By A. Umul. Philadelphia Biblical University.
This leads to formation of conjugated bilirubin comprising both mono-and diglucuronides which have high water solubility zyloprim 300 mg without a prescription. Each of these cell types is quite distinct in appearance and each has a specific biological function discount 100 mg zyloprim mastercard. Despite the extreme structural differences among the cells of the blood, strong evidence exists that all of the blood cells are the progeny of a single type of cell: the hemapoietic stem cell (or pluripotent hematopoietic stem cell or hemocytoblast). The process in the production of all the various cells of the blood from the hematopoitic stem cells is called hematopoiesis. Hematopoiesis begins early during embryogenesis, and the process undergoes many changes through fetal and neonatal development. Unlike organ systems that are formed in early life and continuously replaced, the hematopoietic systems undergo turnover and replenishment throughout life. Early embryogenesis: Yolk sac Early fetal life: Liver and spleen Late fetal life- bone marrow After birth: Before adolescence- the bone marrow of all the bones After adolescence - the bone marrow of only the spine, ribs, pelvis, and upper parts of humerus and femur Formation of different blood cells from stem cells Figure 35 shows the successive divisions of the hematopoietic stem cells from which all the cells in the circulating blood are derived. The larger portion of the reproduced stem cells, however, differentiates to form other cells. The different committed hematopoietic cells, when grown in culture, will produce colonies of specific types. This is helpful in predicting the Rh type of a fetus carried by an Rh-negative mother, and in paternity testing. Rh antigens are presumed to be proteins and are important in providing the stability of the red cells membrane. Because D antigen is the strongest antigen (immunogen) of red cell antigen, this may occur in up to 70% of such persons. Sensitization may also occur in an Rh-negative mother carrying an Rh-positive fetus, most commonly at the time of birth, when fetal cells escape into the maternal circulation. Fortunately these antibodies do not fix complement and the red cell destruction is mild and extra vascular. Kell, Duffy, and Kidd Blood Group Systems Antigens in these systems may each lead to the development of immune antibodies after an antigen-negative individual is exposed through transfusion or pregnancy. Compatibility Testing Because most patients have naturally occurring antibodies, and some develop immune antibodies in other blood group systems that are clinically significant, the choice of red cells for transfusion is to be done carefully to avoid life-threatening hemolytic transfusion reactions. If any other antibodies have been found, the donor’s red cells must be negative for the corresponding antigens. Finally, two drops of the donor’s cells must be mixed with the patient’s serum at room 0 temperature, at 37 C, and after the additions of the Coombs reagent. Factors from plasma can be concentrated Whole Blood Platelets and plasma are separated from the red cells shortly after donation, and plasma may be further fractionated. Such preservatives include citrate, which binds with calcium, and phosphate, dextrose, and adenine, to improve red cell survival. Packed Red Cells: Most anemic should be transfused with packed red cells, after removing 80% of the plasma, so that the volume of the component is about 150 ml. Washed Red Cells Such preparations are needed for individuals who are IgA deficient and have had a life- threatening reaction to plasma containing IgA. The washed red cells must be used within 24 hours to avoid growth of contaminating bacteria. Membrane and metabolic changes occur to 0 0 the red cells during this storage 1 - 6 C. Freezing requires the addition of glycerol, a cryoprotectant that enters the cells and limits the formation of intracellular crystals. Platelets 0 Platelets are concentrated by centrifugation and stored at 20-24 C since refrigeration destroys their ability to aggregate. Granulocytes must be transfused as soon as collected, since it is not possible to preserve their function by storage at any temperature. Granulocyte transfusions are frequently accompanied by fever and respiratory symptoms in the recipient; these reactions can often be fatal. Immunity means the body’s ability to resist or eliminate harmful foreign materials or abnormal cells. The leukocytes and their derivatives defend against invasion by disease-causing microorganisms by phagocytizing the invaders or causing their destruction by more complex means; identify and destroy cancer cells that arise within the body phagocytize cellular debris resulting from dead or injured cells; it is essential for wound healing and tissue repair. They can be rapidly transferred from their site of production or storage to where ever they are needed There are five different types of leukocytes Leukocytes vary in number, function, and structure. Five different cells - neutrophils, eosinophils, basophiles, monocytes and lymphocytes - each have different characteristic morphology and function. Neutrophils, eosionphils, and basophiles are classed as polymorphonuclear granulocytes. They are classified on the basis of varying affinity of their granules to the red dye eosin and basic dye methylene blue. Monocytes and lymphocytes are mononuclear agranulocytes Leukocytes are produced at varying rates depending on the changing needs for defense of the body All leukocytes originate from the same undifferentiated pluripotential stem cells in the red bone marrow that also produce erythrocytes and platelets The bone marrow produces all circulating blood cells except lymphocytes, which are produced by lymphocyte colonies in lymphoid tissues. The myeloblast is the earliest recognizable precursor in the granulocyte series that is present in the red bone marrow. A series of four to five divisions are associated and the mature neutrophil, cytoplasmic granules develop.
The histology of transverse tissue from long bone shows a typical arrangement of osteocytes in concentric circles around a central canal buy 100 mg zyloprim free shipping. Cancellous bone looks like a sponge under the microscope and contains empty spaces between trabeculae order 300 mg zyloprim with visa, or arches of bone proper. The formed elements circulating in blood are all derived from hematopoietic stem cells located in bone marrow (Figure 4. Leukocytes, white blood cells, are responsible for defending against potentially harmful microorganisms or molecules. Some white blood cells have the ability to cross the endothelial layer that lines blood vessels and enter adjacent tissues. Lymphatic capillaries are extremely permeable, allowing larger molecules and excess fluid from interstitial spaces to enter the lymphatic vessels. Lymph drains into blood vessels, delivering molecules to the blood that could not otherwise directly enter the bloodstream. In this way, specialized lymphatic capillaries transport absorbed fats away from the intestine and deliver these molecules to the blood. When attached between two movable objects, in other words, bones, contractions of the muscles cause the bones to move. Other movements are involuntary, meaning they are not under conscious control, such as the contraction of your pupil in bright light. Muscle tissue is classified into three types according to structure and function: skeletal, cardiac, and smooth (Table 4. Comparison of Structure and Properties of Muscle Tissue Types Tissue Histology Function Location Long cylindrical fiber, Attached to bones and striated, many Voluntary movement, produces heat, protects around entrance points Skeletal peripherally located organs to body (e. Skeletal muscles generate heat as a byproduct of their contraction and thus participate in thermal homeostasis. Shivering is an involuntary contraction of skeletal muscles in response to perceived lower than normal body temperature. Under the light microscope, muscle cells appear striated with many nuclei squeezed along the membranes. The striation is due to the regular alternation of the contractile proteins actin and myosin, along with the structural proteins that couple the contractile proteins to connective tissues. The cells are multinucleated as a result of the fusion of the many myoblasts that fuse to form each long muscle fiber. Unlike skeletal muscle fibers, cardiomyocytes are single cells typically with a single centrally located nucleus. A principal characteristic of cardiomyocytes is that they contract on their own intrinsic rhythms without any external stimulation. Attached cells form long, branching cardiac muscle fibers that are, essentially, a mechanical and electrochemical syncytium allowing the cells to synchronize their actions. The attachment junctions hold adjacent cells together across the dynamic pressures changes of the cardiac cycle. It forms the contractile component of the digestive, urinary, and reproductive systems as well as the airways and arteries. Neurons propagate information via electrochemical impulses, called action potentials, which are biochemically linked to the release of chemical signals. Neurons display distinctive morphology, well suited to their role as conducting cells, with three main parts. A long “tail,” the axon, extends from the neuron body and can be wrapped in an insulating layer known as myelin, which is formed by accessory cells. The synapse is the gap between nerve cells, or between a nerve cell and its target, for example, a muscle or a gland, across which the impulse is transmitted by chemical compounds known as neurotransmitters. Bipolar neurons possess a single dendrite and axon with the cell body, while unipolar neurons have only a single process extending out from the cell body, which divides into a functional dendrite and into a functional axon. When a neuron is sufficiently stimulated, it generates an action potential that propagates down the axon towards the synapse. If enough neurotransmitters are released at the synapse to stimulate the next neuron or target, a response is generated. The second class of neural cells comprises the neuroglia or glial cells, which have been characterized as having a simple support role. Recent research is shedding light on the more complex role of neuroglia in the function of the brain and nervous system. The astrocytes have many functions, including regulation of ion concentration in the intercellular space, uptake and/or breakdown of some neurotransmitters, and formation of the blood-brain barrier, the membrane that separates the circulatory system from the brain. Microglia protect the nervous system against infection but are not nervous tissue because they are related to macrophages. Oligodendrocyte cells produce myelin in the central nervous system (brain and spinal cord) while the Schwann cell produces myelin in the peripheral nervous system (Figure 4. In the latter case, understanding the impact of aging can help in the search for ways to diminish its effects. Whether biological, chemical, physical, or radiation burns, all injuries lead to the same sequence of physiological events. Inflammation limits the extent of injury, partially or fully eliminates the cause of injury, and initiates repair and regeneration of damaged tissue.
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