BLOOD

Cards (55)

    • Blood transports everything that must be carried from one place to another, such as:
    • Nutrients
    • Wastes
    • Hormones
    • Body heat
  • The blood is composed of plasma (55%) and formed elements (45%). The formed elements are made up of red blood cells (RBC), white blood cells (WBC), and platelets.
  • Physical Characteristics of the blood:
    • Sticky, opaque fluid
    • Heavier and thicker than water
    • Color range
    • xygen-rich blood is scarlet red
    • Oxygen-poor blood is dull red or purple
    • Metallic, salty taste
    • Blood pH is slightly alkaline, between 7.35 and 7.45
    • Blood temperature is slightly higher than body temperature, at 38ºC or 100.4ºF
    • Blood volume
    • About 5–6 liters, or about 6 quarts, of blood are found in a healthy adult
    • Blood makes up 8 percent of body weight
  • Components of blood includes the following: A. Plasma B. Formed Elements b.1 Red Blood Cells b.2 White blood cells b.3 Platelet
  • Plasma
    • 90 percent water
    • Straw-colored fluid
    • Includes many dissolved substances:
    • Nutrients
    • Salts (electrolytes)
    • Respiratory gases
    • Hormones
    • Plasma proteins
    • Waste products
  • Plasma proteins: - Most abundant solutes in plasma - Most are made by the liver
  • (Plasma Proteins) Albumin — an important blood buffer and contributes to osmotic
  • (Plasma Proteins) Clotting proteins—help to stem blood loss when a blood vessel is injured
  • (Plasma Proteins) Antibodies — help protect the body from pathogens
  • Erythrocytes (Red Blood Cells or RBCs) - Main function is to carry oxygen
    • RBCs differ from other blood cells
    • Anucleate (no nucleus)
    • Contain few organelles; lack mitochondria
    • Essentially bags of hemoglobin (Hb)
    • Shaped like biconcave discs
  • Normal count is 5 million RBCs per cubic millimeter (mm3 ) of blood
    • Hemoglobin is an iron-bearing protein
    • Binds oxygen
    • Each hemoglobin molecule can bind 4 oxygen molecules
    • Each erythrocyte has 250 million hemoglobin molecules
    • Normal blood contains 12–18 g of hemoglobin per 100 milliliters (ml) of blood
  • Homeostatic imbalance of RBC
    - Anemia is a decrease in the oxygen-carrying ability of the blood due to:
    • Lower-than-normal number of RBCs
    • Abnormal or deficient hemoglobin content in the RBCs
    • Sickle cell anemia (SCA) results from abnormally shaped hemoglobin
  • Polycythemia
    • Disorder resulting from excessive or abnormal increase of RBCs due to:
    • Bone marrow cancer (polycythemia vera)
    • Life at higher altitudes (secondary polycythemia)
  • Increase in RBCs slows blood flow and increases blood viscosity
  • Leukocytes (White Blood Cells or WBCs) - Crucial in body’s defense against disease - Complete cells, with nucleus and organelles - Able to move into and out of blood vessels (diapedesis) - Respond to chemicals released by damaged tissues (known as positive chemotaxis) - Move by amoeboid motion - 4,800 to 10,800 WBCs per mm3 of blood
  • (Clinical Correlation)
    Leukocytosis - WBC count above 11,000 cells per mm3 of blood - Generally indicates an infection
  • Leukopenia - Abnormally low WBC count - Commonly caused by certain drugs, such as corticosteroids and anticancer agents
    Leukemia - Bone marrow becomes cancerous - Numerous immature WBC are produced
  • (Types of leukocytes) Granulocytes - Granules in their cytoplasm can be stained - Possess lobed nuclei - Include neutrophils, eosinophils, and basophils
  • (Types of Leukocytes)
    Agranulocytes - Lack visible cytoplasmic granules - Nuclei are spherical, oval, or kidney-shaped - Include lymphocytes and monocytes
  • (Types pf Granulocytes)
    Neutrophils
    • Most numerous WBC
    • Multilobed nucleus
    • Cytoplasm stains pink and contains fine granules
    • Function as phagocytes at active sites of infection
    • Numbers increase during infection
    • 3,000–7,000 neutrophils per mm3 of blood (40–70% of WBCs)
  • (Types of Granulocytes)
    Eosnophils
    • Nucleus stains blue-red
    • Brick-red cytoplasmic granules
    • Function is to kill parasitic worms and play a role in allergy attacks
    • 100–400 eosinophils per mm3 of blood (1–4 percent of WBCs)
  • (Types pf Granulocytes)
    Basophils - Rarest of the WBCs - Large histamine-containing granules that stain dark blue - Contain heparin (anticoagulant) - 20–50 basophils per mm3 of blood (0–1 percent of WBCs)
  • (Types of Agranulocytes) Lymphocytes - Large, dark purple nucleus - Slightly larger than RBCs - Reside in lymphatic tissues - Play a role in immune response - 1,500–3,000 lymphocytes per mm3 of blood (20–45% of WBCs)
  • (Types of Agranulocytes)
    Monocytes
    • Largest of the white blood cells
    • Distinctive U- or kidney-shaped nucleus
    • Function as macrophages when they migrate into tissues
    • Important in fighting chronic infection
    • 100–700 monocytes per mm3 of blood (4–8 percent of WBCs)
  • Platelets
    • Fragments of megakaryocytes (multinucleate cells)
    • Needed for the clotting process
    • Normal platelet count is 300,000 platelets per mm3 of blood
  • Hematopoiesis is the process of blood cell formation
    • Occurs in red bone marrow (myeloid tissue)
    • All blood cells are derived from a common stem cell (hemocytoblast)
  • Hemocytoblasts form two types of descendants
    • Lymphoid stem cell, which produces lymphocytes
    • Myeloid stem cell, which can produce all other formed elements
  • Since RBCs are anucleate, they are unable to divide, grow, or synthesize proteins
    • RBCs wear out in 100 to 120 days
    • When worn out, RBCs are eliminated by phagocytes in the spleen or liver
    • Lost cells are replaced by division of hemocytoblasts in the red bone marrow
  • Formation of Red Blood Cells
    • Rate of RBC production is controlled by a hormone called erythropoietin
    • Kidneys produce most erythropoietin as a response to reduced oxygen levels in the blood
    • Homeostasis is maintained by negative feedback from blood oxygen levels
  • Formation of White Blood Cells and Platelets
    • WBC and platelet production is controlled by hormones
    • Colony stimulating factors (CSFs) and interleukins prompt bone marrow to generate leukocytes
    • Thrombopoietin stimulates production of platelets from megakaryocytes
  • Hemostasis is the process of stopping the bleeding that results from a break in a blood vessel
    • Blood usually clots within 3 to 6 minutes
    • The clot remains as endothelium regenerates
    • The clot is broken down after tissue repair
  • Hemostasis involves three phases
    • Vascular spasms
    • Platelet plug formation
    • Coagulation (blood clotting)
  • Step 1: Vascular Spasms
    • Immediate response to blood vessel injury
    • Vasoconstriction causes blood vessel to spasm
    • Spasms narrow the blood vessel, decreasing blood loss
  • Step 2: Platelet Plug Formation
    • Collagen fibers are exposed by a break in a blood vessel
    • Platelets become “sticky” and cling to fibers
    • Anchored platelets release chemicals to attract more platelets
    • Platelets pile up to form a platelet plug (white thrombus)
  • Step 3: Coagulation
    • Injured tissues release tissue factor (TF)
    • PF3 (a phospholipid) interacts with TF, blood protein clotting factors, and calcium ions to trigger a clotting cascade
    • Prothrombin activator converts prothrombin to thrombin (an enzyme)
    • Thrombin joins fibrinogen proteins into hairlike molecules of insoluble fibrin
    • Fibrin forms a meshwork (the basis for a clot)
    • Within the hour, serum is squeezed from the clot as it retracts
    • Serum is plasma minus clotting proteins
  • (Disorders of Hemostasis) (7.4.2 Undesirable Clotting) 7.4.2.1 Thrombus
    • A clot in an unbroken blood vessel
    • Can be deadly in areas such as the lungs
  • (7.4.1 Disorders of Hemostasis) (7.4.2 Undesirable Clotting)
    Embolus
    • A thrombus that breaks away and floats freely in the bloodstream
    • Can later clog vessels in critical areas such as the brain