Specialized excitatory and conduction properties of cardiac muscles

Cardiac muscles form the bulk of the heart. Normal cardiac muscle cells of the atria and ventricles are contractile. In addition to contractile property, normal cardiac muscle cells also conduct electrical signals to neighboring cardiac muscle cells through gap junctions. Therefore, a typical cardiac muscle cell serves two basic functions: Contraction Conduction of electrical impulses […]

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The cardiovascular system

System overview: heart, blood vessels and blood constitute the cardiovascular system The cardiovascular system comprises three principal components namely the heart, blood vessels, and blood transports materials to and from various parts of the body. Among the materials transported by the cardiovascular system are oxygen, carbon dioxide, nutrients (products of digestion) and hormones. The heart […]

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Type-II hypersensitivity reactions

The hallmark of type-II hypersensitivity reaction is the antibody-mediated destruction of cells. One of the commonest type-II reactions occur during blood transfusion reactions. During blood transfusion reactions, host antibodies react with foreign antigens expressed by incompatible transfused blood cells and cause the destruction of these cells.  IgM and IgG antibody subtypes bind to cell surface […]

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Understanding type-1 hypersensitivity reactions II

Primary (preformed) mediators produce relatively short-lived biological effects Mast cells degranulation results in inflammatory reaction. Preformed mediators are mediators mast cells and basophils synthesize and store at all times. In other words, preformed mediators are always present in cytoplasmic granules of mast cells and basophils. Upon allergen stimulation, the first set of chemical mediators mast […]

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Understanding type-1 hypersensitivity reaction

Introduction The ability of our immune system to respond to, and attack potential harmful foreign agents is very important. Perhaps, even more important is the ability to recognize and attack potential harmful foreign substances while ignoring other foreign substances. Note that the emphasis here is ‘potential harmful foreign substances’ and not just any foreign substance. […]

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Inflammatory cells II

Vascular endothelial cells forms more than just a passive channel for blood Before now, scientists believed that vascular endothelium acts only as a passive barrier between blood and tissues and plays no active role in inflammation. However, current knowledge reveals that vascular endothelium and vascular endothelial cells synthesize and release a number of biologically active […]

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Inflammatory cells I

Perhaps not only white blood cells participate in inflammation, but, other cells of the body such as tissue mast cells, tissue macrophages, and vascular endothelial cells equally play crucial roles in the inflammatory process. The four most important inflammatory cells are neutrophils, lymphocytes, macrophages and vascular endothelial cells. Neutrophils, the quick response troops of inflammation […]

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Chronic inflammation

Chronic inflammation Some microbial infections can result in chronic inflammation, most especially infections with organisms such as metazoan parasites, fungi and mycobacteria. Moreover, autoimmune diseases, transplantation, and allergy can induce chronic inflammation. Generally, chronic inflammation occurs if acute inflammation fails to resolve on its own. Acute inflammation will fail to resolve if the inciting stimulus […]

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