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Overview of Blood Blood is a fluid connective tissue. Its total volume is about 5 liters. It has many functions. Blood is made of two parts: blood cells and plasma.

Main Functions Transport of nutrients and oxygen to cells. Transport of wastes and carbon dioxide away from cells. Delivery of hormones and other regulatory substances to and from cells and tissues. Maintenance of homeostasis. Transport of humoral agent and cells of the immune system.

Plasma Its main component is water. Plasma proteins (albumin, globulins, fibrinogen) Other solutes

What do blood cells include? Erythrocytes neutrophils granulocytes eosinophils Leukocytes basophils agranulocytes lymphocytes monocytes Platelets

Erythrocytes(E, RBC) No nucleus, no organelles Average diameter 7.2μm Packed with protein hemoglobin(Hb). biconcave disks. Quite flexible. Function: oxygen and carbon dioxide transporting

The immature form in which erythrocytes are released into the circulation from the bone marrow. Blue net or granules , ribosomes Lower concentration of Hb Final maturation occurs within 24~48 hours. Less than 1% of circulating RBC. Reticulocytes

Leukocytes-granulocytes Possess two types of granules: specific granules and azurophilic granules. Granulocytes have nuclei with two or more lobes. Include the neutrophils, eosinophils, and basophils.

Neutrophils 60~70% of the leukocyte count 12~15 um in diameter Spherical, with a nucleus consisting of two to five lobes. Neutrophil cytoplasm is lightly eosinophilic and contains two types of granules. Specific granules: more,small,weak pink, contain bactericidal enzymes. Azurophilic granules: less The active phagocytes of bacteria and other foreign agents.

Eosinophils 1~4% of the leukocyte count 9~12 um in diameter Nuclei are bilobed. Their specific granules are distinctive, uniform in size, more, big, red. Associated with allergic reactions, parasitic infections.

Eosinophils Specific granules: major basic protein (MBP), eosinophil cationic protein(ECP), eosinophil peroxidase(EPO) and eosinophil-derived neurotoxin (EDN); ----destruct parasites. histaminase, arylsulfatase, collagenase. ----attenuate allergic reactions. Azurophilic granules: acid hydrolases.

Basophils 0~1% of the leukocyte count Nucleus is divided into irregular lobes. Specific granules are intensely basophilic and fill the cytoplasm. distributing unevenly. Participate in anaphylaxis, anticoagulation.

Leukocytes-agranulocytes Do not have specific granules, but contain azurophilic granules. The nucleus is round or indented. Includes lymphocytes and monocytes.

Lymphocytes 20~40% of the leukocyte count The spherical cell has a spherical densely stained nucleus with an indentation. The cytoplasm is scanty, pale basophilic . All related to immune reactions.

Lymphocytes According different size, they can be classified small, medium and large Lymphocytes . According different function, they can be classified B and T cells. They are indistinguishable in conventional blood smears.

Monocytes 3~10% of the leukocyte count The largest cells of the leukocytes(up to 20 μm in diameter) . The nucleus is oval, eccentrically placed. Precursors of the cells of the mononuclear phagocytotic system.

Platelets Nonnucleated, cytoplasmic fragments derived from megakaryocytes. Appearing in clumps in stained blood smears, purple-red colour Promote blood clotting and help repair gaps in the walls of blood vessels.

Hemopoiesis Hemopoiesis includes both erythropoiesis and leukopoiesis, as well as thrombopoiesis. In the adult, erythrocytes,granulocytes, monocytes, and platelets are formed in the red bone marrow; lymphocytes are also formed in the red bone marrow and in the lymphatic tissues.

Monophyletic theory Pluripotential stem cell (PPSC) differentiate into multipotential myeloid stem cell and multipotential lymphoid stem cell. Multipotential myeloid stem cell only in bone marrow and give rise to all blood cells other than lymphocytes. Multipotential lymphoid stem cell in bone marrow and in lymphoid tissues ,give rise to lymphocytes.

Bone Marrow Red bone marrow lies entirely within the spaces of bone, in the medullary cavity of young long bones and the spaces of spongy bone. Bone marrow not active in blood cell formation contains predominately adipose cells, giving it the appearance of adipose tissue.

Summary What is plasma? What do blood cells include? What is the characteristics of each kind of blood cells?