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The Objective
TO give information about:- Blood Types of blood The function of blood Hemopoiesis ErythropoesisBlood is a bright to dark red ,viscous , slightly alkaline ,pH 7.4.The total volume of blood in the healthy adult human is about 5 liters. blood is a specialized type of connective tissue that is made up of two parts
1- Blood cells 2- plasma ,the liquid (extracellular matrix) in which the formed elements are suspended . the formed elements of the blood are:Erythrocytes (Red Blood Cells) ,Leukocytes (White Blood Cells), and Platelets (Thrombocytes).
Human blood smear:a – erythrocytes; b – neutrophil;c – eosinophil; d – lymphocyte.
Blood cells are formed in the bone marrow. All blood cells arise from the same bone marrow stem cells. Stem cells are:- 1-immortal 2-undifferentiated. 3-pluripotent. These immortal, undifferentiated, pluripotent stem cells give rise to erythrocytes, leukocytes and platelets.The function of blood
1-Transport gases, nutrients, waste production , hormones , antibodies , chemical ions. 2- Defends against harmful microorganism , cells and viruses. 3- Prevent blood loss through coagulation (clotting). 4-Helps regulate body temperature and pH .
Hemopoiesis
Blood cells have a limited lifespan , and as a result , they are continuously replaced in the body by a process called Hemopoiesis , in this process all blood cells are derived from stem cell in red bone marrow,Erythropoesis
The regulation and production of RBCs is called erythropoesis. The mechanism of erythropoesis occurs in the following way. The kidney monitors the level of oxygen in the blood. If oxygen levels are low then the kidney secretes a hormone called erythropoetin.Erythropoetin enters the blood stream and travels throughout the body. All cells are exposed to erythropoetin, but only red bone marrow cells, which have erythropoetin receptors, respond to the hormone. Erythropoetin stimulates the production of erythrocytes in the bone marrow. These erythrocytes leave the bone marrow and move into the blood stream.
Plasma
It is the straw –colored liquid part of blood , it is about (90 %) water. A group of proteins (albumin , fibrinogen and alfa , beta ,and gamma globuline) comprise another (7 %) of the plasma .
The remaining (3 %) of plasma is composed of electrolytes , enzymes , hormones , metabolic wastes , and traces of many inorganic and organic molecules . .
Erythrocytes
Erythrocytes, also known as red blood cells (RBCs), they function to transport oxygen in the blood. The shape of erythrocytes is ideal for this function. Seen from the top, erythrocytes appear to be circular, but a side view shows that they are actually biconcaved discs. This shape increases the surface area-to-volume ratio of the cell, thus increasing the efficiency of diffusion of oxygen and carbon dioxide into and out of the cell.A
Erythrocytes
LeukocytesUnlike red cells, leukocytes have a nucleus. It is easily visible under the microscope, but only after having stained the smear. Leukocytes, or white cells, are responsible for the defense of the organism. The density of the leukocytes in the blood is 5000-7000 /mm3. Leukocytes are classified into two groups : .
1- Granulocytes , which have specific granules in their cytoplasm . There are three types of granulocytes Neutrophils, Eosinophils, and Basophils . 2-Agranulocytes , they do not have granules in their cytoplasm . There are two types of agranulocytes : Lymphocytes and Monocytes .
Granulocytes
1- Neutrophils They are the most numerous of the white blood cells ,comprising 60% - 70% of the total leukocytes population, with a nucleus consisting of 2-5 (usually 3) lobes linked by fine threads of chromatin. The cytoplasm of the neutrophil contains, small specific granules.Neutrophils are very active in phagocyting bacteria and are present in large amount in the pus of wounds. Neutrophils constitute a defense against invasion of microorganisms .
Neutrophils are known as microphages to distinguish them from larger phagocytic cells , (the macrophages)..
Eosinophils
The cells contain bilobed nucleus in which the two lobes are connected by thin chromatin strand . the cytoplasm is filled with large , eosinophilic granules..2-Eosinophils cells increase in number during parasitic infection and play an important role in the immune response to parasites.
3-Basophils
Basophils make up less than 1 % of blood leukocytes and are therefore difficult to locate in smear of normal blood . They are have an S-shaped nucleus , with large specific granules. These granules stain with the basic dye of the usual blood stain. The function of basophils is similar to that of Mast cell.Their granules contain histamine and heparin, release of histamine cause vascular changes lead to increased fluid leakage from blood vessels and may result in hypersensitivity response.
A granulocytes
1-Monocytes : Monocytes constitute (3-8) % of the blood leukocytes, they are the largest agranular leukocytes, the nucleus is oval, or kidney shaped , and is eccentrically placed. Monocytes can live in the blood for 2 to 3 days , after which they move into the connective tissue , where they may remain for a few months or longer .Monocytes differentiate into Macrophages and then destroy bacteria , foreign matter and dead cells
1-Monocytes :
MacrophagesLymphocytes :
Lymphocytes make up (20-25) % of white blood cells , they are round cells with large nucleus. Lymphocytes can be subdivided into three types: * B- Lymphocytes (B-cells) ** T- Lymphocytes (T-cells) *** Null cells (NK) Lymphocytes have a central role in the immunological defense of the body.B- Lymphocytes (B-cells) when stimulated by specific antigen differentiated into plasma cells and produce antibodies.