophils • Eosinophils • Basophils • Agranulocytes • Monocytes • Lymphocytes

13. neutrophils • 70% differential count • Active phagocytes (esp. bacteria) • Death recruits other WBCs and forms pus • Produced in bone marrow

14. Eosinophils • 2-4% differential count • Two-lobed and dyed red by eosin • Attack anti-body labeled materials by exocytosis (secretion) of toxins • Produced in bone marrow

15. Basophils • <1% differential count • Deep purple/blue with many granules • Migrate to injury sites and stimulates inflammation and prevents blood clotting (heparin & histamine) • Produced in bone marrow

16. Monocytes • 2-8% differential count • Large free or fixed macrophages • Aggressive phagocytes • Produced in bone marrow

17. Lymphocytes • 20-30% differential count • Large nucleus with “halo” of cytoplasm • Integrates with lymphatic system • Do not rely on phagocytosis • Produced in bone marrow and lymphoid tissues

18. Platelets (thrombocytes) • Cell fragments that function in blood clotting • Formed from megakaryocytes • “Stick” together at injury sites to stop bleeding (hematosis)

19. hemostasis • Hemo “blood” + stasis “halt”: stops bleeding • Vascular Phase: constriction of damaged blood vessels (~30mins); blood vessel spasm • Platelet Phase: “sticky” platelets form a platelet plug • Coagulation Phase: conversion of fibrinogen to fibrin

20. Clinical note: abnormal hemostasis • Excessive coaguluation • Thrombus: blood clot attached to wall • Embolus: moving blood clot • i.e. strokes, pulmonary embolism • Inadequate coagulation • Hemophilia • Missing clotting factor • No cure, X-linked therefore affects more males • Symptoms including excessive bleeding (external and internal)