lab 12 circulatory

• The circulatory system consists of the blood, blood vessels, and the heart
• Blood is primarily a transport medium for substances to and from body tissues
• Blood travels within five main types of vessels: arteries, arterioles, capillaries, venules, and veins
• The pumping action of the heart circulates blood to the body's cells
• The cardiovascular system refers only to the heart and blood vessels
• Blood is considered a specialized type of connective tissue
• Blood contains cells, cell fragments, ground substance (plasma), and dissolved protein fibers (fibrin strands during clot formation)
• Blood transports oxygen, carbon dioxide, nutrients, hormones, and wastes
• Circulating blood helps maintain homeostasis by regulating pH, adjusting body temperature, and maintaining osmotic pressure of cells
• Blood can clot to prevent excessive loss from the cardiovascular system and helps protect the body against disease
• Blood is a viscous substance that varies in color from bright scarlet to a dull purplish red depending on the oxygen it carries
• The average volume of blood in the body is 5-6 L in adult males and 4-5 L in adult females
• Blood has two components: formed elements (cells and cell fragments) and plasma
• Formed elements in blood include red blood cells (erythrocytes), white blood cells (leukocytes), and platelets
• Red blood cells are non-nucleated biconcave discs containing hemoglobin
• White blood cells occur in various forms, with two major groups: granulocytes and agranulocytes
• Wright's stain is the stain most commonly used to examine blood cells. This stain contains eosin,an acid dye, and methylene blue, a basic dye.
• Nuclei, granules, and other cellular structures staindifferently with these dyes, a characteristic that helps in the identification of specific types of white bloodcells.
• The most numerous cells are the red blood cells, which function in the transport of oxygen andcarbon dioxide.
• RBCs appear as small, round, non-nucleated, biconcave discs about 7 - 8 μm in diameter.
• Red blood cells have an affinity for eosin and usually stain red or pink.
• The granulocytes are white blood cells that contain visible granules of different sizes and colors.
• There are three types of granulocytes: neutrophils, eosinophils and basophils.
• Neutrophils form 60 - 70% of the leukocyte population.
• Neutrophils are phagocytic, functioning inthe destruction of pathogenic micro-organisms and other foreign matter.
• Neutrophils range in size from10-12 μm in diameter and are easily identified by the nucleus which is normally segmented into three to sixlobes.
• The neutrophil is so named because it reacts only weakly with either theacidic eosin or the basic methylene blue dyes of the Wright's stain
• Eosinophils range from 10-12 μm in diameter and compose 2 - 4% of the leukocyte population
• Eosinophils play a role in the control of local responses associated with allergic reactions. They are alsoimportant in the defense against multicellular parasites.
• reddish-orange globular granules are evident in the cytoplasm. These granules have an affinity forthe eosin in the stain; hence, the term “eosinophil”
• eosinophil's nucleus is usually segmented into two lobes
• Basophils:

  • Form 0.5 - 1% of the leukocyte population
  • Involved in allergic reactions, releasing heparin and histamine that enhance the inflammatory response
  • Range from 8-10 μm in diameter
  • Contains large, dark purple granules that obscure the S-shaped nucleus
  • Granules have an affinity for the basic methylene blue dye, hence the term "basophil"
• Agranulocytes:

  • White blood cells that lack visible cytoplasmic granules
  • Two types: lymphocytes and monocytes
• Lymphocytes:

  • Most numerous of the agranular leucocytes, forming 20 - 25% of the leukocyte population
  • Produce antibodies and other agents involved in the immune process
  • Three sizes: small lymphocytes (6-9 μm), large lymphocytes (10-14 μm)
  • Nucleus is dark blue, round or oval in shape, may be slightly indented
  • Thin rim of pale to dark blue cytoplasm may be visible
• Monocytes:

  • Largest of the white blood cells, compose 3 - 8% of the leukocyte population
  • About 12-20 μm in diameter
  • Highly phagocytic, often sprawled out on a smear with pseudopodia evident
  • Transform into macrophages after invading infected tissue sites
  • Macrophages can engulf large particles such as whole red blood cells, malarial parasites, and necrotic tissue
  • Nucleus is large, light staining, blue-violet, round, kidney-shaped, or convoluted
  • Large amount of cytoplasm present, may appear mottled due to vacuoles and lysosomes
• Platelets:

  • Number about 150,000 to 400,000 per cubic millimeter of blood
  • Disc-shaped, 2-4 μm in diameter
  • Contain many granules but no nucleus
  • Help stop blood loss from damaged vessels by forming a platelet plug
  • Help promote blood clotting
• The purpose of a differential white blood cell count is to determine the percentage of each of thefive types of leukocytes in a sample of blood.
• Leukemia refers to a group of cancerous conditions characterized by an uncontrolled proliferation of leukocytes
• Increased percentage of a particular cell type differentiates the variety of leukemia: granulocytic, lymphocytic, monocytic
• In all leukemias, the bone marrow is occupied by cancerous leukocytes so other cell types are not formed